IN THE COUNTY COURT OF VICTORIA
AT Melbourne
COMMON LAW DIVISION	Revised
Not Restricted
Suitable for Publication	
General List
Case No. CI-19-03074

ANGELA FRANCES LIVINGSTONE	Plaintiff	
		
v		
		
CITY OF MELBOURNE	Defendant	

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JUDGE:	HIS HONOUR JUDGE LAURITSEN 	
WHERE HELD:	Melbourne	
DATE OF HEARING:	18-20, 23 and 24 March; 25 and 26 May 2020	
DATE OF JUDGMENT:	11 November 2020	
CASE MAY BE CITED AS:	Livingstone v City of Melbourne	
MEDIUM NEUTRAL CITATION:	[2020] VCC 1775		

REASONS FOR JUDGMENT
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Subject:		
Catchwords: 		
Legislation Cited:	Wrongs Act 1958	
Cases Cited:	March v E & MH Stramare (1991) 99 ALR 423; Henville v Walker [2001] HCA 52; Roads and Traffic Authority v Royal (2008) 82 ALJR 870; Michos v Council of the City of Botany Bay [2012] NSWSC 625; Proprietors Strata Plan 14198 v Cowell (1989) 24 NSWLR 478; Marshall v Berndt [2011] VCC 384; Robson v Leischke (2008) 72 NSWLR 98; City of Richmond v Scantelbury [1991] 2 VR 38; Holloway v Newcastle City Council [2013] NSWDC 62; Jones v Dunkel (1959) 101 CLR 259; Stockwell v State of Victoria [2001] VSC 497; State of Queensland v Baker [2018] QCA 168; Banco de Portugal v Waterloo & Sons Ltd [1932] AC 452
Judgment:		

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APPEARANCES:
	Counsel	Solicitors	
For the Plaintiff	M Lapirow	Abbott & Mourly	
			
For the Defendant	M Latham	Hunt & Hunt Lawyers	

HIS HONOUR:

Introduction 
1	In 1997, Angela Livingstone bought 50 Dryburgh Street, West Melbourne. The house on this property was a small, single storey Victorian building. Since this dispute concerns it, I will call it the “original building”. In 2006, Dr Livingstone built a two storey extension at the rear of the property. In 2009, the City of Melbourne planted on the footpath outside 50 Dryburgh Street a white cedar tree or, more technically, melia azedarch. It was planted about 3 metres from the western or front wall of the original building.  
2	During 2006, very minor cracks appeared in the rear walls of the original building. They remained very minor by the time of the planting of the tree. During 2011 and 2012, the cracking increased and the footpath adjacent to the tree began to heave. In that period, Dr Livingstone told the defendant of both the cracking and the heaving. On 28 February 2014, the defendant replaced a section of the damaged footpath adjacent to the tree.
3	Before April 2015, Dr Livingstone found she could not open or close her front door properly. The cause is ascribed to the differential movement in the house’s foundations. The cracking and other damage worsened. 
4	On 17 April 2015, Dr Livingstone wrote to the defendant about the damage and the need for rectification. On 15 September 2015, the defendant installed a concrete barrier in the footpath outside Ms Livingstone’s house. Since then, the tree has grown. Also since then, there has been considerable internal cracking in the original building. Ultimately, Dr Livingstone issued this proceeding. 
5	Dr Livingstone pleads two causes of action, in nuisance and negligence. She sought the removal of the tree, a permanent injunction preventing the planting of any other tree and damages, both for incurred and predicted expenses. As pleaded, they amount to $453,530.83, with the largest item being the proposed demolition of the original building and its rebuild. 
6	Primarily, the defendant denies the tree is the cause of the cracking and other damage to Dr Livingstone’s house. Apart from denying the claim in negligence, it pleads contributory negligence. 
7	The defendant sought to rely on s24AI of the Wrongs Act 1958. It sought, unsuccessfully, to join Citywide Service Solutions Pty Ltd as a defendant. In view of s24AI(3), I cannot have regard to the comparative responsibility of any person who is not a party to the proceeding.   
Circumstances    
8	Dryburgh Street runs north to south. The original building at 50 Dryburgh Street is a single storey building built in about 1886. It faces west to the street. On its northern side is a laneway. The laneway is not flat, it falls toward the street and slightly to the south as the land slopes from north to south. The stormwater downpipes of the properties bordering the laneway empty into it. In its centre is a channel, graded so that water runs into it. The channel conveys rainwater, including stormwater, towards the street.  On the other side of the laneway is another property, apparently containing a factory. 
9	As originally built, the house was small, comprising two rooms, kitchen, laundry and a hallway with a corrugated iron roof. It had solid brick walls resting on bluestone footings laid on brick rubble and on top of natural clay. It shares a party wall with 48 Dryburgh Street, to its south. There is no nature strip for 50 Dryburgh Street or, indeed, for the three other houses to its south. Instead, there is a footpath, starting at the edge of the property and ending at the gutter.    
10	Dr Livingstone bought the property in 1997 with her former husband. The kind of distress which became apparent much later was not evident. In 2000, she and her then husband separated and, later, his interest in the property was transferred to her. Although Dr Livingstone has remarried, she remains the sole proprietor of the property.    
11	At the time of its purchase, the house was in good condition. Although there were no problems with the roof (for example, leaking), Dr Livingstone did not like the way it looked. She had the roof replaced at the “front” of the house. The “front” encompasses a veranda, two rooms and a passageway. Behind the “front” was a kitchen, laundry and bathroom. These rooms were covered by a skillion roof.  
12	During 2004 and 2005, Dr Livingstone planned a major renovation due to the need for extra living space. Initially, she considered erecting a second floor to the original building. Her architect obtained a report from Hardrock Geotechnical Pty Ltd (the Hardrock report) and advised against it. The second storey option was discarded and instead a two-storey building was built at the rear of the existing building. Dr Livingstone and her family left the home and lived elsewhere during these renovations. These works were completed by March 2006 when her family moved back into the house. Apart from the new building, some works were done on the existing building: repainting of the front and replastering of minor cracking on the rear or eastern wall. There was no problem with the internal western wall.  
13	After the extension was built, Dr Livingstone saw very minor cracking at the rear of the original house. However, between 2006 and 2009, the state of the original part of the house remained the same:
“Between the period when you came back into the house in 2006 and 2009, were there any issues with the house, any cracking, any issue of its building or its stability? – There were certainly um,-- no, no, I don’t recall any issues at all.” 
14	The parties relied on photographs or images contained in certain websites. Photographs taken in November 2009 do not show cracking in the western external wall, rather cracking in the paintwork. 
15	Dr Livingstone denied the suggestion she neglected the house:
“—I made – oh, any time there was a problem, I looked into it. For instance, when there were termites known to be in the area, I had the house inspected for termites. It was clear.”  
16	Pausing there. The front of the house is depicted in many photographs exhibited for this proceeding. Looking from the street to the front of the house, one notices there is no nature strip. Instead, there is a wide footpath. The tree was planted in the footpath in an area near to the kerb and gutter. The house has an open metal fence and behind it is a tiled veranda. At the northern wall of the veranda, very near the fence is a downpipe. Its outlet faces the street. It is not linked to a stormwater drain. It empties rain water onto the veranda and towards the street. The veranda has a slight slope towards the street. Water leaving this downpipe passes over the veranda towards the footpath and the gutter. 
17	Beside the northern wall of the house is a cobblestone laneway, separating No 50 from No 52. Along the laneway, 50 Dryburgh has an alcove where bins are kept.  
The tree 
18	In 2009, the defendant planted the tree. It is a white cedar. This type of tree was planted in front of other properties in the street including the four semi-detached houses of which 50 Dryburgh Street is one. When planted, the tree was about Dr Livingstone’s shoulder height. Dr Livingstone is of medium height for a woman. The tree was supported by three wooden stakes and cable ties. At the time, Dr Livingstone liked the fact of the tree. It was green and pretty and would provide shade when it was hot.
19	The tree outside number 50 grew much faster than the trees planted outside 48, 46 and 44 Dryburgh Street. The tree is now about 9 metres high. On average, at maturity, it reaches 12 metres. The tree is higher, bigger and looks healthier than the other three trees in the row.  
Complaints 
20	During 2013 and, possibly, in 2012, Dr Livingstone rang the defendant on four or five occasions to complain about the tree and its effect on her house. She spoke to different people on these occasions. One conversation she remembers well because of the response:
“Q: … And was there any direction or advice given to you? – Yes. Um, he said that if the damage was as bad as I said, then the council may need to inspect the property and put a works order or demolition order on it.”
21	Later, she added:
“A: I can remember the circumstances. I was outside on my mobile phone kind of pacing up and down near the tree and saying I’m really worried about this and that was when he said if the damage was as bad as that then Council, that if I kept drawing it to their attention Council would have to put a works order or a demolition order on the home.”  
22	Since she could not then afford repairs, Dr Livingstone hoped the defendant might remove the tree or “do something about it or fix matters”.
23	When she contacted the defendant, the only evidence Dr Livingstone possessed of the link between the tree and damage to her house was the evidence of her eyes:
“Q: And you had no evidence to support that? – I had the timeline from when the tree was planted and watching it grow and watching the distress to my house proportionate with that.”
24	On 17 April 2015, Dr Livingstone wrote to the defendant. Relevantly, it reads:
“I am making a claim for repairs to 48 and 50 Dryburgh St, West Melbourne, as a result of root damage causing subsidence of the foundations and severe cracking in both houses. The external doors were all but impossible to open or close, the internal doors did not fit and the cracks were widening by the day. 
The onset of these problems was in February of this year and the acuity of the situation was such that we had to have emergency repairs done to both properties, sharing the costs with our neighbours Bruno and Anne Moras. The other two houses in the row are also affected but not as severely. 
Three years ago trees were planted in front of our houses. No root barrier was installed, and when more recently works were done on the footpath outside 48 and 50 Dryburgh St, the soil was not compacted afterwards before the asphalt was replaced. 
As both houses were in danger of having ceilings fall in, we were able to organise urgent foundation work by Uretek today for these two houses. 
We are requesting reimbursement of the costs associated with this, and that you inspect and organise a similar process for the other houses in the row. We are also requesting either a root barrier or removal of the trees and replacement with less damaging varieties, although this would be a less optimal outcome …”  
25	When Dr Livingstone said the problem started in February, she was referring to the sticking of the doors. It was this issue which prompted the letter.  
26	On 27 April, the defendant replied, rejecting her claim. There was further correspondence during the rest of 2015, 2016 and into 2018. Finally, in March 2018, she instructed solicitors to institute proceedings because:
“… I felt I’d done everything I reasonably could and I’d been knocked back every time I’d tried to do anything. I couldn’t see how just talking to the same people and getting the same knockbacks was going to help anyone.”
27	Shortly before engaging solicitors, she gave the defendant an engineers’ report from Roscon Property Services but it, too, was rejected.  
Root barrier
28	Meanwhile, on 15 September 2015, the defendant installed a root barrier. It was placed in the footpath. Constructed from concrete, it is 1.5 metres deep and runs in front of each of the four houses. The inner edge of the barrier is about 75 centimetres from the front edge of 50 Dryburgh Street and about a metre from the tree. One purpose of the barrier was to sever the tree roots and causing those on the house side of the barrier to die. On the house side of the barrier was a thick plastic sheet, which acts as a vapour barrier. It is meant to minimise the passing of moisture through the barrier. If working correctly, the soil on one side of the barrier will be drier than the soil on the other, but not below the barrier.    
29	Since the installation of the barrier, suckers from the tree have reappeared. They disappeared after the barrier was installed but have reappeared.  
Underpinning 
30	There have been two episodes of underpinning, in 2015 and 2019. 2015 was the first time Dr Livingstone took steps to fix the cracking problem. She had asked the defendant for help and was under the impression that it might assist. Dr Livingstone did not act until about April 2015, explaining why in this passage:
“Q: And there was no good reason for you delaying 3 years to take any steps to address the issues with the cracking and foundation of the property? – I don’t think that’s accurate. I did keep hoping, rather foolishly, that Council might take out the tree. Um, that things might in fact not progress to the stage that they have.”  
31	In 2012 and 2013, her position was complicated. Dr Livingstone’s husband was not then working and she had two small children. She was working part-time, three days a week, and earning about $180,000 per year before taxation. Dr Livingstone is a psychiatrist. 
32	In April 2015, Uretek Ground Engineering (Uretek) performed a form of underpinning. This consisted of injecting resin or a similar substance into the footings to lift them. Uretek worked along the front or western wall. It appears the process did not address the cause of the damage. Dr Livingstone paid Uretek a total of $3,218.41, being her share of the cost. 
33	In March 2018, Dr Livingstone took photographs showing a crack above the front door as seen from the hallway. The crack was so wide it allowed sunlight between 3.00pm and 4.00pm in the afternoon. It horrified her. Another photograph, taken during the next month, showed further deterioration:
“Q: Did you notice any change? – Um, yes. 
Q: In what way? – I noticed that things were continuing to just, um, get worse. The rubble was accumulating. We had to sweep the floors pretty much every day because there was so much rubble dropping there, and the cracks were steadily becoming more obvious.”        
34	In June 2018, Dr Livingstone decided to put items from the first room of the original house into storage. She used that room as her library. The items included books, CDs, DVDs, shelves, a couch and a large cupboard. She was worried about falling rubble and the roof falling in. She rented a storage unit. From the second room, she removed a double-sized cupboard, its contents, table and chairs. These goods remain in storage up to today. She continues to pay storage fees, now at $326 per month.     
35	In 2019, Dr Livingstone engaged Fred Heinemann Co Pty Ltd (Heinemann) to perform underpinning work. It was paid $31,950. Metro Building Surveying confirmed the underpinning was done according to engineering standards. She received a certificate of compliance. Mr Eracleous, a structural engineer, described the work:
“… there’s eight underpins that have been performed at the northern wall on the western side, western path and there’s five of them and there’s three of them under the western wall, three underpins.”
36	After these works, Heineman filled in most of the internal cracks and some of the external ones. For example, it did not fill a large crack between the roof and the party wall.  
37	Very shortly before the trial started, Dr Livingstone’s husband took up part of the floor of the original building and took a series of photographs underneath the floor.
Expenses     
38	Over several years, Dr Livingstone has paid for services to investigate and repair the damage to her house: 
(a)	Uretek: $6,561.50. This is the overall cost, her share was half.
(b)	MJW Constructions: $1,860.00;
(c)	Heinemann: $20,000 on 23 June 2019 and $11,950.00 on 24 June 2019 – a total of $31,950.00;
(d)	Vision Filter: $1,000. This business packed and moved the contents of two rooms to storage;
(e)	National Storage: for storage of the contents at monthly rates varying between $290.00 and $331.00. It is currently $326 per month.
