Keith Albert Lionel Holloway and Or v Newcastle City Council
[2013] NSWDC 62
•16 May 2013
District Court
New South Wales
Medium Neutral Citation: Keith Albert Lionel Holloway & Or v Newcastle City Council [2013] NSWDC 62 Hearing dates: 10/12/12 - 13/12/12 Decision date: 16 May 2013 Before: Mahony SC DCJ Decision: Verdict for the Defendant
Catchwords: Nuisance; alleged encroachment of tree roots Legislation Cited: Civil Liability Act 2002
The Trees (Dispute Between Neighbours) Act 2006Cases Cited: Robson v Leischke (2008) 72 NSWLR 98
Rylands v Fletcher (1886) LR 3HL 330
Burnie Port Authority v General Jones Pty Limited (1994) 179 CLR 520
Sedleigh-Denfield v O'Callaghan [1940] AC 880
Torette House Pty Ltd v Berkman (1940) 62 CLR 637
Montana Hotels Pty Ltd v Fasson Pty Ltd (1986) 61 ALJR 282
City of Richmond v Scantelbury (1991) 2 VR 38
Proprietors of Strata Plan No 14198 v Cowell (1989) 24 NSWLR 478
Delaware Mansions Ltd v Westminster City Council [2002] 1AC 321
South Australia v Simionato (2005) 143 LGERA 128Texts Cited: Clerk & Lindsell on Torts 19 Ed Category: Principal judgment Parties: Keith Holloway - 1st Plaintiff
Wendy Holloway - 2nd Plaintiff
Newcastle City Council - DefendantRepresentation: A Justice - Plaintiffs
D Priestley - Defendant
NPR Legal - Plaintiffs
Moray & Agnew - Defendant
File Number(s): 10/338579 Publication restriction: Nil
Judgment
The Plaintiffs' Claim
The plaintiffs are the owners and occupiers of premises at 62 Drysdale Drive, Lambton which they purchased in 1995. In 1996 the plaintiffs built their home on the property.
At the rear of the property was land owned by the defendant ("the Council") which is contiguous with Roberts Circuit, Lambton and the southern boundary of the plaintiffs' property. The plaintiffs allege that in 1997 the defendant, by its employees, agents or servants, planted on that land a number of trees, some of which were planted within a few metres of the plaintiffs' property. At all material times since, the Council has been responsible for the growth, care and maintenance of those trees.
It is the plaintiffs' claim that roots from those trees have encroached onto the plaintiffs' land, extracting water and moisture from under the foundations of the plaintiffs' home, which led to shrinkage of the soil undermining those foundations and causing part of the plaintiffs' house to flex on its foundations differently from the rest of the house, giving rise to a torsional force which caused damage including cracking in the brickwork and pavement and misalignment of windows and doors within the property.
A further problem allegedly caused by the tree roots was that a sewer pipe at the rear of the premises was broken and leaked water, which it is alleged, further exacerbated the damage.
In 2009 the rear of the plaintiffs' home was underpinned in order to prevent further damage occurring. Unfortunately this was not successful in that further damage has occurred in other areas of the house.
The plaintiffs' claim is brought in nuisance. The plaintiffs have pleaded that since October 2009 the Council has been aware of the nuisance and has failed to abate the continuing nuisance to the plaintiffs' property. Whilst the plaintiff pleaded that the Council, by its servants or agents, planted the said trees in or about 1997, and has at all material times since that date been responsible for the "growth, care and maintenance of the trees", it has not been pleaded that the Council was negligent in doing so. Rather, the plaintiff's claim is that the Council's liability in nuisance arises from notice given to it on or about 26 October 2009 of the nuisance and its failure thereafter to "abate the continuing nuisances".
The plaintiffs' damages are said to include the abatement costs in respect of installation of a root barrier along the rear boundary of their property, together with rectification costs. The rectification costs are claimed for two periods, namely, the work carried out due to damage to the property which was rectified in 2009, and secondly, rectification costs for damage since that work.