Photographs 
39	Over several years, Dr Livingstone and her husband took a number of photographs of the original building. It is appropriate to examine them now. Exhibit C comprises photographs on pages 428 to 461 of Dr Livingstone’s Court Book. 
February 2015
40	The photographs at pages 428 and 429 show sections of the front of the house in 2015. At page 429, the photograph shows the front doors of 48 and 50 Dryburgh Street and the party wall. That photograph does not show any external damage to 50 Dryburgh Street. 
February 2017
41	The photograph at page 430 was taken in February 2017 and shows a sizeable crack under the external front window. 
March 2018
42	At page 431, the photograph depicts the decorative iron work pulling away from the party wall. At pages 432 and 433, the photographs show daylight between the party wall and the veranda’s roof. 
43	At page 434, the photograph shows most of the tree and part of the front. In particular, it shows a large vertical crack above the veranda. At page 435, the photograph does not show the crack on page 434, but it does show the continuation of the crack below the veranda’s roof and beside the front door. Some of the crack is visible through the decorative iron work. 
44	At page 444, there is an internal photograph showing an enormous crack starting in the architrave of the party wall, proceeding across the western wall of the hallway and then proceeding down the join of the northern wall of the hallway. It was taken in March 2018. To Dr Livingstone, she could see the sun shining through the crack. This had become apparent a “number of weeks” before the photograph was taken and it horrified her. 
45	At page 445, the photograph is a close up of part of the crack taken in the next month. To Dr Livingstone, it depicts a worsening of the cracking seen in the previous photograph. Whether it is or not, the cracking is dreadful. So much debris fell out of these cracks that “pretty much every day” Dr Livingstone or her husband needed to sweep the floor. To stop this, they masked the cracks with tape. This is seen in the photographs on pages 446 and 447, which were taken in February 2018. 
46	The photographs at pages 448 to 451 show cracking in the walls of the south-east corner of the original house. This is at the end of the hallway. The entrance to the extension appears on the left hand side of the photographs on pages 448 to 450. At page 451 is a close up photograph of the “hole” appearing at the intersection of three cracks in the ceiling, and seen at pages 448 and 450. 
47	The photograph at page 459 is a photograph of the part of the archway in the hallway, facing west. It shows a significant, but limited, crack in the archway and a long, thin crack in its northern wall.    
April 2018
48	At page 439, the photograph shows the lock of the front door with the tongue of the lock incorrectly positioned. According to Dr Livingstone, you could neither open the door nor shut it.      
May 2018
49	At page 437, the photograph is one of the best in evidence showing the tree, the house, both original and extension, and most of the laneway. As in the photograph on page 435, it shows entry through the front gate barred by tape. At pages 437, 440 and 441, these photographs show two large cracks: one around the stained glass window above the front door; and the other where the roof meets the party wall. 
February 2019
50	At page 441, the photograph was taken in February 2019. It shows a gap between the metal roof of the veranda and the party wall. Dr Livingstone’s husband installed a vertical piece of wood, apparently to support a horizontal piece of wood underlying the metal roof. At about this time, Dr Livingstone decided underpinning was required. 
51	The photographs at pages 452 to 457 show cracking in the second room of the original building, being the last room before the extension. There are two large cracks: one from the ceiling to the door frame to the hall; and the other from the door frame to the ceiling. The photograph at page 458 depicts rubble lying on the dado in the south-east corner of the hallway. It was common then to find debris on it. 
52	Photographs 460 and 461 are taken of the hallway but looking east. They are taken from the opposite direction to the photograph on page 459. They show the other side of the archway with a crack. Both photographs show rudimentary patching of cracks. 
March 2019
53	At page 438, the photograph shows the enormity of the crack depicted at page 435. To me, the crack is enormous. 
Development of cracking
54	The photography is idiosyncratic. It does not attempt to be a forensic examination of the development of the damage in the house. To an extent, it does achieve that purpose. The photographs of 2015 and 2017 focus on the external front of the house and the damage. Only in 2018 are there photographs looking at the interior. In those photographs, the cracking is shocking with photographs showing attempts to plaster over cracks. In 2018 and 2019, there are photographs of the second bedroom and the hallway opposite it.
55	In 2018 and 2019, these photographs reveal major damage to the front of the house, both inside and outside, in and about the archway in the hall and in the second bedroom and the adjacent hallway.                   
Other photographs
56	There are a number of other photographs. These were taken by the expert witnesses. Some show the damage to the original house. Some are worth noting now. 
57	Mr Kirkwood, a licensed plumber, inspected the house on 24 April 2018. He took 41 photographs. They are in colour and of reasonable quality. 
58	Photograph numbered 10 shows a large crack above and beside the front door. Photograph 11 shows a thick horizontal crack in what seems to be a pillar at north-western corner of the original building. Photographs 15 to 19 show cracking inside the house.     
Hardrock report 
59	On 17 February 2005, a geotechnical engineer, Trevor Ackland, of Hardrock Geotechnical Pty Ltd, inspected the house and reported to Dr Livingstone. Mr Ackland examined the foundations because Dr Livingstone was considering building a second storey above the original building. Two boreholes were drilled. 
60	Mr Ackland noted “some fine diagonal cracking” on the rear northern corner of the house and minor rotation of the north wall. He drew a location plan, depicting the existing residence, the position of three boreholes and the rest of the property. At what was the eastern wall of the second room or, as Mr Ackland describes it, “the rear north eastern corner”, he marked the position of what he calls a “fine crack”. Near to this crack is borehole 1. 
61	According to AS2870-1996, Mr Ackland classified the site as Class P due to the depth of the filling intersected in borehole 1. He described the strip footings as brick, the founding depth of 900 millimetres, and the founding material as natural silty clay. These underlying clay soils were highly reactive and in Class H:
“Based on experience in the area, the founding zone soils are highly reactive and shallow foundations are known to perform relatively poorly. This is confirmed by the diagonal cracking and minor rotation of the northern wall of the residence. The potential for further foundations movements is relatively high and the existing foundation movement is expected to continue.”  
62	In the context of a proposed first floor extension, he described the footings as inadequately stiff to withstand the potential differential foundation movements, being bricks only at a shallow depth. Although the footings had sufficient capacity to support a light weight first floor, he could not guarantee their performance “due to the high potential for reactivity based foundation movement due to moisture variations”. He thought some abnormal moisture conditions were occurring based on the performance of the residence and recommended measures to keep the founding soils at a constant moisture and limit volumetric changes. Interestingly, he added:
“Any trees within close proximity to the existing residence be removed. It is usual to prohibit trees within a distance equal to 1 times the mature height of the tree for class H site classification. There generally has to be a compromise between the presence of trees and cracks. It should be noted that tree roots are attracted to moist ground conditions. If a relatively low and constant ground moisture condition can be maintained in the vicinity of the foundations, tree roots, which may cause shrinkage in later dry periods, will be attracted to other areas.”   
63	For each of the boreholes, Mr Ackland noted the moisture of the core at various depths. In all bar one, the moisture content is described as “moist”. In borehole 1, the fill was described as both “moist” and “wet”. There was 0.85 metre of fill and 0.1 metre of silty clay. The borehole stopped at 0.95 metre. The fill is described as “silty CLAY/clayey SILT, gravel, roots”. Boreholes 2 and 3 were drilled to 1.5 metres respectively.  
Roscon 
64	Mehran Orangi is a structural engineer with Roscon Property Services. At the request of Dr Livingstone, he inspected the property on 8 January 2018.
65	Mr Orangi saw cracks to the exterior and interior of the original house. To the exterior and the front facade, most of the cracks closed after underpinning by Uretek. He noticed cracks in adjacent properties which were in the root zone of their respective trees. Apparently, he re-attended the property on 28 February 2018 and took photographs. To him, these showed further movement.    
66	There were an enormous number of cracks in the interior areas of the original building with widths up to 7 millimetres. He considered ground movement had affected all areas of the building including the entrance, hallway, front and middle bedrooms. Some of the cracks had opened up or moved due to the change in the amount of moisture in the soil following the Uretek work, which he described as underpinning. He noted masking tape covered cracks in different parts. 
67	He photographed the tree. Its distance from the front façade of the building was less than 3 metres. To him, the laneway was covered by impermeable bluestone. He saw no structural damage to the outside of the north wall. He noted Uretek’s work was to the front of the building. He noted 48 Dryburgh Street had suffered similar structural damage.
68	Based on his experience of 25 years in the building area, Mr Orangi considered the building movement at the front of the original house was caused by the trees on the “road reserve”. Tree roots cause foundation soil movement in two ways: growth in cross-section exerts upward pressure on the footings; or roots in the vicinity of the footings absorb much of the moisture in the foundation soil, causing shrinkage or subsidence. He recommended obtaining the advice of an arborist on the “specification of trees in the vicinity” and on the appropriate tree root barrier. He considered the existing tree root barrier was inadequate in that it did not prevent roots encroaching onto the property. He also recommended a soil test to confirm that the soil is clay.    
69	As to reinstatement, on the basis that the problem caused by the roots is rectified and after waiting 6 to 12 months to allow the moisture content to stabilise, he recommended engaging a registered builder specialising in the reinstatement of buildings, the filling of cracks with flexible sealant to allow minor movements in cracks and the fixing, sanding and painting of all damaged areas.  
Rodriguez
70	On 11 November 2019, Alejandro Rodriguez of Structural Melbourne inspected the property. He did so at the request of Roscon Property Services to determine whether the tree was the cause of the damage to the house. Mr Rodriguez is a structural and geotechnical engineer. 
71	Mr Rodriguez was given three documents including the Smolders’ report. He drilled his own borehole “adjacent to the existing footing” to find a segment of the tree root and determine the soil profile. He found tree roots. He tested the soil profile to a depth of 1.8 metres. He even took a sample of leaf from the tree to compare with the tree root. 
72	Mr Rodriguez did not give oral evidence and only two pages of his report were admitted into evidence. The second page is a black and white photograph of an excavation. It carries the caption “Tree root as found under the footing of the house”. In the absence of an explanation of what the photograph shows, the content of the two pages is of no probative value. I do not know where exactly the borehole or excavation is, where the roots are coming from, or whether they are alive or dead. 
Eracleous 
73	Elias Eracleous is a forensic structural engineer. He visited the property on four or five occasions and wrote three reports. The first is a preliminary report, the second is a supplement to the first having received a geotechnical report, and the third is the “expert” report, with litigation in mind. His view is primarily that the tree has caused the damage. 
First report 
74	In 2018, Dr Livingstone engaged FMG Engineering (FMG) to investigate the damage to the original building. FMG sent Mr Eracleous, a senior forensic structural engineer, to investigate. On 6 July, he conducted a non-intrusive inspection of the property in the presence of Dr Livingstone’s husband and reported.
75	Mr Eracleous saw cracking when he inspected the original building. It was largely to the southern end in the hallway. There were some cracks to the northern wall in the front bedroom and perpendicular to the western wall. The bedroom had a crack which was consistent with settlement towards the west. There was cracking in the second bedroom with the furthest crack from the street in the south-east corner of the second bedroom. This was consistent with outward rotation of the building towards the north.      
76	Mr Eracleous made what he termed six pertinent findings: 
(a)	there was extensive cracking to the fabric of the building throughout the original building with the nature of the cracking consistent with the damage caused by differential movements of the foundations or footings; 
(b)	the degree of the cracks varied from the minor (widths from hairline to 3 millimetres) to moderate/severe (widths up to 25 millimetres); 
(c)	a floor and brick course level survey indicated a general pattern of relative footing settlement towards the north and north-west regions; 
(d)	the propagation of the cracks was consistent with the conclusion drawn from the survey in (c) above, namely the direction and location of foundation and footing movement; 
(e)	the soil was expected to be highly reactive clay (Class H1/H2), which undergoes notable changes in volume with the variation of moisture content; 
(f)	there is a “maturing” tree, about 7.5 metres high and about 2.5 metres from the front veranda and believed to have been planted in about 2009.   
77	Mr Eracleous considered the damage to the original building was due to differential footing movement which, in turn, was due to on-going variations in the moisture content of the highly reactive foundation soils. Those variations were due to one or more of several factors: 
(a)	normal soil moisture conditions associated with normal seasonal climatic changes; 
(b)	abnormal soil moisture conditions caused by the tree-root drying/suction effects of the tree, which was well within its theoretical “zone of influence”. He considered this factor to be a “significant contributing factor”; 
(c) the general nature of a house of this age which is inherently more susceptible to differential foundation/footing movements. 
78	Mr Eracleous concluded the tree-root drying/suction effects from the tree was a significant contributing factor to the damage. He drew support from Google street-view photographs indicating the external cracking to the western wall and north-west corner was not apparent before 2009 and its gradual and progressive development was consistent with the growth of the tree.  
79	Mr Eracleous recommended a geotechnical investigation and testing.  
Smolders Geotechnical 
80	Smolders Geotechnical Pty Ltd (Smolders) was engaged to investigate and classify the site according to AS2870-2011. Xavier Smolders, an engineering geologist, attended the property on 17 October 2018.   
81	Using AS2870-2011, he classified the site as CLASS P. He drilled two boreholes at sites nominated by Mr Eracleous. Borehole 1 was drilled in the alcove or bin area and borehole 2 on the front veranda or porch near the north-west corner of the house. Appendix 1 is a diagram showing their positions. 
82	Samples were taken at 500 millimetres intervals except in BH2 where basalt was encountered at 1,800 millimetres. The last sample was taken at that depth. Eight samples were analysed for moisture content and soil suction and the results appear on page 8 of the report. For example, at 2 metres in BH1, the soil suction figure in picofarads is 3.4. At 1.8 metres in BH2, the corresponding figure is 4.05. For BH2, the moisture content varied between 28.10 per cent to 30.5 per cent. While for BH1, the variation was between 30.90 per cent to 49.60 per cent. 
83	On page 12 of the report, there is a hand drawn plan of the site together with the laneway and part of 52 Dryburgh Street. It is not to scale. It shows the positions of the boreholes, the position and height of the tree (about 7.5 metres), and a tree (about 8 metres) in the rear yard of 52 Dryburgh Street, together seven bushes described as “extensive Wisteria creeper”. 
84	Appendix 111 of the report sets out the soil profile of each borehole at 100 millimetres intervals. Interestingly, both boreholes encountered “rootlets”: in BH1 at 800 millimetres; and in BH2 at 1,000 millimetres.   