The Council's Defence to the Claim
The Council has denied the fundamental factual contention of the plaintiffs that the damage to their home was caused by roots from the trees planted by the Council in 1997. The Council alleged that there were numerous other factors causing differential changes in the soil on the plaintiffs' property. That soil it was alleged was highly reactive clay. The Council claims that the footings on the property were not adequate to provide proper support for the house, given the reactive soil type. Further, the Council contends that the evidence does not exclude mine subsidence as a cause to the house damage, given that the property was built in a mine subsidence area.
In respect of the fractured sewer pipe, the Council contends that it was not armed with knowledge of this event, did not know when it had happened, or how much water had escaped. In respect of the underpinning works carried out in 2009, the Council contends that that work had the effect of firmly fixing the house at the location of those works, but allowed other parts of the house to flex, thereby causing further damage.
The Council further contends that the underpinning work carried out in October 2009 was inappropriate in that air vents were created which provided ventilation under the house which led to drying of the soil under the middle of the plaintiffs' home. Whilst the original damage was caused at the rear of the premises, the damage now being exhibited was located in the middle of the house.
The Council has also pleaded that the claim is an apportionable claim within the meaning of s 34 of the Civil Liability Act 2002 ("CLA") and that the builder, W J Harris Constructions Pty Limited and/or Mr W J Harris, is a concurrent wrongdoer within the meaning of that section, as are CSG Engineers Pty Limited and/or Mr Rex Henderson, who designed the footing system for the house. Further, the defendant pleads that CSG Engineers Pty Limited and/or Mr Steven Savage and/or Mr Bruce Fletcher were also concurrent wrongdoers in respect of work carried out by Ironmate Pty Limited in July/August 2009, and therefore the defendant relies on s 35 of the CLA with respect to apportionable damage for concurrent wrongdoers.
The Council also pleads contributory negligence against the plaintiffs in respect of the stormwater drainage on the property not being adequate, and the leaking sewer pipe referred to above at the rear of the premises which the defendant alleges was not repaired in a timely manner.
The Issues in the Case
As defined by the pleadings, the issues in the case are as follows:
(1) Did the planting of trees by the Council, adjacent to the southern or rear boundary of the plaintiffs' property constitute an actionable nuisance on the plaintiffs' property by way of the encroachment of tree roots onto the property subsequent to the planting of the trees?
(2) Has the Council become liable for the nuisance by actual or constructive knowledge of it since October 2009?
(3) If so, what damage was caused by the nuisance?
(4) If the nuisance caused damage to the plaintiffs' house, is the plaintiffs' claim an apportionable claim between other concurrent tortfeasors pursuant to s 34 of the CLA?
(5) If so, having regard to the role played by other concurrent tortfeasors, what is an appropriate apportionment to be attributed to the defendant pursuant to s 35 of the CLA?
(6) Did the plaintiffs contribute to the damage by way of their own negligence?
The Plaintiffs' Evidence
Mr Keith Holloway gave evidence by way of two affidavits affirmed on 22 September 2011 and 6 November 2011. The first of those affidavits sets out the history summarised above. Mr Holloway was an impressive witness whose credit was not attacked. Unless otherwise indicated, the following summary of his evidence contains my factual findings in relation to the history of the matter which were largely uncontroversial.
In late 2005 Mr Holloway noticed damage in the south-western corner at the rear of his house. That included cracking of the external brickwork, cracking and separation in the internal gyprock and cornices, doors that would no longer close and cracking in tiles, together with the separation of external concrete ramps and paving from the building. He engaged MPC Consulting Engineers ("MPC") to conduct a report to determine the cause of the damage to the house. That report dated 28 February 2006 was annexure C to his affidavit (page 8 of the Plaintiffs' tender bundle). The report followed an inspection conducted on 16 February 2006 by a senior structural engineer employed by MPC. It involved a visual inspection of the observed damage to the property, and lists 11 separate defects. The report noted that in the area where the house was built there were clay soils with moderate reactivity. However, MPC opined that the observed defects were not likely to be attributed to reactive clay movement and it was noted that the reactivity of the soil should be confirmed by a geotechnical engineer who could assess the soil at the rear of the property to ascertain its properties under varying moisture conditions.