Second report
85	On 5 December 2018, Mr Eracleous wrote a supplementary report. Following his recommendation in his first report, FMG engaged Smolders to conduct an investigation, which it did, In his report, Mr Eracleous summarised its findings: 
(a)	in its current condition, according to AS2870-2011, the site is classified as CLASS P (problem site). This classification is due to abnormal soil moisture conditions caused by adverse factors including the presence of the tree; the depth of fill material in the upper soil profile; and the development of the property; 
(b)	the characteristic surface movement ranges between 41millimetres and 60 millimetres (+ or – 5 millimetres). It is a highly reactive site (Class H1/H2) when subject to normal soil moisture conditions; 
(c)	the characteristic surface movement potentially caused by tree’s drying/suction effects is 37millimetres (+ or – 5 millimetres). The combination of this with the movement in (b) yields an extremely reactive site (Class E); 
(d)	the two boreholes revealed an upper topsoil consisting of silt, gravel and sand, varying between 200 millimetres to 600 millimetres in depth. Underneath is natural silty clay and clay; 
(e) borehole 1 (BH1) was located in the alcove and borehole 2 (BH2) in the front veranda area. BH1 was a reference borehole because it was remote from the tree drying/suction effects; 
(f) the moisture content of soil samples from BH2 was notably drier than the corresponding soil samples from BH1. The moisture difference is an indicator of the tree root drying/suction effects; 
(g) the maximum soil suction at BH2 at 2 metres below ground is 4.05 picofarads (pF). At the same depth for BH1 the reading is 3.4pF. Since pF is a logarithmic scale, the difference is a factor of about 4.5. The soil suction (the soil’s affinity for moisture) at BH2 is 4.5 times greater than at BH1 at that depth. 
86	Commenting on (g), Mr Eracleous said: 
“This confirms the advice contained in [his] Report 1 that the subject tree is causing exacerbated suction levels within the reactive foundation zone soils. The degree/magnitude of the exacerbated tree root suction is up to approx. 4.5 x greater than regions which are beyond the subject tree’s theoretical zone of influence with regard drying/suction effects. This is occurring in-spite of the reported installation of a tree root barrier, the specific details of which (i.e. type, nature, extent, location, timing, etc) are currently unknown.”
87	He reaffirmed his earlier advice about the causes of the damage and, in particular, the degree/magnitude of the contribution of the tree as a significant contributing factor to the observed damage to the building.   
Third report  
88	On 22 February 2019, Mr Eracleous wrote a third report. Its purpose was to set out the extent and nature of the necessary rectification work. 
89	After discussing options in section 6 of his report, Mr Eracleous concluded the full demolition and removal of the original part of the house and its reconstruction was a more practical and effective rectification option. In section 8, he set out in some detail what needed to be done to effect the demolition and rectification.     
Tree and suction
90	Mr Eracleous saw the suction effect caused by the tree as a significant contributing factor to the rotation and the observed damage to the house.  
91	How does the suction work? 
92	Trees cause suction because they are thirsty for water. The roots of trees get too near the foundations and draw moisture away. This creates a suction vacuum within the soil. The drier the soil the greater the suction. The difference in soil moisture readings is significant. In Melbourne generally, suction levels are 3.5 to 3.6 picofarads. In the alcove it is 3.4 at 2 metres while in BH2 it is 4.05 at the depth of 1.8 metres. Because it is a logarithmic scale, this 4.5 times greater or about two times greater than expected. 
93	As to soil suction and movement:
“…So the way we identify whether there’s – whether a tree is actually affecting the situation [is] to take the moisture content away. So that’s our control borehole and soil suction and moisture content and soil suction in close proximity and what we measure is the difference between the two and it’s that difference that’s what’s important, not the numbers, not the absolute numbers that we’re getting but the differential of those numbers. So, in the case of the moisture content we’re getting 30 at the front and mid to high 40s away from the tree. So it’s drier at the western side in close proximity to the tree. But more crucially in my opinion is soil suction because when we assess tree roots in the Australian Standard we don’t talk about moisture content. We talk about soil suction and that’s in appendix H of AS 2870 and what we observed with soil suction which is the actual factor we looked at and not moisture content is that we had soil suction levels four and a half times greater at the front of the house than in the courtyard area….So, the magnitude of suction at the front of the house is four and a half times greater than that of the courtyard, which means that there’s a source of suction – abnormal suction that’s been caused and that’s been caused by the tree. There’s no other site factor that could generate that suction affect.” 
94	And again:
“A: … As soon as we get a variation of suction between one region and another we’re going to get differential movement. The characteristic surface movements that are defined in the Australian Standard are related to suction, they’re not related to moisture.” 
95	The tree can still be damaging the property even if the tree roots have not passed the barrier. Its influence does not necessarily depend on the extent of its roots. The nature of the tree root system depends on the species and does not affect their suction potential or their requirement for water. The photograph at Defendant’s Court Book (“DCB”) at page 993 shows roots cracking the asphalt paving towards the house.  
96	The tree is a significant contributing factor to causing rotation. There is another factor – a lot of sunlight on the northern side and none on the south.  
97	The tree root barrier creates a barrier up to 1.5 metres but not deeper than that.  
98	The soil is clay and highly reactive. Drying causes shrinkage and wetting expansion. Anything built on top of those soils will drop or heave (rise) respectively. The original building covers the property. The only area exposed seasonal climatic effects is the bin storage area.
99	Without the tree, the amount of movement a site can expect between extreme drying and extreme wetting. The usual range is 40 to 75 millimetres. Here, it is 37 millimetres plus or minus 5 millimetres. With the tree it is 78 millimetres. In effect, it increases the reactivity of the soil and exacerbates drying and suction. It causes differential footing movements and building damage. He saw settlement of the building towards the north (laneway) and north-west (towards the tree). He determined settlement by doing a floor level survey. There were lower levels at the north and north-west area relative to the south. He saw damage to the walls inside on the southern end. The damage to the hallway walls is due to the outwards rotation of the building towards the north and north-west. 
100	The cause:
“… the nature of the movement that we’re observing is associated with drying shrinkage of the foundation clays which shrink – are known to shrink when dry. It’s not associated with wetting and swelling of clays.” 
101	And again:
“… the way the building is performed is not related to water ingress drainage issues at the subject property. It’s related to drying shrinkage of the clay soils causing settlement, not heave …” 
102	However, moisture content can cause the foundations to heave.  
103	The photograph on page 431, taken in March 2018, shows the pulling out of the anchor (spaghetti) from the drilled hole in the wall. The cause:
“The settlement of the footings along the northern and north-western region of the building which is causing an outward rotation of the entire building and pulling away from the southern party wall.”        
104	Comparing the photographs at page 437 (taken in May 2018) and page 438 (taken in March 2019) shows widening of the crack. 
105	Mr Eracleous could not say whether the tree roots would go around the barrier and into the laneway. But the drying and suction effects will go around and under the barrier.
Extension
106	Looking at the original building and the extension, they have different footing systems and differential footing movements occur between different footing systems. If there were movements, Mr Eracleous would expect damage but not the damage shown in the photographs on pages 450 and 451.
Downpipes
107	Mr Eracleous disagreed that the downpipes had the capacity to affect the foundation soils because the footings at 900 millimetres are too deep and downpipes do not deliver enough water to affect that deep. Moreover, the floor levels and crack propagation were inconsistent with localised heave in the north-east and north-west corners and there was no evidence of heave at the locations.    
108	Mr Eracleous could not see any water from the veranda downpipe getting into the foundation system. It would not go through the tiles, the concrete underneath and then into the soil. It would flow across the tiles onto the footpath and then to the gutter. 
109	In the alcove, the tiles are laid side by side without grouting. There is a gap between each tile. In a low rainfall event, 90 per cent of the rain would run to the laneway and, of the rest, a very minimal amount would pass through the tiles. In a major rainfall event, Mr Eracleous expected 50 to 100 millimetres of soil below the pavers to become wet. This would not affect the foundations. 
110	When he inspected the laneway, Mr Eracleous saw nothing to lessen its effectiveness in directing water to the street: 
“… There’s no evidence of pooling of water or any localised soft spots or depressions that would suggest that there was a problem with drainage with regard to water just ponding in certain areas and not draining away.” 
111	Mr Eracleous disagreed with the view expressed by Mr Lawrence at [49] of his first report where the latter says: 
“Considering the abnormally wet clay soil encountered adjacent to the north western corner of the building, it is also likely that at least some of the movement and distress in this area may be the result of localised heave of the highly reactive foundation clays in the area.”  
Vegetation at 52 Dryburgh Street
112	As to the vegetation in 52 Dryburgh Street, Mr Eracleous said the vine is 3 metres high and 5 metres away from 50 Dryburgh Street. It does not have deep roots. It is out of its theoretical zone of influence. The tree is 7.5 metres high and 10 to 10.5 metres away. It is also not within its zone of influence. The suction tests in the alcove were 3.4 pF, which is “very low”. This means there was no exacerbated suction. The Australian Standard refers to shrubs, not vines. If vines were a problem they would be included. The tree and the vine are possibly influencing their respective zones but not the house. 
113	Mr Eracleous and Mr Lawrence agree on one thing. As Mr Lawrence said at paragraph 44 of the first report:  
“… it is evident that the movement and distress in the subject building has been caused predominantly by drying related shrinkage settlements of the highly reactive foundation clays …”
114	They disagree on the rest of the sentence: “as a result of the drying action of surrounding trees and vegetation”.
115	The root barrier is not deep enough, for trees can cause drying and suction up to a depth of 3 metres.  
Extension 
116	The presence of a malthoid or bond breaker separates the extension from the original building. Movement in the footings of the extension cannot effect those in the original building and vice versa. 
117	Dr Livingstone’s husband photographed part of the sub-floor space of the original building. Looking at those photographs, Mr Eracleous concluded the sub-floor space was three or four bricks high and was lower than the external ground. The photographs showed no evidence of water ponding there as supposed by Mr Smith at paragraph 93 of his report. The photographs show efflorescence which is a long-term phenomenon. The distress to the building is not due to permeation of moisture over 130 years. The timbers are dry. There is no evidence of mould. Noting the loose timbers, if water was ponding, he would expect evidence of moisture damage. The reason the sub-floor space is dry is because the laneway is performing satisfactorily.  
Telstra pit
118	Mr Eracleous considered the Telstra pit was irrelevant for the purposes of foundation movement. Potentially, the pit could elevate moisture content in the immediate vicinity. Potentially, it increased the moisture observed in borehole 1 of Smolders, but it did not cause damage because this is settlement, not heave.   
Tree root barrier   
119	Mr Eracleous considered the barrier as too shallow at 1.5 metres to stop tree induced drying and suction. The extent of the tree roots is immaterial to the degree of suction. The barrier needed to go to a depth of 3 metres to affect the drying and suction.  
120	He considered 43 per cent moisture content in borehole 5 of Mr Lawrence as very moist, while the content of borehole 3 at 26.8 per cent as significantly or notably drier. However, these boreholes went to a depth of 600 millimetres, which is not the founding depth. However, boreholes 1, 3 and 4 went to the depth of 700 millimetres with samples from boreholes 5 and 6 taken at 700 millimetres and 1600 millimetres. He expected different results if the boreholes had gone deeper. He re-iterated the boreholes went to 700 millimetres and the footing system is 900 millimetres below the surface. The barrier does nothing in relation to the foundation movement.  
Hardrock report 
121	With the Hardrock report, Mr Eracleous disagreed that the rotation is consistent with the property’s present symptoms.   
122	His view is expressed in this answer in cross-examination:
“… So in 2009 you showed me those photos and that’s a 130 year old building that’s performed relatively well for its age with no visible building distress to the western wall and no indication of significant outward rotation of the southern wall, albeit it is referred to here, although it hasn’t been qualified with a photo or a measurement. Then all of a sudden from post – at some point in recent time we see, you know, post 2015 we start to see from Google street photos a significant cracking and deformation of the flashing and cracking over the door opening which indicated that something has occurred that has caused an exacerbated – a significant exacerbation that’s caused outward rotation and associated damage with the building, and in my opinion that is the tree that was planted in 2009 that has grown quite rapidly over time and the presence of the root barrier has not arrested its effects on the building.”
123	The Hardrock report identified a fine crack next to borehole 1 as the distress to the building. To Mr Eracleous, this is consistent with a slight outward rotation of the wall and is consistent for a building of this construction era and age.  
Smith 
124	As to the opinions of Mr Smith, Mr Eracleous disagreed with paragraph [112] of his report that there is heaving in the southern wall. However, he accepted there was cracking of 10 millimetres or more in that wall. He agreed the western wall has slumped towards the northern wall and the hallway arches show the northern portion of the building has slumped. He denied saying in his report that the damage is isolated to the western wall. He agreed the mortar between the bluestone pavers will shrink creating cavities at their interface but, when raining, 95 per cent of the water will drain away. In the Google photos and his inspection he never saw evidence of ponding in the laneway or curving channel. There is no underground stormwater drainage in the street. He disagreed that the foundations of the extension causes differential settlement in the original building because the two buildings are separated. Hardrock exposed one footing only and it was 900 millimetres deep. The other footings are not necessarily 900 millimetres deep. A strip footing is at the same depth because they excavate a trench and pour concrete.  Based on photographs of street views, in 2015, the zone of influence of the tree was at least 6.5 metres, taking it into the front room. He agreed underpinning in 2011 or 2012 would have reduced the effects of the tree.    
Remedy
125	When Mr Eracleous saw the building in 2018, the only practical solution was to demolish the original building and rebuild. He described the rebuild as to footings (board piers). His recommendation assumes the tree remains. One cannot demolish the party wall. But it needs continuous underpinning. It is conventional underpinning, not the injection of resin. Continual underpinning of the party wall carries the risk of lateral soil movement but the magnitude of the lateral movement is inconsequential compared with the damage to the building. It would not threaten the viability of the neighbour’s party wall. Demolition would expose the soil under the original house to the elements for the first time in 130 years. That could raise the moisture content. The exposure could be protected. Mr Eracleous explained that what causes damage is not the reactivity of the soil, but the different moisture condition in one part compared with another.    
Kirkwood
126	Russell Kirkwood is an experienced licensed plumber. On 24 April 2018, he examined the property at the request of Dr Livingstone. He saw significant cracking affecting the original building. Overall, he found no evidence that the roof plumbing or below ground drainage was responsible for any increase in ground moisture conditions.
127	There were three minor, but noteworthy, areas. One was the discharge of stormwater onto the pavers in the “gated alcove area”. He commented:
“… this would ideally be discharged out into the laneway or the paved area could be concreted to ensure no moisture is entering the soil area however we note that this area is some considerable distance from the epicentre of manifestation of movement.”   