The report noted that the house was located in a recognised mines subsidence zone and went on to state:
"The nature and extent of the defects observed during MPC's inspection is consistent with gradual "curvature" movements at the rear (south end) of the property. These are typical of movements due to mine subsidence, and tend to damage non-structural building elements with limited flexibility and strength in the plane of the movements (brickwork, cladding, glazing, internal partitions). They also tend to cause joints to open and close, as well as causing windows and doors to jam."
The report of MPC went on to note that the footings had been certified as "safe, serviceable and repairable as per mine subsidence guidelines for a 5.00m pothole design". The report went on to state:
"Mine subsidence is the likely cause of the defects sighted during MPC's inspection. On the basis that the observed damages have occurred in a localised area of the residence and are consistent with possible round subsidence. The movement of the foundation soil has been predicted and accounted for in the design of the footing system (which was approved by the MSB). However, the degree of articulation of external walls does not appear to be adequate."
The report noted that the damage observed was typically "non-structural" damages and was not expected to have a detrimental effect on the structural integrity of the residence in the short term. MPC engineers therefore recommended a claim be made against the Mines Subsidence Board ("MSB"), and a geotechnical engineer be engaged to assess the soil type, reactivity and moisture content of the soil at the rear of the property, as well as provide a confirmation that the soil movements are due to mine subsidence and thirdly, to contact MPC for further advice once those two matters had been attended to.
In March 2006 Mr Holloway made a claim with the MSB to have the damage to the house rectified. An inspection was carried out by MSB of the house in March 2006 and a report prepared in which the MSB found that mine subsidence was not the cause of damage to the house. The report went on to state that damage to the property had been caused by:
(1) Eccentric settlement of foundation material (clay) aggravated by:
(a) different foundation bearing values exist across the property ...
(b) water run-off and water seepage from adjoining properties are affecting the site ...
(c) the existing footings of the dwelling have been designed safe, serviceable and repairable ... the footing design is by a certified structural engineer ...
(d) extended legs of the concrete footing at the rear of the dwelling are found in too shallow foundation material (clay).
(e) penetrometer results revealed very loose foundation material ...
(f) no reinforcement exists between concrete bays of the rear paving."
By letter dated 31 March 2006 the MSB refused Mr Holloway's claim (annexure F, page 34).
Mr Holloway claimed that by August 2006 the damage to the house was becoming worse and he retained geotechnical engineers, Douglas Partners, to undertake an investigation as to the cause of that damage. By report dated 29 August 2006, Douglas Partners advised their investigation "indicated no obvious cause of the damage". They suggested a number of additional steps to be taken, namely:
"Undertake structural assessment of the existing footings with respect to both adequacy for Class H conditions as well as for spanning a five metre pothole.
Verify the depth of the existing footings and the founding strata, in particular along the southern portion of the western boundary. This would require removal of the concrete paving and excavation of shallow pits to the base of the footings;
Assess the possible presence of a pothole forming below the site. This may require the drilling of a bore/bores using a mechanical drilling rig."
Mr Holloway took no further action until January 2009 when he retained CSG Engineers Pty Limited ("CSG") to identify the source of the damage. The report of CSG dated 21 January 2009 is exhibit H to his affidavit, page 52 of the tender bundle. Those engineers found that the following were "contributing factors" to the damage:
(1) "No direct mines subsidence likely, however some settlement within the zone of influence may have occurred. This, if correct, is a minor contributor and we do not believe that the MSB is likely to contribute funds.
(2) The site is 'H' class, however, in the absence of other factors your residence should be able to accommodate normal 'H' class movement.
(3) Vibration from construction works may have also contributed, especially in the formation of initial hairline cracks that have subsequently grown. This would be hard to prove and relies solely on your statement.
(4) The alteration of the drainage and planting of trees would be a major contributing factor. Trees within a distance of 1.5m times their height of a building reclassifies the site as a 'P' site (problem site), in recognition of the effects of evapotranspiration drying. As you raised your concerns with Council at the time of planting you should have a case for Council assistance in mitigating your problems. We would estimate the drainage/trees are 50% of the problem. Even if you do not wish to pursue this matter with Council we strongly advise that you put them on written notice of your concerns, as the trees are likely to cause greater problems in time as they grow taller.
(5) We estimate that the pipe contributed in the order of 25% of the damage. This may be covered under your insurance and they may assist in the repair component of your costs."
CSG went on to recommend certain repairs to the property and recommended the installation of "a proprietary root barrier along the rear boundary fence (preferably to the outside) to a qualified arborist's design (minimum 2m deep and minimum 3m beyond the sides of the house). Council should assist or entirely carry out the design, approval and installation of this". The building work was carried out by Peter Sharman, builder, and the scope of works is set out in the quotation from Ironmate Pty Limited which is dated 20 March 2009 and is annexure "I" (page 55 of the plaintiffs' tender bundle). It did not include the root barrier referred to.
In October 2009 Mr Holloway retained CSG for the purpose of providing a report for the Council. That report is exhibit J to his affidavit (page 56). The report noted that despite the underpinning work, the residence had continued to drop and was suffering further damage. It went on to state:
"We write to you because it is our belief, that the principal cause of the previous damage and more importantly the ongoing damage, is due to the presence of large trees in the Council reserve at the rear of the property. Obviously if these trees predated the residence, then it would have been the owner/builders and engineers responsibility to take their effect into account and design accordingly. However, it was sparse grassland at the time of construction and for several following years, with adequate drainage. Subsequently, developments including the introduction of fill, construction of a road and significant tree planting has dramatically changed the subsoil characteristics."
The report annexed a document published by an organisation known as "The Foundation and Footings Society". The report went on to state:
"It can be seen from the above that there are many factors supporting the argument that the trees are the principal cause of damage. Of additional interest is that there was reportedly no observed damage preceding the year that the trees were planted and that we understand that several other neighbouring residences have similar damage to the rear portions of their residences also."
This report was followed up with a further letter to the Council dated 8 February 2010. The correspondence sought a response from the Council, otherwise it stated that the plaintiffs would begin to explore "legal avenues". No response was forthcoming from the Council to that letter.
On 3 August 2010 solicitors instructed by Mr Holloway wrote to the Council advising that it had now been over nine months since the Council was informed of damage being caused by the roots from trees planted on Roberts Circuit, Lambton and that no action had been proposed or commenced by Council to stop that damage occurring. The letter advised the plaintiffs' intention to commence proceedings for damages for the tort of private nuisance unless the Council responded within 14 days. The Council responded by letter dated 9 August 2010 saying that the claim had been referred to Council's Insurance Brokers. By letter dated 13 August 2010 (annexure P, page 75) the Council advised that the claim had been forwarded to the Council's insurers for investigation and that the investigation was "currently underway".
A further quotation was obtained from Ironmate Pty Limited under the hand of Peter Sharman, builder, dated 12 February 2011 as to the cost of proposed works to the sub-floor area (annexure Q at page 76).
In his second affidavit affirmed on 6 November 2011, Mr Holloway annexed the invoices he had paid for consultancy services provided by MPC, Douglas Partners and CSG, together with evidence of payments totalling $21,424.00 to Peter Sharman, builder, for work performed as detailed in invoices dated 3, 5 and 10 August 2009.
The cross-examination of Mr Holloway established that at the time he and his wife built their home, Drysdale Drive was open country and in fact was the site of the former drive-in theatre. Roberts Circuit, at the rear of the premises, did not exist.
Mr Holloway had first noticed the broken PVC sewer pipe over 10 years ago (ie. prior to 2002) and he did not know how long it had been broken for as there was no outside indication of the leak. He arranged for repair of the pipe and moved the toilet to a different part of the house.
Mr Holloway acknowledged that Douglas Partners had advised him that there was no obvious cause of the damage to his home, and that their report did not state that the damage had been caused by tree roots. He also acknowledged that the report obtained in February 2006 from MPC suggested that mine subsidence was the likely cause of the damage and that report did not identify tree roots as a possible cause thereof.