128	The stormwater downpipes do not connect to a legal point of discharge. 
129	He did not see any pooling at the front. At the front, there was a stop tap. Water from the downpipe travels about 200 millimetres before leaving the veranda. It drops onto the footpath and grades away slightly to the north-west before entering the kerb.  
130	His photograph 31 shows the timber gates to the alcove. They are not water tight because pavers are uneven. Photograph 33 shows a downpipe which covers an area of about 20 square metres of the roof. Even in a one in a hundred year event, the amount of water from this area would be small. The other downpipe, depicted in photograph 32, deals with a smaller area, less than 15 square metres.  
131	The area of the open deck is about 11 square metres. Only a small amount of water would fall on it. No other roof water discharges into it. It feeds the alcove. It has marginal effect on the alcove and pavers. To connect these downpipes to the storm water drainage at the rear of the property would be expensive. Running an arterial pipe through the home is expensive. To connect the front downpipe to the rear stormwater would cost at least $20,000.     
132	There are four downpipes on the northern side, but one flows onto the lower roof, so there are three which flow to the ground. Connecting the front downpipe to the storm water drain at the rear of the property would cost $2,000 or $3,000. To connect the two downpipes in the alcove to the stormwater drain at the rear would cost between $10,000 and $15,000. One would run a pipe through a bulk head inside the building. If it were his home he would not do it because the house is too small. It would have been an ideal time (most cost effective) to address drainage at the time of the building of the extension, costing probably less than $5,000.  
133	For a borehole in the alcove, the driller removed a paver to drill it. It is very close to the sewer trench. The moisture content may be influenced by water seeping down into the sewer trench. The sewer trench is at least 1 metre down. The main reticulation sewer main runs in the laneway. Water will follow the trenches which contain the mains. The moisture could be coming from a long distance away via the sewer.    
134	Mr Kirkwood recommended concreting the paved areas because water can get through the grout lines. Drainage needs installing.
135	In the laneway, the cobblestones are in very good condition.  They are not sunken. There is an even gradient to the centre drain. The joints between the cobblestones appear cemented. There was no pooling of water. The kerb and gutter were in reasonable condition. The more gradient of the roadway, the less permeable: “It’s about time, with water it’s about time spent on something”.    
Michael Pavey   
136	Michael Pavey is an very experienced quantity surveyor. Dr Livingstone’s solicitors requested him to advise on the cost of rectification based on the scope of the works set out by Mr Eracleous in section 8 of his report dated 22 February 2019.  
137	Mr Pavey inspected the house on 6 March 2019 and wrote his report two days later. He estimated the cost of rectification at $346,830. He identified 11 broad areas of work and broke them into their constituent parts. He added amounts for the builders’ preliminaries and margin, consultant’s fees, a 10 per cent contingency and goods and services tax to reach that figure.   
138	The area of the original house is 4.6 square metres. His estimate of the scope of works and the cost was based on the demolition of the original building and its restoration to its condition if it were undamaged.
139	Commenting on Mr Orangi’s proposal, adopting it would not fix the problem. It would fix up the cracks with flexible pop seal or similar and paint over them. One could do that for less than $30,000.    
Andrew Smith 
140	Andrew Smith is a very experienced forensic structural engineer, construction manager and design manager. At the request of the defendant’s solicitors, he inspected the house on 6 February 2020. It was a clear day and it had not rained in the preceding 24 hours. He prepared two reports, dated 24 February and 22 March 2020. 
141	In his first report, Mr Smith summarised his findings: 
(a)	the damage is due to moisture change to the foundations. The primary cause of the damage is the water from the stormwater downpipes flowing to the foundations through porous and open surfaces;
(b)	the tree did not contribute to the damage. The tree is too small to have caused damage from 2011. 
142	Mr Smith measured the levels of the floors in the original house. Since the building had been underpinned in 2015 and 2019 and partially relevelled, he could not say that the levels pointed to heaving or settlement. 
143	He believed the north wall of the house had rotated fully along its full length. It had moved about 10 millimetres to the north. The whole building had moved 10 to 20 millimetres to the north.  The movement was uniform, not concentrated at the front of the building and was not due to the small tree. The movement of the party wall could be due to the underpinning in 2015 and 2019. He saw no significant heave in the bluestone kerb and channel due to the tree. 
144	The building showed signs of neglect, noting a rotten beam of the fascia of the veranda. 
145	He believed the downpipes discharged water which made its way to the foundations, caused heaving and the damage. The downpipe in the north west corner was the likely cause of heaving resulting in the observed damage. The disturbed soil of the Telstra pit would allow moisture to enter the subsoil and also cause heaving. 
146	He noted 50 per cent of the roof area of the original building, and 25 per cent of the roof area of the extension, spilt water onto the porous landscaping in the alcove or the bluestone paving through the downpipes. 
147	Mr Smith examined the interior of the original building. His photographs show a considerable amount of patching of the cracks in the hallway. He considered the cracking in the hall’s archway and what he describes as the south east corner is not due to a tree 13 or 15 metres distant. He also considered the south eastern portion of the building had subsided due to the extension connected to it.    
148	To his report, Mr Smith attached a 2009 Google Maps photograph of the front of the house. It depicts the tree, which I daresay is taller than Dr Livingstone’s shoulder. He attached a 2014 photograph from the same source showing a tall, but thin tree. Mr Smith estimated its diameter at 150 millimetres. 
149	Using the 2009 image, Mr Smith commented: 
“Nearmap shows that in 2009 that the tree planted was very small and it is not considered possible that 3 years after the juvenile tree were planted 3 metres from a solid brick strip footing building would have caused structural damage along the entire length (8 metres long) of the Victorian portion of the dwelling.” 
150	To Mr Smith, in the absence of underground stormwater, the Telstra pit acts as a drain and leaks water into the subsoil.  
151	Mr Smith commented on the report from Roscon. After disagreeing with the description of the building’s structure and the permeability of the laneway, where Roscon laid the entire blame on the tree, he disagreed:
“Disagree. If the damage was caused by the tree, which I believe is not the case, 18 months after the Root Barrier was installed (4.5 years ago) the building cracks should have closed. As this was not my observation, the cracking was due to a non-tree root issue.”      
152	That is, it is not due to the roots drying out the soil. 
153	As I said earlier, Mr Smith considered the tree made no contribution to the damage of the house. He considered the primary cause of the damage was stormwater from downpipes flowing onto porous and open surfaces and then to the foundations. 
154	In reaching those conclusions, he noted: 
(a)	the internal damage starts at the front of the house (3 metres from the tree) and to its rear (15 metres from the tree); 
(b) a small tree, with a root barrier in front of it, could not cause damage to that extent; 
(c) the entire north wall has moved about 20 millimetres to the north without any external cracking. This type of movement is common for the end dwelling of a row of terraces where the thermal expansion and seasonal variations add up and push and rotate the end dwelling; 
(d) the elevated moisture levels at the foundations is due to one of two factors. More likely it is due to ponding under the building. Assuming this building has a void under it which is lower that the surrounding natural surface, then the void is fed by the downpipes that discharge beside the foundations; 
(e) the house’s bricks are porous and stormwater will easily pass through them; 
(f) 	there is a likelihood the house is sitting on fill that has been shown to be 600 millimetres deep and may have been uncompacted and is compacting over time; 
(g) the attachment of the extension to the original building exacerbates the damage due to the differences in the depth of the foundations between the two buildings.  
155	He saw pooling of water in the bluestone kerb and channel. This indicated the bluestone drains do not operate efficiently to shed stormwater.  
156	He believes the stormwater from the downpipes on the balcony are causing the damage. To remedy requires a shallow stormwater drain that takes water to the kerb and channel. For the front downpipe, 3.5 metres of PVC or metal pipe “under that area” would be required.  
157	There are two downpipes in the alcove. The downpipe shown in a photograph on page 25 of his first report discharges 25 per cent of the stormwater of the rear extension. For those downpipes, you would dig a shallow trench along the face of the wall and draining to the street.  Those works would take two men two days, $500 of PVC, steel pipe and a permit. The overall cost would be a maximum of $10,000.   
158	Assuming the tree is damaging the property, the purpose of remediation is to return it to being habitable. That requires patching all the damage throughout the building and making good. Depending on the level of finish, that would cost between $50,000 and $100,000. These figures do not include underpinning, as that has already been done, but they include fixing the internal plaster. Once you connected the stormwater system, you would allow 18 months for things to settle before you did the remedial plaster works. The estimate includes the downpipe works. If the downpipes had been connected in 2011/2012, there would be no more damage than that existing then. If taken in 2015, most of the damage would have been avoided. 
159	Photograph 27 on page 392 of the Plaintiff’s Court Book showed how moisture was able to access the foundations because it has nowhere to go. The photograph from Google maps 2009 showed no gutter at the front so that water could pour onto the veranda and get into the foundations. Water comes down the hill into the Telstra pit and flows out of the pit into the soil.    
160	The Hardrock report mentioned the minor rotation. This rotation is now the current failure along the entire length of the building. The end terrace house always suffers with heaving, expansion, contraction and rotation.  
Separate buildings
161	Mr Smith referred to the “Hawthorn report”, which dealt with lightning damage. This report was not in evidence. Apparently, the author suggested the builder of the extension may not have kept both buildings entirely separate.  
162	At page 487 of the Defendant’s Court Book are drawings of an architect, Mr Daly. Mr Smith observed note R4 on drawing 83 does not say what type of malthoid was required. To him, the type of malthoid is critical because the foundation types and depths are completely different for the two buildings. He also observed the malthoid should go to the full depth of the foundation, being 900 millimetres or even deeper. 
163	Mr Smith believes the cause of the damage is settlement “in rotation of the north wall” assisted by the downpipes not being connected to the system. It is settlement of the fill in area which is at least 800 millimetres deep. It is extremely unlikely the tree caused damage after the barrier was installed. Looking at the photographs taken underneath the house, Mr Smith was surprised it is fairly dry. He was very critical of the support for the joists as illegal building works and the floor moves.  
164	Mr Smith disagreed that rain water would go to the bluestone path and then evaporate because the water volume is significant even in a minor storm. The concrete pavers in the alcove are very porous and normally set on sand. Water could seep through them to a depth of 900 millimetres. 
Soil suction
165	Mr Smith saw no factors indicating the presence of soil suction. For soil suction, there must be a difference in moisture content in locations of 15 per cent to 20 per cent. To him, that is not shown in Mr Lawrence’s boreholes with the moisture content of 43.3 per cent in borehole 4 (closest to the front of the building) and 34.2 per cent at borehole 2 (near the alcove). This is a difference of 9.1 per cent.  
166	Mr Smith says the veranda is more recent than 1885 as it has reinforced concrete. He disagreed water has discharged on the veranda since 1885 as it does now. It is highly likely the four cottages drained the same way from veranda to footpath.   
Overall position
167	To Mr Smith, there were four factors to the development of cracks: 
(a)	the building of the extension; 
(b)	the repaving of the laneway, about 2009 or 2010. The laneway was reworked. The underlying soil was exposed. It dried and caused subsidence and rotation of the north wall. As to repaving, he does not know this particular laneway, but laneways were redone in this area and he walked through North Melbourne quite often then; 
(c)	the two saturated areas fed by the downpipes; 
(d) 	the Telstra pit which was recently replaced. The excavation of the conduits provide a route for water because of the lesser compaction around the pipes. It acts as an agricultural pipe. 
168	Mr Smith says the north wall is rotating. Like Mr Eracleous and Mr Lawrence, it is subsiding. He agreed the structural stability of the building has been affected by subsidence of soil causing outward rotation of the northern wall, and cracks in three areas of the western wall are also consistent with subsidence of the northern wall. The cracks on the front door and on the internal wall along the hallway are consistent with the building falling away to the north and west. 
169	With the Telstra pit, Mr Smith is not concerned with water entering through the top of the pit (or the hole in the top), he is concerned about the conduits and the disturbed soil around the conduits. The excavated disturbed soil around the conduits act as a conduit for water to flow through. 
170	Mr Smith implicates the crack or gasp between the veranda and asphalt of the footpath as an entry point for water (and dew) into the soil. He has seen much damage done by very narrow cracks. He did not test this theory, describing the idea of testing as ridiculous. 
171	Mr Smith expected the bottom of the house to be flooded because it was below the height of the surrounding soils and was surprised that it was not.
172	The photograph on page 993 of the Defendant’s Court Book shows a crack in the bitumen migrating towards the house. To Mr Smith, it is due to a combination of the tree roots and heaving. At page 184 of the Plaintiff’s Court Book, Mr Smith accepts the tree is extracting moisture from west side of the house. He doubts the expanding crack at 52 Dryburgh Street is due to the tree because the bluestone laneway provides a very large physical barrier. Based on his experience of the area, the council put a substantial base underneath the bluestone pavers. 
173	Mr Smith does not trust builders to interpret drawings properly regarding materials or install the materials properly. Perhaps he takes a different view if the builder is supervised by an architect. Nevertheless, he thinks the building works for this extension have been generally done well.  
174	Mr Smith commented on a report of Glenn Waters, an arborist. Since Mr Waters’ report was not in evidence, I will ignore Mr Smith’s summary and comments on its contents. 
175	Similarly, he commented on the report of Mr Rodriguez. Only two pages of that report were admitted into evidence. They are of no probative value. Nor are the comments of Mr Smith on the report, except where he reiterates his own opinions. 
Craig Stevens 
176	Craig Stevens is the principal engineer for infrastructure at the defendant. Part of his responsibilities are the footpaths in the municipality. 
177	Exhibit 2 is the defendant’s work order regarding the footpath. The work started on 18 January 2016 and finished on 5 February 2016. Mainly, it was replacing the footpath along that stretch of road. The work was done by Citywide. It has done that sort of work since the early 1990s. The defendant would set the conditions under which it did the work. The defendant does not certify or supervise the work.   
178	Exhibit P is the defendant’s publication entitled “Tree Management”. It contains six sections. The fifth section is entitled “Tree roots and infrastructure” and deals with direct and indirect damage caused by tree roots. Under the former it says: 
“Direct damage is the distortion of built structures as the growing tree root exerts pressure. Direct damage by tree roots is usually limited to light built structures such as pavements and low walls and can also be witnessed in buildings of sub-standard footings.”
179	With the latter, it says in part: 
“Indirect damage is the distortion of built structures as the growing tree takes up soil moisture. Often there are multiple factors contributing to foundation movement and are seldom associated with tree root growth alone. For this reason, claims of indirect tree root damage must be accurately investigated. 
Leaking pipes (as a result of poor construction, old earthenware, cracked and faulty joints and degradation) can create a moisture gradient that encourages tree growth in the direction of the pipe.” 