Notwithstanding that CSG had recommended three underpins to be carried out, in fact, four were built to support the back of the house. After that work was carried out Mr Holloway knocked a few bricks out so as to provide under floor ventilation. At the time he did that in 2009 he noticed that the soil under the house was very wet. In respect of storm water drainage, Mr Holloway gave evidence that in times of heavy rain a lot of the run-off came from the property next door. There was an above-ground swimming pool on that property. The reason Mr Holloway had taken the bricks out to provide for ventilation was:
"A: To let airflow under the house to dry it out as a result of the pool next door."
The reason Mr Holloway had not constructed the root barrier was that he:
"A: Hadn't got around to it."
The plaintiffs relied on the evidence of Mr John Ford, a consultant botanist who affirmed two affidavits on 10 October 2011 and 25 September 2012. His first affidavit annexed a report dated 3 August 2011 which contained his opinion that following his inspection of the property on 17 February 2011, in his opinion, the damage caused to the property was caused by roots of the eucalyptus trees situated on the Council's property at the rear of the premises. He identified those trees as eight eucalyptus trees within 10 metres of the Holloway's dwelling, the closest being four metres from the boundary.
Mr Ford took samples from tree roots that he located penetrating the foundations and following laboratory analysis, was able to identify them as roots from eucalyptus trees. His inspection of the front of the house, where there were no trees situated close by, showed no signs of damage.
It was Mr Ford's opinion that roots of the eucalyptus trees situated on the Council's property had been a major factor causing the damage to the plaintiffs' property. The damage was caused by differential water extraction from highly reactive clay soils, the roots had disrupted the footings resulting in the cracking and displacement. It was entirely unsuitable in Mr Ford's opinion for such large trees to be located in close proximity to a dwelling house. He recommended a root barrier of sufficient dimensions to prevent any further root ingress to be constructed on the Council's side of the southern boundary of the plaintiffs' property to protect it from further damage.
In cross-examination Mr Ford conceded that he had not considered the question whether drainage might be relevant to the moisture levels in the highly reactive clay soils. He was not asked to look at drainage or different drainage levels. In fact he only considered tree roots as a cause of the damage to the house and did not consider any other cause. For example, he did not consider the question of lack of ventilation or sources of water. It was put to Mr Ford that it was inevitable that he would come to the conclusion he did, because he was not looking for any other cause. He said that as he was not an engineer, it was not for him to comment on engineering matters such as the adequacy of the footings. He conceded in crossexamination that he was not able to say how likely it was that the trees had caused the damage exhibited to the property.
Mr Ford's second affidavit affirmed on 25 September 2012 responded to two affidavits relied on by the defendant, those of Lindsay Field and Daniel Page. In his opinion, the critical time for water extraction by roots was during the dry season when the roots would be extracting moisture from the underlying clay and thus causing the clay to shrink. That shrinkage would in turn cause a drop in the foundations in the rear of the house where the roots had penetrated.
In respect of the proposition that it was inevitable that he would come to the conclusion set out in his report, given that he was not looking for any other cause of damage to the house, Mr Ford gave the following evidence:
"A: Well it's not my field to look for other things. I mean, I'm not an engineer so I'm not going to be looking for any damage to or problems with the foundations. I work as a botanist. My brief was essentially to come and analyse the site, see if there were tree roots there and if there were, and in my opinion if that supported what is stated in the brief. Well that's essentially what I did."
He was also asked as follows:
"Q: You are not able to say how likely it is that those trees have caused damage to the house, are you?
A: No, it's - it's probably possible to state the actual likelihood. I mean 50%, 100%; I don't know, but I would probably think of other causes. I mean when I looked at that I saw that the damage was mostly or only in the back part of the house, not in the front part of the house. I went into the house and saw the damage, inspected that and I was aware that there were no trees on the plaintiffs' property, there were no trees at the front. There were trees at the back in quite close proximity."
Mr Ford did not conduct any tests of moisture content of the soil on the site and therefore was unable to form any view about the dryness of the soil in the area of the property near the Council's trees, as opposed to the northern end of the plaintiffs' property.
Nor could Mr Ford give evidence of the depth of the roots as he could not actually get under the house.