David Lawrence
180	David Lawrence is an engineering geologist, registered professional geoscientist and a registered building practitioner. He has practised for 34 years. He specialises in the movement and damage in structures, including buildings. He has examined over 5,000 distressed buildings. He is aware of Australian Standard AS2870 for residential slabs and footings. He contributed to the 2011 version. 
181	Mr Lawrence visited the house on 23 September 2019. Robert Livingstone, partner of Dr Livingstone, was present. He had ample access to the house with Mr Livingstone supplying “some verbal background information”. The boreholes were drilled on this visit. Mr Lawrence visited the house again on 9 October 2019. Overall, through boreholes, he obtained soil samples from the laneway and the footpath, on both sides of the barrier. The soil samples were analysed. 
182	Mr Lawrence drilled six boreholes using a hand operated auger. His diagram shows their positions. Using his numbering: 
(a)	number 1: in the laneway near the north-west corner of 50 Dryburgh Street. The soil was moist at 300 millimetres and 500 millimetres. Analysis of the sample from 700 millimetres showed a moisture content of 33.6 per cent. This is wetter than usual. He ascribed some of the wetness to the downpipe. There were “fine tree roots” at 600 millimetres; 
(b) 	number 2: near the alcove of 50 Dryburgh Street. Again, at 300 millimetres and 500 millimetres, the soil was moist and at 700 millimetres, its moisture content was 34.2 per cent, which is slightly wetter than the plastic limit. There were “fine tree roots” at 600 millimetres; 
(c)	number 3: on the tree side of the barrier, opposite 50 Dryburgh Street. At 200 and 600 millimetres, the soil was moist. It was very moist at 600 millimetres and at 700 millimetres it was 26.8 per cent. This is drier than normal or the plastic limit. There were “numerous fine tree roots” found at 700 millimetres; 
(d)	number 4: on the house side of the barrier, opposite 50 Dryburgh Street. At 200 millimetres, the soil was moist and very moist at 500 and 600 millimetres. At 700 millimetres, its moisture content was 43.3 per cent. This is significantly wetter than normal or the plastic limit. There were fine tree roots at 700 millimetres; 
(e)	number 5: on the tree side of the barrier, but opposite the north-western side of 46 Dryburgh Street. At 200 and 500 millimetres, it was moist and at 600 millimetres, 30.7 per cent. Interestingly, at 1600, it was 37.2 per cent; 
(f)	number 6: on the house side of the barrier and opposite 46 Dryburgh Street. At 200 millimetres, moist and at 600 millimetres, very moist with 36.4 per cent at 700 millimetres and 38.1 per cent at 1600 millimetres. 
183	Mr Lawrence took photographs of the exposed soil in each of the boreholes. Each photograph shows the presence of tree roots. 
184	To Mr Lawrence, the results suggest the barrier is effective. With boreholes 3 and 4, samples were taken at 600 or 700 millimetres at what was believed to be the founding depth of the soil. 
185	Returning to the diagram, it includes a drawing of the canopy of a “large vine” and the canopy of a tree in 52 Dryburgh Street.     
186	Inside the house, Mr Lawrence saw the repairs to the cracked plaster at the front and cracking in the second bedroom and the hallway at the rear. Mr Livingstone told him the cracking had become significantly worse in the last six years. The cracking included the second bedroom along the north wall and the rear section of the hallway. 
187	In his report, Mr Lawrence spoke generally about the cause of the distress in certain buildings:
“In general distress in low rise buildings is usually related to movements in the foundation (i.e. the soil supporting the footings). This movement commonly occurs where the foundation is predominantly clay. Almost all clay soils are reactive, that is, they shrink or swell depending on the amount of moisture they contain. When a clay soil is dry its volume will reduce (i.e. it will shrink) and when a clay soil wets up its volume will increase (i.e. it will swell).” 
188	Later, Mr Lawrence set out his views: 
(a)	the initial distress in the original house was caused, in part, by the drying action of the street trees in Dryburgh Street. The other causes are soil moisture issues because the down pipes at the front of the house empty onto the ground; the inflexible nature of the building; the older style unreinforced footing system; the age of the building; seasonal moisture variations; and the building is the last in a row of terraces houses; 
(b)	overall, the movement and distress has been caused predominantly by drying related shrinkage settlements of the highly reactive foundation clays as a result of the drying action of surrounding trees and vegetation;
(c)	the more recent distress is caused predominantly by the drying action of a vine and tree across the lane to the north. In particular, this distress is the cracking at the rear of the original house. This view came from the pattern and location of the movement and distress, the significant growth of the neighbouring vegetation and the tree to the north over the last nine years, the presence of tree roots in the clay soil from BH1 and the adequacy of the bearing capacity of the foundation soils; 
(d)	although the barrier is having a protective effect, it could have been better if the barrier had been longer and deeper; 
(e)	the moisture content of the natural clay soil [layer 3] adjacent to the north western corner of the house is abnormally wet, which is inconsistent with current tree drying settlements in the area. The source of the moisture is the downpipe in the north western corner. This moisture may have caused localised heave; 
(f)	recent movement and distress is partly influenced by the dryness over the last three or four years. By drying the soil it exaggerates the drying effect of the vegetation and trees; 
(g)	the distress is ”influenced” by normal age degradation;
(h) based on his experience, the underpinning and ground injections works have the potential to cause ongoing differential movements and distress;  
(i) to remedy the damage, one must rectify the cause of soil and footing movement, allow the moisture levels to return to a long-term seasonal equilibrium and then carry out cosmetic repairs. The rectification involves either removing the neighbouring tree and vine or placing an “effective” root barrier in the laneway. It also involves replacing the existing street barrier with a suitable barrier and all storm water being removed to a legal point of discharge. One then waits one to two years for the clay’s moisture levels to return to their long-term equilibrium. Afterwards, where required, the timber floor should be realigned. Then the remaining observable distress should be cosmetically repaired.              
189	Using two aerial images from Nearmaps, Mr Lawrence pointed to the growth of the tree and the canopy (involving the vine and tree) at 52 Dryburgh Street between November 2009 and February 2019.
190	There are three layers in the soil profile. At the top, there is a filling of variable depth of crushed rock, sand, silt and clay (layer 1). This discontinuously lies above the “top soil layer” of natural clayey sand (layer 2). Beneath this layer is a highly reactive, high bearing strength natural silty clay soil (layer 3). 
191	Analysis of the samples taken the boreholes revealed: 
(a)	the moisture content of the natural silty clay (layer 3) from BH1 and BH2 is close to the plastic limit. This is similar to the seasonal norm for this type of clay in this area; 
(b)	the moisture content of layer 3 between the tree and the barrier was significantly drier than the plastic limit, consistent with drying by the tree. The same layer from an upper section of BH5 is slightly drier than the plastic limit. While the same layer in the same borehole but in a lower section is slightly wetter; 
(c)	the moisture content of layer 3 from BH4 on the other side of the barrier is significantly wetter than the plastic limit, consistent with leaking pipes; 
(d) the moisture content of layer 3 of BH6 in the upper and lower sections is slightly wetter than the plastic limit, which is slightly wetter than the seasonal norm for this type of clay at that time of year. 
192	Based on the results of a borehole and the age of the building, Mr Lawrence concluded the footing system supporting the original building consisted of about 500 millimetres deep of masonry/rubble-type strip footings. These strip footings are satisfactorily founded on layer 3 with more than adequate bearing capacity.   
193	Mr Lawrence considered BH1 of Smolders did not provide a representative control location because moisture levels were abnormally wet. 
Second report
194	Mr Lawrence prepared a second report, dated 6 March 2020. He was asked to comment on four reports obtained on behalf of Dr Livingstone. They contained nothing of significance which would cause him to change his earlier opinions and recommendations. 
195	Mr Lawrence criticised the third report of Mr Eracleous: 
(a)	assigning one cause without referring to any other cause (that is, other site, building conditions). He does not refer to the barrier; 
(b) the inconsistency between the degree of distress and remedy in section 6.2 and full demolition in section 6.8;
(c)	again, the extent of distress found in the front in section 6.3 is inconsistent with section 6.8; 
(d) he agreed with the conclusion that continuous underpinning of 3.5 metres is impractical and not cost effective. He disagreed with the proposed full demolition because of its potential to cause movement and damage to the house at 48 Dryburgh Street.    
196	To Mr Lawrence, the Hardrock report lent support to his view because he had assumed there was little or no cracking before 2009, when the tree was planted. What happened in 2005 is similar to what is happening now: the descriptions of the crack patterns and the wall movements.
197	Mr Lawrence excavated (using a “test bit”) midway along the northern wall near the alcove and found the footing was about 500 millimetres below the level of the bluestone laneway. 
198	Mr Lawrence says there are factors contributing to the damage:
(i)	the tree had some initial impact on the movement, particularly at the front;
(ii)	more recent movement towards the rear of the original house is caused by the drying action of the vegetation on the property across the laneway;
(iii)	storm water leaking into the soil (mainly at the front);
(iv) 	relatively inflexible nature of the solid brick construction; and
(v)	the older style footing system which tends to transmit any soil movement directly to the structure increasing the level of distress.   
Soil suction
199	Mr Lawrence described soil suction as a measure of the energy required to remove a water molecule from a clay molecule.  As to its diagnostic value, he said:
“So it’s an interesting concept scientifically but in terms of diagnostically it’s fraught because soil suctions are affected by so many other factors. They’re affected by the mineral content of the clay. So if it’s a potassium rich clay or a calcium rich clay it’s a different suction. They’re affected by the moisture content of the clay, So a high moisture content clay will have a lower suction and a lower moisture content will have a higher suction. So it’s proportional. They’re affected by depth as well and they’re affected if there’s other material in the clay such as sand or silt particles. So soil suction and matrix suction is used in an academic sense but in terms of being particularly useful diagnostically it’s – it’s fraught in my opinion.”
200	Mr Lawrence rejected the way to measure the impact of the tree is by soil suction. He does so partly because it is an academic approach even though the Australian Standard refers to and accepts soil suction. He believes the Australian Standard is mistaken in putting emphasis on soil suction. 
201	During cross-examination, Mr Lawrence returned to soil suction. He elaborated on moisture and suction:
“So high suction just means you’ve got a low moisture content, and a low suction means you’ve got a high moisture content. It doesn’t necessarily mean there’s trees present… 
The relevance in this case is that he’s [Eracleous] comparing it to the suction from the – soil that’s got a high moisture content. So the – that’s why the suctions are not meaningful is because he’s comparing it to a saturated or very damp moisture.”  
Telstra pit
202	With the Telstra pit, Mr Lawrence noted the backfill in and around trenches tend to be more porous than the natural clay. 
Neighbouring tree and creeper
203	To Mr Lawrence, the most recent and severe damage is towards the back of the original building. The crack patterns showed wall rotation to the north and perhaps slightly to the east, consistent with drying in the northerly direction. BH2 encountered fine tree roots. These findings suggest the drying action is caused by neighbouring vegetation.
204	Mr Lawrence did not enter the rear yard of 52 Dryburgh Street to examine the tree or the vine (creeper). What he saw was from the laneway. Judging from the two Nearmap images, Mr Lawrence believed that, since 2009, the tree and vine (creeper) canopy had increased by more than 100 per cent. With the creeper, there is a canopy of 15 to 18 metres. The amount of water taken by trees, etc, is directly proportional to the size of the canopy:
“Is that a significant size? – Yeah. So the transpiration or – which is the amount of water that the trees and vegetation remove out of the soil is directly proportional to the surface area of the leaf canopy so – because the suction is exerted by transpiration out of the leaf surface. So the larger the leaf surface area – combined leaf surface area, the greater potential for soil to be dried by that – that vegetation.”
205	The tree roots in his BH2 is more likely to come from the neighbouring tree than travel the 10 or 12 metres from the front. He added the pavers are relatively impermeable.  
206	Photograph 2 on page 392 of the Plaintiff’s Court Book shows moisture from the downpipe going into the gap. There is slight mould and moss shown.  
207	Mr Lawrence has no reason to doubt the front downpipe has discharged in that way since 1885. Nor did he doubt rainwater drained from the eastern roof of the original building in the same way since 1885. He disagreed there had been no change in the building since 1885 on the basis of the Hardrock report in 2005. He maintains that water out-letting onto soils adjacent to buildings on reactive clay sites is one of the main causes of damage. But he does not think excess of moisture is the main cause of movement and damage here. It has contributed but is not a primary cause. He agreed that Mr Smith’s emphasis on the wetting of soils is inconsistent with the damage Mr Lawrence saw. 
208	He saw tree roots on the house side of the barrier (in BH3).  He believes they came from the tree. The variation in moisture content caused the damage. He maintains the abnormally wet conditions of the soil are due to the downpipes with Smolders finding high moisture content in the alcove area. 
209	At paragraph 37 of his first report, he postulates a plumbing leak for the elevated soil moisture. He says when he used the word “plumbing” he was referring to the downpipes.  
210	He focussed on the back and north side of the original residence because it had by far the most significant cracking. The owners raised this cracking. Most of the front cracks had been repaired when he inspected. However, most of the damage to western wall is consistent with rotation to the north and inconsistent with rotation to the west.  Whether the footing is 500 millimetres or 900 millimetres nearly makes no difference. Mr Lawrence says the footing is founded on natural clay with adequate bearing capacity. The building is not supported on rubble but clay.   
211	It is common to have water percolate through trenches because of the stone and backfill. Mr Lawrence agreed water will flow downhill through the trench. He believes the effect of the membrane of the barrier would have a minor effect in trapping moisture on the uphill (house) side. Nevertheless, he believes the downpipe is the main factor for elevated moisture on the house side of the barrier. He maintains an amount of water would be going through the gap between the fascia and bitumen. It is water trickling down the fascia that would enter the soil. The barrier has some trapping effect from water from the downpipe at 50 Dryburgh Street and the other properties even though downhill. He visited the premises after a period of minor rainfall. It is this rainfall that is absorbed in the soil. 
212	At paragraph 49 of his first report, Mr Lawrence says the horizontal component of the cracks in the north-western corner is evidence of localised heave. An example of the pattern is shown in the photograph at page 430 of the Plaintiff’s Court Book. However, photograph 11 on page 281 of the Plaintiff’s Court Book does not show a heave crack. It is a crack indicating rotation to the north, which is consistent with drying.   
213	The cracking shown in the photographs on pages 444, 445, 446, 447, 448, 449, 450, 451, 452, 453 and 454 in the Plaintiff’s Court Book were either filled in or had masking tape over them when he inspected. He does not know if the photographs on pages 452 and 453 are of the first bedroom. He thinks the photographs on pages 454 to 457 are of bedroom 2. In the Hardrock report (at page 472), there is a fine crack where the wall looks out onto where the alcove is. 