Mrs Wendy Holloway swore an affidavit on 14 February 2012 in which she deposed to a visit at the premises by a Mr Daniel Page, who was employed by the Council. She allowed Mr Page to take certain photographs of the external cracking to the brickwork and in the laundry of the premises in late 2009, following which, he said words to the effect of:
"I haven't seen anything like this before."
Mrs Holloway was not cross-examined.
Mr Peter Sharman swore three affidavits on 9 November 2011, 20 September 2012 and 3 December 2012. He was the builder who provided a quotation for works to the plaintiffs on 20 March 2009 and carried out that work in August 2009, following which, he was paid the sum of $21,424.00.
On 12 February 2011 Mr Sharman again inspected the premises and provided a quotation for repair and rectification of damage that he observed, and to insert a root barrier. Annexure D to his affidavit was the quotation for carrying out those works dated 12 February 2011. Annexure E, is a quotation of the same date for works to repair the concrete in the backyard of the premises that was raised for inspections of the property connected with the proceedings. In his affidavit sworn 20 September 2012, Mr Sharman responded to the report prepared by Mr Robert Barker of Barker Harle, dated 23 November 2011, relied on by the Council.
In his affidavit sworn on 3 December 2012, Mr Sharman responds to a further report prepared by Mr Barker of Barker Harle dated 16 November 2012. The second and third affidavits sworn by Mr Sharman therefore deal with evidence relevant to the question of damages, which are referred to below.
In cross-examination Mr Sharman agreed that he was not asked to advise what works were suitable or appropriate for the site at all, when he first carried out rectification work in 2009. Nor was he asked to investigate the causes of the damage to the house.
Mr Sharman did give evidence of the use of adjustable piers which were commonly used in the area to allow for upwards and downwards movement of soil underneath residential houses. He agreed that on this site there had been quite a lot of irregular ground movement over a number of years and therefore, in the event that adjustable piers were used, they would require adjustment three or four times a year. This is because of the reactive nature of the underlying clay and soil.
In the event that a semi-permeable membrane was used to stabilise moisture content in the soil, there would be less need to adjust the piers. In re-examination it was established that there were between 32-36 adjustable piers, according to the original council approval for the footings on the property. The amount of adjustment, or the need to adjust some or all of those piers, depended on the levels they were set at and the flex of the building. This was shown in exhibit A, the Council building approval 95/1573.
Mr Waring-Flood is a Civil Engineer who prepared two reports upon which the plaintiffs relied. They were dated 26 September 2012 and 27 November 2012.
Mr Waring-Flood was the principal of AWL Engineering Pty Limited, upon whose letterhead his two reports appear under. He had previously been employed by CSG and had been the author of the reports from CSG to the plaintiffs. In his report dated 26 September 2012 Mr Waring-Flood noted that CSG had excluded as possible causes of the damage to the plaintiffs' house mine subsidence, past roadwork activity, poor construction or inadequate footings and bearing failure. He noted that CSG engineers had concluded that the trees were the principal cause of the damage, meaning the trees planted by the Council at the rear of the plaintiffs' property. He had observed those trees to have "rapid growth" over the three years prior to his report.
It was Mr Waring-Flood's opinion that the tree roots had caused the damage exhibited to the property in four steps. First, the tree roots had sucked water from the clay which had dried out and shrunk thereby no longer providing support to the foundations closest to the trees. This caused the footings to drop, a situation which was exacerbated by the MSB requirement for outrigger footings at the rear of the premises closest to the trees which may have also acted as weights to pull the footings down. Secondly, the differential movement of the footings at the rear of the premises had caused the sewer to crack and leak. This water was distributed unevenly throughout the sub-floor area causing the ground to heave or swell and causing damage to the building.
Thirdly, the sewer leaked for an unknown duration and this period of wetting the sub-floor soil encouraged root growth towards the residence. Fourthly, the plaintiffs had investigated installing a root barrier on his advice and he took up that issue with the Council on their behalf. Until that device was set in place to stop root suction, in the opinion of Mr WaringFlood, the residence would continue to deteriorate.
The report of Mr Waring-Flood made it clear that tree root suction was the principal cause of the damage, and that the footings for the property were not the cause of the damage. Whilst his first report on behalf of CSG to the plaintiffs attributed a figure of 50% of a possible damages attributable to trees, it was now his opinion that the trees had contributed to even more than 75% of the damage, "being much closer to 100%".