214	Mr Lawrence did not agree the building showed no significant distress before 2009:
“Even though there’s evidence from the owner to say that? – Um, I think there would be periods where the building would perform – would appear to perform well. But also given the age of the building, the – the type of footing and the type of clay, there’d also be periods when there would be more cracking evident.”   
215	He is unconvinced using Google to assert the house was in good condition. 
216	The tree root barrier is not deep or long enough. It does not protect against roots migrating under the laneway. He agrees roots need not be next to particular soil before the effect of suction can be measured. The tree sets up a negative gradient and moisture in the soil diffuses from a high concentration to a low concentration. The moisture content in BH1 of Smolders was extraordinarily high and in BH2 was above the plastic limit but lower, so you got a suction differential. High suction just means you have high moisture content and low suction means high moisture content. This can occur without the presence of trees. Suction here is not meaningful because Mr Eracleous is comparing it to a saturated or very damp moisture. 
217	The presence of efflorescence means there has been water in the area through the brickwork or from the soil. The mineral salts accumulate but fall off after four or five years and dissolves into the soil.   
218	With the pavers, water would seek cavities/spaces between the pavers rather through the pavers themselves. The amount flowing through the lane and the amount going into the soil is a function of the volume of water. 
219	Although Uretek is a common solution, if asked in 2015 Mr Lawrence would have recommended against its use.
220	In re-examination, Mr Lawrence re-affirmed his evidence the tree roots in BH2 most likely came from the vegetation across the laneway. He saw tree roots in all boreholes and it was likely the roots in the boreholes in Dryburgh Street came from the tree. He measured the footing in the laneway from the surface to the base of the footing at 500 millimetres. It is the backfill in the trench, not the Telstra pit, which allows moisture to pass through. The backfill is more permeable than the natural clay and affecting the moisture content across the front walls. The main reason for the elevated moisture content is the downpipes. Why now:
“… So the downpipes, even if they’re been there for 130 years, they’re still causing maximum variation between the seasonally wet condition because they’re outletting water into the soil and the seasonally dry condition … and sure that would’ve been happening for 130 years but it depends on the seasonal factors. Sometimes if you had a seasonally dry period you could get a bigger difference in the amplitude of the moistures but the fact that they’re been outletting there for a long period of time, it still means that they’ve been causing significant variations in the moisture content over that time.”
221	The millennium drought gave higher instances of cracking in buildings. He thought the cracking was more significant at the back of the north side of the original building and did so on the basis of what the Dr Livingstone’s partner told him.        
Legal considerations 
Causation 
222	As I said earlier, the central issue in this case is causation: did the tree cause or materially contribute to the damage of the original building? Plainly, causation is central to whether there has been a substantial and unreasonable interference with Dr Livingstone’s use and enjoyment of her house. 
223	There is no necessity for the search of a sole cause in every case. There are cases where more than one cause is responsible for the damage. In March v E & MH Stramare, Mason CJ said:
“Nonetheless, the law’s recognition that concurrent or successive tortious acts may each amount to a cause of the injuries sustained by a plaintiff is reflected in the proposition that it is for the plaintiff to establish that his or her injuries are ‘caused or materially contributed to’ by the defendant’s wrongful conduct.”  
224	McHugh J said:
“Moreover, a negligent act or omission will be held to have materially contributed to the damage if its contribution was not de minimis.”  
225	In Henville v Walker, Gaudron J said:
“There is nothing novel in the idea that, on occasions, loss or injury is the result of two or more events, neither of which is sufficient, of itself, to bring about that result. The events in question may be sequential or concurrent. March v Stramare (E & MH) Pty Ltd was a case involving an injury which resulted from the conjunction of two separate acts or events, the injury in question having resulted from the plaintiff, who was driving at excessive speed, running into a negligently parked vehicle. 
For the purpose of the law of negligence, where two or more events combine to bring about the result in question, the issue of causation is resolved on the basis that an act is legally causative if it materially contributes to that result. The same is true for the tort of deceit …”
226	I may add it is also true for the tort of nuisance. 
227	In Roads and Traffic Authority v Royal, Kirby J said:
“Fourthly, where, as is sometimes argued to be the case several acts or omissions on the part of the contesting parties are alleged to be causes -in-fact of a claimant’s damage, the resolution of the contest presents a question of fact that is itself to be decided by reference to the foregoing considerations. The search is not necessarily for ‘the’ cause because, in some cases, two or more factors may be found to have contributed in a legally relevant way to the damage that occasions the action. If, by the foregoing criteria, a conclusion is reached that two or more causes have played a part in causing the damage, legal liability will attach so long as a nominated cause is held to have ‘materially contributed’ to that result. The position under Australian law was correctly described in Henville v Walker by McHugh J: 
	‘If the defendant’s breach has ‘materially contributed’ to the loss or damage suffered, it will be regarded as a cause of the loss or damage, despite other factors or conditions having played an even more significant role in producing the loss or damage. As long as the breach materially contributed to the damage, a causal connection will ordinarily exist even though the breach without more would not have brought about the damage.’” (citations omitted)
Competing causes 
228	The defendant submits it is necessary to determine the extent to which each competing factor contributed to the front damage and then discount the contribution of the other factors. It relies on a paragraph from the Judgment of Slattery J in Michos v Council of the City of Botany Bay, which cites the first two paragraphs at page 489 of the Judgment of Hodgson J in Proprietors Strata Plan 14198 v Cowell:
“It is necessary in this case to decide what part of the loss claimed was due to the fig tree roots and what part was caused by natural forces. Such an apportionment is permitted in the authorities.”  
Nuisance 
229	Dr Livingstone relies primarily on the tort of private nuisance. There is a helpful examination of the tort in the Judgment of his Honour Judge Parrish in Marshall v Berndt, where his Honour refers to the Judgment of Preston CJ in Robson v Leischke.  Relevantly, the tort requires: 
(a)	an act or omission which is an interference with, disturbance of or annoyance to a person in the exercise or enjoyment of her ownership or occupation of land and is only actionable on proof of special damage;
(b)	generally, liability for nuisance is not strict. It involves fault. The type of fault varies depending on whether the defendant created it or adopted or continued a nuisance. Where it has created the nuisance, fault depends upon the defendant’s conduct and state of knowledge;
(c) where the defendant created the nuisance as opposed to adopting or continuing it, and where the defendant knew or ought to have known that in consequence of its conduct harm to the plaintiff was reasonably foreseeable, then it was under a duty of care to prevent such consequences as are reasonably foreseeable.
230	I was referred to City of Richmond v Scantelbury. That case dealt with a defendant which had inherited, not created, the nuisance and the legal position is different. However, there is this passage in the Judgment of Kaye J which is relevant here:
“In the absence of evidence to the contrary, it is a reasonable presumption that the defendant discharges its responsibilities as custodian and manager of the park by its competent officers or employees who are possessed of knowledge concerning matters of common knowledge concerning soil in the municipality and the properties of elm trees in the natural order of things.”
231	I also would assume the defendant’s officers or employees knew of the existence of clay in this area of its municipality. They knew of clay’s highly reactive nature. They knew of the moisture-seeking propensities of trees through their roots. They knew the characteristics of the white cedar and its potential for growth.     
Contributory negligence
232	The defendant raised contributory negligence of Dr Livingstone. This defence is available in cases of nuisance, including private nuisance.
233	In Stockwell’s case, Gillard J explained the nature of the obligation resting on Dr Livingstone:
“The law recognises an obligation resting upon a plaintiff to exercise reasonable care for his safety and that of his property. If a plaintiff fails to take reasonable care for his own safety, property or interests and that lack of care is a cause of the incident which caused the loss or has contributed to the harm, the plaintiff is guilty of contributory negligence. Contributory negligence is not a defence, but results in an apportionment of responsibility leading to a reduction in the amount of damages.
The burden rests upon the defendant to prove contributory negligence, and the issue is one of fact.
The defence not only relates to acts or omissions which contribute to the wrongful act but also concerns a failure to exercise care, which contributed to the extent of the harm resulting from the wrongful act …”
Mitigation of loss
234	The defendant also raised mitigation of loss. The duty to mitigate a loss applies to nuisance. The duty is that of the plaintiff but the onus of proving a failure to do so lies on the defendant. However, one must be careful in assessing this issue. As Lord Macmillan said in Banco de Portugal v Waterloo & Sons Ltd:   
“Where the sufferer from a breach of contract finds himself in consequence of that breach placed in a position of embarrassment the measures which he may be driven to adopt in order to extricate himself ought not to be weighed in nice scales at the instance of the party whose breach of contract has occasioned the difficulty…The law is satisfied if the party placed in a difficult situation by reason of the breach of a duty owed to him has acted reasonably in the adoption of remedial measures, and he will not be held disentitled to recover the cost of such measures merely because the party in breach can suggest that other measures less burdensome to him might have been taken.”        
Notice 
235	Dr Livingstone must prove she put the defendant on notice about the nuisance and the council’s failure to take appropriate action once on notice. The defendant relies on Holloway v Newcastle City Council referring to (2008) 72 NSWLR 98 at [42].
Discussion 
Pre-existing damage to the property 
236	What was the extent of the damage to the original building in 2009? 
237	Dr Livingstone was happy with the house’s condition when she bought it in 1997. It was re-roofed and she saw no damage after its completion. In 2005/2006, the extension was built. There were some works performed on the existing house: plastering of minor cracking in the internal rear wall; repainting; polishing of floors. After the building of the extension, she saw very minor cracking at the rear of the original house. By 2009, the cracking remained the same, very minor. There was no cracking at the front of the house.  
238	On 17 February 2005, Mr Ackland of Hardrock saw diagonal cracking in the rear wall of the house. In his location plan, it is described as a “fine crack”. The cracking was confined to one area and described in the singular. I would infer the cracking was very minor. Mr Ackland ascribed this cracking and the minor rotation of the north wall to the highly reactive foundation soils and the shallow foundations. Given the age of the building, one would not be surprised at that conclusion. 
239	Between March 2006 and 2009, Dr Livingstone had no issues with the state of the house, including cracking. Despite this, Mr Lawrence does not exclude the existence of significant distress to the building in that period. The notion of the building performing well and not well in different periods and cracking becoming more evident may be so, but it does not assist where Dr Livingstone made no observations between 2006 and 2009 and started making observations from 2011 or 2012 and onwards. 
240	When Mr Smith and Mr Lawrence examined the house, they saw damage similar to that described in the Hardrock report, that is, diagonal cracking. Naturally, there is a world of difference between the damage they saw and that apparently seen by Mr Ackland in 2005.  
241	On Dr Livingstone’s evidence, she saw cracking in 2005, and in the rear section in 2009 and 2011, but there was no cracking of any significance in the period from March 2006 until the planting of the tree in 2009. 
242	I accept her evidence. The original building was in good condition prior to the planting of the tree. 
Notice
243	Judging from Exhibit P, the defendant was aware loss or damage could follow the planting of trees. Dr Livingstone approached the defendant time and again from about 2012 complaining about the tree and the damage she alleged it caused. The defendant was given ample notice.  
Tree root barrier 
244	The barrier was installed in September 2015. It runs the width of 50 Dryburgh Street but no further. It does not enter the laneway. It is made of concrete and is 1.5 metres deep. Its installation cut those roots reaching towards the house. Afterwards, suckers started to erupt in the footpath. Following complaint, the defendant sent a person to eradicate the suckers. The treatment was temporally successful but they reappeared, sprouting in a few places. In four emails, Dr Livingstone or her husband complained to the defendant, told the Council of the presence of an “active sucker”, the growth of two saplings, the sending of suckers despite the barrier, and culminating in:
“… the tree has lifted the root barrier out of its way. The cracking is rapidly making my front door inaccessible and we are showered with dust every time we walk through the front of the house.”     
245	The barrier is not wide enough. Mr Lawrence agreed its width would not prevent roots from travelling around its northern edge and then under the laneway. Theoretically, its roots could extend around the northern edge of the barrier. However, there is no evidence that they have.  
246	Mr Eracleous considered the barrier was too shallow to prevent tree induced drying and suction. The roots would have access to the house in the way described in the Roscon report. 
The experts 
247	I heard from three experts. Each identifies a different primary cause for the damage to the house: Mr Eracleous, soil suction; Mr Smith, the downpipes; and Mr Lawrence, the tree and vines at 52 Dryburgh Street. Both counsel criticised the evidence of these witnesses. 
248	The defendant submitted about Mr Eracleous: 
(a)	His experience is inferior to that of Mr Lawrence. He has given evidence in court on six occasions and none involved tree roots. However, in the past five years, he has inspected 300-400 properties affected by tree root drying suction. A very low number involved a problem with a barrier, but Mr Eracleous does not say the barrier here is the problem. 
	It is true Mr Lawrence has been practising in the building field for longer than Mr Eracleous, but both are experienced practitioners. There reaches a point where more experience, by itself, means little or nothing.
(b)	He shows confusion about the remedy by affirming and then denying the need for underpinning. I do not understand his evidence as showing confusion as much as showing development in his reasoning and conclusions. 
(c)	He lacks the detail in his reports compared with the reports of Mr Smith and Mr Lawrence. His first two reports were aimed at identifying the cause of the damage. They were not aimed at potential litigation. Both Mr Smith and Mr Lawrence were engaged for the purposes of qualifying themselves to give evidence at a trial. It is unfair to criticise Mr Eracleous in this way. His third report discusses the scope of the remedies. On a reading, none of his reports was composed with litigation at the forefront
(d) He claims to have considered factors not set out in his report. This is not an issue of credit. It points to an inadequacy of his report in that it does not allow the court to assess fully his opinions on the basis of the reports alone. However, that was overcome through his oral evidence. 
(e) He lacks the same understanding of the effect of neighbouring vegetation as Mr Lawrence. This assumes that vegetation is relevant. Mr Eracleous did not think so.  
(f) He has not complied with Expert Witness Code of Conduct by having regard to the Hardrock report but not mentioning it. Again, this failing was raised in his oral evidence and dealt with.  
(g) He does not display the care of an expert witness by giving evidence he said he should not give – the progress and direction of tree root growth. It is unfortunate expert witnesses do stray beyond their areas of expertise. Mr Eracleous was not the only expert who was guilty of this failing in the case. Again, it is an issue for the court ultimately.
249	None of the criticisms affect my willingness to assess his opinions at their face value.   
250	Dr Livingstone’s counsel attacked Mr Smith, submitting I should prefer the evidence of Mr Lawrence to his evidence. He identified several grounds: 
(a)	Mr Smith is a master of all trades but is “light on actual paid employment”;
(b)	he substantiates his experience by the use of the expression “in my experience”. The example given is his parking near bluestone laneways on his way to the station and had a good look at them;
(c) his estimate of costs calculated minutes before getting into the witness box.
251	I consider none of the points is valid. Mr Smith has had a varied career in the building industry. It is long and broad. Far from justifying a variation on “Jack of all trades…”, it is this breadth which makes him an interesting witness. 
252	The criticism in (b) is really an expression of counsel’s frustration with him, due to him having an answer to most things. All that tells me is that he is across his field of expertise.
253	The criticism in (c) is unfounded. Issues arise during the course of a trial, and witnesses are asked their opinion on the briefest of notice. It is a question of the weight given to the opinion, rather than a criticism of the witness himself.    
254	The criticism of Mr Lawrence was muted. Principally, it was that his reports are inadequate in that they do not address the damage to the front of the house. Dr Livingstone’s counsel suggested reasons. The suggested reasons are unworthy. The broader criticism is unwarranted. A combination of his written and oral evidence made clear that Mr Lawrence saw the neighbouring vegetation as being predominantly responsible since 2015 for the entire damage to the original building, including the western end.    
Causation 
255	The central issue is one of causation. It is whether the tree caused or material contributed to the substantial and unreasonable interference with Dr Livingstone’s use or enjoyment of her property. 
256	The cause of an occurrence is a question of fact to be determined by applying common sense to the facts of each case. The act or omission must have materially contributed to the damage suffered, which may be the case even if other factors have played a significant role.
257	If one adopted Mr Lawrence’s view, it cannot be proved that “but for” the tree Dr Livingstone would have suffered damage. Even if the tree caused some damage, it does not follow the damage it caused increased significantly since the installation of the barrier. All experts agree the barrier severed the roots.  
Roscon
258	Mr Orangi of Roscon inspected the house on 8 January and 28 February 2018. He saw structural cracks in the façade of the front of the house. Inside, he saw “multiple” large cracks (up to 7 millimetres wide) in the original building. Based on his 25 years of experience as an engineer in the building industry, he attributed both sets of cracks to the tree. 
259	He nominated one or other of two mechanisms to explain why tree roots in the vicinity can cause movement in the foundation soil: 
(a)	through the growth in cross-sectional size thereby exerting upward pressure on the footings; or
(b)	the roots will absorb much of the moisture in the foundation soil which causes shrinkage or subsidence.  
260	In any event, he considered the root barrier inadequate.    
Soil suction
261	To Mr Eracleous, soil suction explains why the tree is influencing movement some 15 metres away. The following questions and answers explain his view: 
“Q: If a tree is projecting a sucking influence onto a property but it doesn’t have a drying effect, and that is to say for whatever reason the soil of the property is still moist, then the suction effect alone will not cause damage to a property or its foundations? – I don’t understand why it wouldn’t. 
Q: I’m putting it to you that it wouldn’t. Do you disagree? – Yes, I do disagree, because the fact that there’s a suction means that the moisture is being drawn away from it and there’s a variation. As soon as we get a variation of suction between one region and another we’re going to get differential movement. The characteristic surface movements that are defined in the Australian Standard are related to suction, they’re not related to moisture.”      
262	Smolders measured moisture content and suction in its two boreholes. The results are set out in its report. On the limited evidence of the boreholes, there is no clear correlation between the moisture content and the soil suction. In borehole 1 (alcove), the soil suction between 0.5 metre and 2 metres is reasonably constant, varying between 3.4 and 3.6 pF. While the moisture content varies between 30.9 per cent and 49.6 per cent. In borehole 2 (north west corner), the soil suction varies between 3.6 to 4.04 pF while the moisture content is reasonably constant between 28.1 per cent and 30.5 per cent. 
263	The normal soil suction in Melbourne is about 3.5 picofarads. The difference in readings for boreholes 1 and 2 are large. The magnitude of suction at the front of the house is 4.5 times greater than that at the alcove. That is abnormal suction, and is caused by the tree. There is no other site factor which could cause that suction effect.
264	Mr Eracleous said the pattern of cracking was consistent with the house tipping to the north and this was consistent with drying of the soil. 
265	Mr Eracleous relies on soil suction. Certain readings lead him to lay the cause of the damage at the feet of the tree. He does not say the tree is the sole cause. He says it is a “significant contributing factor”. He did not explain what he meant by the expression. In the usual meaning of those words, it means an important factor contributing to the damage. This would constitute a “material contribution”, of which the High Court spoke.  
266	Soil suction is not a theory of Mr Eracleous lacking broad acceptance. Measurement of it is required by the relevant Australian Standard. The content of an Australian Standard is very widely accepted among relevant professionals. So much emerges from the adherence to them by various experts in this case. The variation of suction from one region to another creates differential movement in the soil. 
267	However, Mr Lawrence says Australian Standards were mistaken in putting emphasis on soil suction. The soil suction is theoretically interesting, but is diagnostically fraught because the degree of soil suction is affected by other factors: the mineral content of the clay; the moisture content of the clay; the depth of the clay; and the mixture of other substances in the clay (for example, sand or silt particles). 
268	In adopting that view, Mr Lawrence stands apart from the general view of experts in this area, for soil suction is an issue with the relevant Australian Standard. 
269	Describing the use of soil suction as “academic” tells me nothing as to why he rejects the approach. If the science behind the concept is valid, then there is no apparent reason why it should not be used in the field. That seems to be the approach of the Australian Standard by incorporating it in the standard. 
270	The factors raised by Mr Lawrence seem immaterial unless they combine to render measurement of soil suction unreliable. Mr Lawrence does not say that. The presence of other minerals in clay means the extent of the suction differs from, perhaps, pure clay. Similarly, the composition of the clay itself or its moisture content means the same thing. 
271	Mr Lawrence equates high suction with low moisture content and vice versa. To deny meaning to Mr Eracleous through his use of soil with high moisture (saturated) content does not make sense. On his reasoning, the existence of an area of high moisture content and another with a lower moisture content should be expected if there is a difference in soil suction between those two locations.      
272	The presence of soil suction in an Australian Standard suggests its recognition nationally as a legitimate measure. To say there are complicating factors does not mean measurements cannot be taken or the results of analysis are unreliable. Those factors suggest that there will be variability between soils in the level of suction. Such variability does not impact upon the ability to measure soil suction accurately.      
273	I see no basis to reject the opinion of Mr Eracleous based on soil suction. To him, moisture content is immaterial. Earlier, I quoted this sentence from his oral evidence:
“The characteristic surface movements that are defined in the Australian Standard are related to suction, they’re not related to moisture.”
274	Despite the results of Smolders’ analysis of the borehole samples not supporting the proposition that the level of moisture is proportional to the level of suction, both Mr Lawrence and Mr Eracleous maintain that it is -- the drier the soil the greater the suction and vice versa.        
275	The essential criticism was the location of the Smolders’ boreholes, which seems unreasonable. So long as the boreholes were placed at locations relevant to the building, it should not matter whether they were in areas of high moisture content. What is important is the measurement of soil suction at different locations and whether the measures are of significance. According to Mr Eracleous, they are because:
“The characteristic surface movements that are defined in the Australian Standard are related to suction, they’re not related to moisture.”  
276	It is noteworthy that Mr Lawrence’s second borehole (BH2) was drilled in the laneway, near to the alcove while Smolders’ borehole 1 was drilled in the alcove.  Even borehole 1 of Hardrock was drilled at what became the western edge of the alcove.    
277	Mr Smith did not consider the issue of soil suction until he was asked about it by counsel. By speaking of percentage differences in moisture content, Mr Smith appears to be using a shorthand method of assessing the importance of soil suction by referring to the moisture content of the soil. He did not speak about soil suction in terms of the measurements in picofarads. Mr Eracleous did. The highest picofarad reading was 4.05 in BH2 at a depth of 1.8 metres with a moisture content of 30.5 per cent. At 2 metres in BH1, the corresponding figures were 3.4 pF and 49.6 per cent. Even on Mr Smith’s analysis, the difference between 49.6 per cent and 30.5 per cent is 19.1 per cent. Even though he was not asked, presumably, on those figures, he would accept the significant presence of soil suction at least at depths below the footings. I do not place any reliance on this aspect of Mr Smith’s evidence. 
278	I am satisfied that soil suction generated by the tree played and is playing a critical role in the damage caused to the original building. From a causal perspective, soil suction is a very material contributor to the damage to the original building. 
Neighbouring vegetation 
279	Mr Lawrence says the predominant cause of recent distress is the vine and tree at 52 Dryburgh Street. This property is across the bluestone laneway. His reasons are: 
(a)	the most recent and severe damage is towards the back of the original section;
(b)	the crack patterns are consistent with drying in a northerly direction, that is, the settlement of the northern wall is due to drying of the foundation soil;
(c)	borehole 2 found fine tree roots. [Hardrock found tree roots in 2005]. These are more likely to have been from the tree at 52 Dryburgh Street than travel 10 or 12 metres from the front;
(d)	since 2009, the canopies of the tree and creeper have grown significantly. 
280	As to (a), this assumption is incorrect. It is based on a personal communication from Mr Livingstone. I did not hear from Mr Livingstone. In any event, Mr Lawrence relied on his understanding of Mr Livingstone’s opinion. 
281	Given the state of the front of the original house in 2018 and 2019, it is incorrect to assume that the state of the damage to the rear of the building was more significant when Mr Lawrence inspected notwithstanding the communication from Mr Livingstone. The photographs of the interior at the front depict a shocking state of affairs. This caused Dr Livingstone to arrange for underpinning works in 2019. The then state of the rear of the house was shocking enough, but not as bad as the front.   
282	When Mr Lawrence attended, most of the cracks to the front façade had closed after the underpinning by Uretek. The 2019 underpinning works also saw the plastering over of internal cracks in the front of the original building. Photographs taken in 2018 show severe damage to the front. From my perspective, I would have thought these cracks were more severe than those at the rear of the original building. Certainly, the cracking has significantly worsened since the installation of the barrier.  
283	As to (b), both Mr Eracleous and Mr Lawrence largely are of the same view: there is settlement or subsidence in the north wall due to the drying of the foundation soil there.  
284	As to (c), Mr Lawrence found fine tree roots in his borehole 2.  He spoke of the suction exerted through transpiration through a leaf canopy of 15 to 18 metres with the impermeable bluestone laneway acting to extend the influence of the roots as they move further afield seeking moisture.  
285	As to (d), Mr Lawrence did not enter the rear yard of 52 Dryburgh Street to examine the tree and vines. He looked at such of the canopy that showed itself above the boundary fence. He relied on two images from Nearmaps to demonstrate the growth of the tree and vines between 6 November 2009 and 22 February 2019. His report contains three other overhead images: from Google Earth Pro dated 4 March 2006; Nearmaps dated 12 October 2009; and Nearmaps dated 15 September 2015. The last image does not show the entire rear yard. Nevertheless, those three images seem to show a static coverage of foliage. Although the image of February 2019 is not very clear, it does appear to show a significant expansion of a canopy from the earlier images, with it progressing into a fenced area to the east of the property.      
286	I have referred to Mr Lawrence’s diagram at page 33 of his first report. It contains an overhead view with the vine and tree. It does not purport to be to scale and, frankly, tells me nothing of value on this issue.  
287	I do not know the distance of the tree in 52 Dryburgh Street from the northern wall of the original house. I know the width of the laneway is about 5 metres. 
288	Smolders drew a diagram of 50 and 52 Dryburgh Street. It was not to scale. It depicted seven bushes along the southern boundary of that property, described as “extensive Wisteria creeper”. These bushes start at a point opposite the alcove and proceed in an easterly direction to a point midway along the new extension. It also depicts a tree, said to be 8 metres high, set back from the southern boundary and opposite the last two bushes as one proceeds east. The tree is not named. 
289	During cross-examination, Mr Eracleous gave the impression he looked closely at the vine and tree. He spoke of the height of the vine as 3 metres and its distance from the original building as 5 metres. Similarly for the tree, it was 7 or 7.5 metres high and 10 metres from the original building. By saying the distance of 10 metres, he is placing it 5 metres from the southern boundary of 52 Dryburgh Street.           
290	Reliance upon an external view of the tree and vine and an estimation of the effect of their tree roots has distinct weaknesses. Owing to a lack of expertise, Mr Lawrence is not in a position to speak about the extent of the root system of the vine, even if he knew what sort of vine it was. 
291	Mr Eracleous spoke of a zone of influence. His justification was that the concept was used in the Australian Standard. The theoretical zone of influence of trees is equal to 1 or 1.2 times their mature height. He did not think this formula applied to shrubs or vines. If it did, then the vine was 3 metres high and its roots were well away from the building. He, too, was in no position to express that view in relation to the vine.    
292	I do not know the type of tree in the rear of 52 Dryburgh. If Mr Eracleous measured the distance, it is 5 metres from the boundary. Otherwise, I do not know. The one thing I do know is the width of the lane. The Smolders’ diagram gives its position in the rear yard of the property. Since the diagram is not to scale, I cannot use it to locate the tree in the yard.   
293	Mr Lawrence introduced a different concept. He spoke of the size of the leaf surface of the tree and vine, of transpiration, and said the amount of water removed out of the soil is directly proportional to the surface area of the leaf canopy. Broadly:
“So the larger the leaf surface area – combined leaf surface area, the greater potential for soil to be dried by that – that vegetation.”   
294	It seems he assumes all leaves are much the same and the desire for moisture of the leaves of a vine or creeper is much the same as it is for a maturing tree. It also seems the Australian Standard does not use this concept of transpiration.  
295	The Nearmap view of the foliage is from above. This view gives no idea of the vertical. As with many vines or creepers, their foliage may consist of a thin, widespread layer. On the other hand, trees usually have branches shooting out from the trunk at different levels. The horizontal coverage of a tree may not be great but its volume of leaves would be much greater than that suggested by an overhead view. For all that is known, the extent of foliage on the tree in 52 Dryburgh Street may be greater than that of the vine. This consideration makes Mr Lawrence’s use of transpiration suspect. 
296	I do know Mr Lawrence found fine tree roots in his borehole 2. They were living roots. Hardrock found them in 2005. Neither discovery gave the quantity of the roots. Absent an expert opinion, I am unable to make any finding about their extent or influence.  
297	As is plain, Mr Eracleous relied on soil suction. Only when pressed did he speak of the zone of influence. He rejected the tree and vine in 52 Dryburgh Street because the soil suction in the alcove or bin area was 3.4 pF, which he said was very low. As there is no exacerbated soil suction there, he rejected the influence of the neighbouring vegetation.   
298	To recap. Borehole 1 of Smolders was drilled in the alcove. At depths of 0.5, 1.0 and 2.0 metres, the soil suction measured in picofarads was 3.40. At 1.50 metres, it was 3.60. It was the enlarged readings at borehole 2 which led Mr Eracleous to implicate the tree. Since the soil suction in the alcove is low, then, according to Mr Eracleous, the vegetation is not affecting the building. I accept that view.  
299	I would not find that the tree and vine in 52 Dryburgh Street are the predominant cause of the damage to the original house, as Mr Lawrence contends. In fact, I go further and say the evidence does not enable me to find they make a material contribution to the damage. In summary, I do so for these reasons: 
(a)	the evidence relied upon by Mr Lawrence as to the nature of the vegetation is too imprecise to allow me to accept his opinion concerning coverage and transpiration;
(b) in any event, the concept of coverage of the canopy contrasts with the concept of zone of influence. The latter appears recognised in the Australian Standards, the former apparently is not;
(c) the cracking pattern told both Mr Lawrence and Mr Eracleous the same thing about the north wall: it was settling towards the north;
(d) it is clear from my earlier reasons, I accept the concept of soil suction and its application in this case. Mr Eracleous rejected the influence of the vine and the tree, relying on the “very low” soil suction reading from the alcove.      
Downpipes 
300	Mr Smith considered the northern wall had moved 10 to 20 millimetres to the north and the entire northern portion had subsided by about 20 millimetres towards the laneway. He believed the stormwater from the downpipes caused heaving and the observed damage. The primary cause of the damage was stormwater from the downpipes flowing to the foundations. 
301	There was much evidence about the downpipes at the north west corner and in the alcove. Water from those pipes spills onto the veranda and the tiles of the alcove. There was evidence about the way water would enter the subsoil from the veranda and the subsoil from the tiles and the laneway. At first sight, the mechanisms described by the defendant’s witnesses were unlikely to have any significant effect. However, Mr Lawrence drilled a borehole 6 near the north western corner of 46 Dryburgh Street. On analysis, at 700 millimetres, there was 36.4 per cent moisture, and at 1600 millimetres, 38.1 per cent. By contrast, borehole 1 was drilled near the north western corner of 50 Dryburgh Street but in the laneway. Again, on analysis, it showed 33.6 per cent moisture at 700 millimetres. Borehole 4 was drilled on the footpath opposite the western wall and revealed 43.3 per cent moisture at 700 millimetres. Borehole 2 was drilled in the laneway near the western edge of the alcove. It revealed 34.2 per cent moisture at 700 millimetres.         
302	With Smolders, it drilled two boreholes: at the north west corner and at the alcove. In each, it analysed for moisture at four depths. In BH1, they varied between 30.9 to 49.6 per cent and, in BH2, between 28.10 and 30.50 per cent. BH1 was drilled in the alcove, while BH2 on the veranda near the north west corner.  
303	The first thing to recall is that the downpipe in the north western corner has been discharging in the same manner for upwards of 125 years (until 2011). Apparently, those discharges had not caused damage.  
304	These results lend some support to the effect of the stormwater upon the subsoil, especially in or about the alcove. It is more likely that most of the water from the downpipe in the north western corner would flow over the veranda, onto the footpath and then to the kerb. A lesser amount would flow over the veranda, down the front of the fascia and enter the soil through the gap between the fascia and the asphalt of the footpath.  
305	The better view is that the damage to the interior walls (including the northern and western) is due to the rotation of the northern wall caused by settlement or subsidence of the foundation soils. This is the view offered by Mr Lawrence, Mr Eracleous and, possibly, Mr Orangi. The flow from the downpipes causes localised heaving only. 
306	Approached from a different direction, Mr Smith maintained the tree could not cause the damage. Throughout his evidence, he described the tree as “small”. With the root barrier between it and the front of the house, it could not cause damage to the front of the building and to a distance of 15 metres from it. From the exhibited images, I would not call the tree “small”. Up to a point, the size of the tree is unimportant. It is its position relating to the house which is important. No one suggests that its roots have reached the eastern end of the original building. 
307	It might be thought the high moisture content of the boreholes at the northern side is inconsistent with the supposed drying effect of those tree roots. However, I do accept the impact of the downpipes in elevating the moisture content. Mr Lawrence assigned only a local effect of any heave caused by the swelling in the foundation soils due to the high moisture content. It is agreed the north wall has subsided. Whatever heave exists has been overwhelmed by the subsidence. As a cause of the damage, the effect of the downpipes, both in the alcove and at the north west corner is marginal.
308	Consistent with his view of the cause of the damage, Mr Smith thought there would be an accumulation or pooling of water underneath the original house. There was not. The evidence about efflorescence is a very long way from the existence of pooling. Curiously, the lack of pooling did not cause Mr Smith to change his opinion. Since pooling was an expected outcome of his view, its absence is a reason to doubt his view of the significance of heaving as a cause of the damage to the original building.    	   
Telstra pit    
309	Mr Smith saw the pit as full of water when he inspected the property. It introduces water to the front of the house. Mr Lawrence says the pit is not a gathering point for water. It will dissipate in a north to south direction and away from the house. But he says water passing through or collecting near the pit will contribute to the damp soil around the foundations. I accept that the pit makes a contribution to the moisture level of the soil. It too is marginal.  
Malthoid barrier     
310	It was Mr Smith’s view there was no indication on the building plans that the malthoid barrier had been installed or, if installed, to an appropriate depth. Mr Eracleous assumed the malthoid barrier had been installed and there could not be differential movement due to the interaction of two different footing systems. 
311	The extension is a separate building from the original building. The plans for building the extension required a malthoid barrier. There was much discussion about whether the barrier was installed and, if it was, what exactly was installed. The discussion was speculative. Absent a proper evidential basis justifying a contrary finding, I would infer a malthoid barrier was installed according to the plans. Accordingly, there is no basis to conclude the difference in the footings of the extension and the original building is contributing to the damage to the latter.  
Sunlight
312	Mr Eracleous identified soil suction as a “significant contributing factor” to the damage. The only other factor he mentioned was the exposure to sunlight of the northern wall. As with the effect of the downpipes, the effect of sunlight is subsumed into the overriding effect of soil suction.    
Overall      
313	Mr Eracleous relies on soil suction. Mr Lawrence does not believe soil suction is a useful diagnostic feature. I do not know whether other experts hold that view. If others do, then they are in a minority for soil suction is adopted by Australian Standards, which has widespread expert support. Mr Smith’s criticism of soil suction is rudimentary and, possibly in this case, mistaken on his own figures. There is no valid reason for me to reject the opinion of Mr Eracleous. 
314	The factual basis underpinning Mr Lawrence’s opinion about the neighbouring foliage is slender and I am not prepared to accept his view.
315	Mr Smith’s view of heave and subsidence due to the reaching of the plastic limit is rejected or discounted by Mr Eracleous and Mr Lawrence. Heave is inconsistent with the existence of settlement, subsidence is not. However, Mr Smith predicted the pooling of water underneath the floorboards because the soil there would be lower than the surrounding soil. It appears the soil there is lower but there was no pooling. Mr Smith over-estimated the effect of the downpipes in the alcove. 
316	I do not find that the effect of the downpipes is a material contributor to the damage of the original building. 
317	Mr Orangi is correct to implicate the tree, but largely for the wrong reason. I say “largely” because the tree’s roots are still affecting the front of the original building despite the barrier. However, he identifies two reasons related to the roots as causing the entire damage but does not implicate the effect of soil suction, which is the major causative factor.  
318	Overall, I find the damage to the original building at 50 Dryburgh Street was due to the tree. It is the sole cause. There were other factors identified, for example, the nature of the footings and the age of the building. These matters are not causes in the legal sense. They are the underlying weaknesses upon which the true cause worked.  
Findings on nuisance
319	The defendant planted the tree. The tree has caused or materially contributed to the damage of the original building. The defendant is guilty of the tort of nuisance. It has substantially interfered with Dr Livingstone’s enjoyment of the original building. She has suffered and will suffer special damage. The defendant ought to have known that damage would arise from the planting of this tree so close to an old building where the foundation soils are clay and highly reactive. Damage was reasonably foreseeable. It is liable in damages.   
Contributory negligence 
320	The defendant pleaded contributory negligence. As pleaded, there were four particulars of her alleged negligence: 
(a)	failing to seek professional assistance/advice concerning the state of the property and any remedial action required in a timely manner; 
(b) failing to undertake any necessary remedial action in a timely manner or at all; 
(c) failing to properly maintain the property; 
(d) failing to heed professional advice that was received in a timely manner or at all.  
321	During counsel’s final submissions, this allegation was refined to two areas of Dr Livingstone’s contributory negligence: 
(a)	her failure to prevent stormwater discharge into the underlying soil. It submitted the extent of her contributory negligence would reduce the defendant’s liability to nothing;
(b) her failure to take steps to address the damage once it became apparent to her. Before 2015, she did not engage any experts to tell her why the damage was occurring. She did not have any works undertaken. Each of Mr Smith, Mr Lawrence and Mr Eracleous say most of the damage could have been avoided if remedial steps had been taken earlier. 
322	Whether referrable to contributory negligence or mitigation of loss, according to Mr Kirkwood, the cost of connecting the stormwater downpipes to a legal point of discharge would have been $27,000 to $28,000 if it had been done at the time of the building of the extension. 
323	Regarding (a), this submission fails because I do not consider the discharge from the downpipes made a material contribution to the damaged suffered. 
324	Regarding (b), Dr Livingstone submits that before 2015 she sought professional help by calling the defendant. There is merit in the submission. Exhibit P is a publication of the defendant. Its intended audience are residents of the City of Melbourne. The exhibit makes clear the defendant was well aware of the problems to buildings posed by tree roots. The exhibit sets out a procedure for raising these complaints. Throughout the document are references to arborists and the defendant’s access to them. Presumably, it had access to structural engineers.  
325	It would have been improper for Dr Livingstone to remove the tree or dig up the footpath and interfere with underground services in order to alter the discharge of water over the footpath.  
326	Uretek is a well-known commercial product offered at a reasonable cost. In 2015, the triggering issue for Dr Livingstone was the sticking of the front door. It led to her April email and to the engagement of Uretek. The use of Uretek by Dr Livingstone was reasonable. The fact that it proved ineffectual does not mean she was negligent to any degree by adopting that course. 
327	For completeness, Dr Livingstone said she could not afford such steps then, even though earning about $180,000 a year. She is not impecunious in the accepted meaning of that word. 
328	Dr Livingstone was not negligent.  
Duty to mitigate 
329	The defendant has not satisfied me that Dr Livingstone failed to mitigate her loss. She sought the help of the defendant. The defendant planted the tree. It held itself as having expertise with trees. It was planted in its municipality. It ought to have known the nature of the foundation soils within it. It was reasonable for her to approach the defendant and harbour the hope it would rectify the problem. This was a reasonable step, and it did result in the barrier. She engaged Uretek and, later, Heinemann. 
330	These attempts can be seen in either of two ways. First, she engaged in abatement which did not involve going onto the defendant’s land. As such, the rule against recoverability of costs does not apply. Second, her actions are better characterised as mitigating her loss than abatement of the nuisance. The fact that the Uretek treatment was unlikely to have improved the situation does not detract from her action being reasonable. In 2018 and 2019, the original building was in a dreadful state. The engagement of Heinemann was an attempt to prevent further damage.   
331	Although Mr Lawrence and Mr Eracleous considered the work of Uretek was unlikely to have improved the situation, nevertheless, it was reasonable for Dr Livingstone to engage Uretek. It was a widely used and inexpensive remedy. 
Quantum of damages 
332	Mr Eracleous recommends demolition and rebuilding of the original building. He is the only expert of the four (including Roscon) that does. I have accepted his explanation of the cause of the damage to the original building. Criticism of his confusion about what is exactly required is without merit. Read properly, he is not confused. His third report was a clear attempt at determining what was to be done. It represents his thought out position after determining the causal factor. I accept his recommended remedy. Mr Pavey was instructed to cost on the basis of demolition and rebuilding and I accept his costings. 
Uretek
333	Uretek charged $6,561.50. Dr Livingstone shared the cost with her neighbours at 48 Dryburgh Street equally and paid $3,280.75.  
Storage 
334	The defendant submitted there is no evidence to support Dr Livingstone’s belief that the roof was likely to fall in. As such, her decision to store the furniture was a discretionary choice or preference. Dr Livingstone said she stored contents of the two rooms because she wanted to protect them from falling masonry. Judging from the photographs in 2018, and her description of the state of the original building then, her belief was reasonable. The state of the cracking is appalling. An objective observer might well have wondered whether the roof would fall. Storing the contents of the two rooms away from the house was reasonable, for there was insufficient room elsewhere in the house to do so.  
Cost of expert reports 
335	The defendant submits the costs of the reports of expert consultants ($14,740) are legal costs and not claimable as part of the damages. 
336	Although there was evidence of the amounts paid by Dr Livingstone to remedy and store items, for some reason, there was none about the costs of the experts she engaged. Their invoices were not tendered. In the absence of evidence, I cannot allow the amount of $14,740 as part of her special damages.    
Negligence 	
337	Dr Livingstone did not pursue her claim of negligence against the defendant. Assuming for the sake of argument there was a duty of care owed by the defendant to her about the tree root barrier, there was no evidence establishing the defendant’s placing of the barrier was negligent in the manner particularised.   
Jones v Dunkel 
338	Dr Livingstone invoked Jones v Dunkel over the failure of the defendant to produce its file on 50 Dryburgh Street. She submitted there was a file and referred to a 1999 survey. She further submitted it would have thrown light on the state of the property before the planting of the tree. 
339	Despite Mr Lawrence’s concession the file would have contained information of the kind contained in the Hardrock report, its contents are too speculative for me to conclude that its production would be expected of the defendant. I draw no inference.  
Conclusion 
340	Despite forming part of the prayer for relief, removal of the tree did not form part of Dr Livingstone’s opening or closing addresses. 
341	Dr Livingstone is entitled to damages in the sum of $435,510.08 made up as follows: 
(a)	Uretek (her share), MJW and Heinemann: $39,965.08; 
(b)	removal of items: $1,000.00;
(c)	13 months of storage: $4,202.00;
(d)	further storage for 12 months: $3,912.00;
(e)	cost of returning stored items: $1,000.00;
(f)	cost of accommodation while the house is demolished and rebuilt: $41,600.00;
(g)	cost of demolition and rebuild: $346,830.00. 
342	 I will hear the parties on the questions of interest and costs.