In his subsequent report dated 27 November 2012, Mr Waring-Flood responds to the report of Mr Robert Barker of Barker Harle Consulting Engineers dated 16 November 2012. In his conclusion, Mr Waring Flood noted the following areas of disagreement between himself and Mr Barker, namely:
(1) That the tree roots are the major cause of damage.
(2) That the design was reviewed by the "By Engineering Principles" part of the Building Code.
(3) That inadequacies of the footing design have had an impact on the performance of the footings.
(4) Whether improved sub-floor ventilation has been of benefit or detriment.
Mr Waring-Flood had been the engineer who examined the premises on behalf of CSG and was the author of the CSG report dated 26 October 2009 and the letters written by CSG on behalf of the plaintiffs to the Council. In preparing the report for CSG he did not review the foundation plans, but assumed that they were built as per the original site classification. To satisfy himself about the adequacy of the footings, Mr Waring-Flood undertook visual assessment of the surface of the footings and relied on a conversation with the original designer, a Mr Henderson, with whom he worked. It was Mr Waring-Flood's opinion that the footings were performing adequately prior to the planting of the trees. When asked when the trees were planted his answer was:
"Well again I don't know the exact timeline of it."
Mr Waring-Flood gave evidence that the house had performed adequately for a period of over 10 years, which, in his opinion, is the period that most house foundations will have already shown signs of distress if the footings are inadequate due to site reactivity.
As referred to above, Mr Waring-Flood was of the opinion that the broken sewer pipe was responsible for 25% of the damage that occurred to the house. That was based on assumptions that the breakage had occurred between 2007 and 2009. It was assumed to be after 2006 because MPC Consulting Engineers inspected the sub-floor and reported no findings at that time. At the time of his own inspection in 2009, the toilet had been moved and there was no effluent leaking from the pipe. He gave the following evidence in respect of the broken pipe:
"Q: But you can't know Mr Waring-Flood how long it had been leaking for, can you?
A: Not quantifyiably, no.
Q: You don't know what caused the pipe to fracture, correct?
A: If you make it as a statement of fact that is correct but I believe I know what the cause was.
Q: You came to a conclusion that that to was caused by the tree roots, is that right?
A: My first conclusion is that the sewer was broken through reactive clay soil movement and I believe that's unquestioned by all of the people have looked at, professionals. It is a case of determining what the excessive soil moisture movements. That is my opinion. That is the tree roots, yes.
Q: You say the fact that the pipe was fractured because of soil movement is unquestioned by the people who looked at it, is that right?
A: That is what I believe, yes."
It was then put to Mr Waring-Flood:
"Q: Mr Waring-Flood do you tell his Honour that all of those experts went and inspected the pipe to determine the cause of the pipe fracture, and all independently came to the conclusion that that was the cause, and came and told you that, is that your evidence?
A: No, it's clearly not.
Q: Then they don't know, do they?
A: The case with this - this problem is nobody knows."
Mr Waring-Flood was also of the opinion that drainage on the site was a contributing factor to the damage. The process of rainwater causing swelling of the soil on some parts of the site, and then drying out, was, in his opinion, causing damage to the property. When asked about that phenomenon he gave the following evidence:
"A: That phenomenon was likely causing some of the internal cracking I observed by ponding within the internal pad footing depressions."
It was however, a minor concern that different parts of the site might tend to be wetter or dryer simply because of the sloping nature and the presence of the house on it.
Mr Waring-Flood was prepared to preclude the aboveground pool on the neighbouring property on the basis that pools are generally not emptied and refilled on a regular basis and that inundation on the property from such an event he would expect would occur once per year. However, he did not know for how long the pool was there or when it was taken away. His evidence in respect of the pool could only be regarded as speculative.
It was Mr Waring-Flood who recommended the sub-floor ventilation be improved. When asked about his knowledge of the timing of the various wetting and drying cycle of different parts of the site and other factors affecting the site, his evidence was as follows:
"A: My knowledge of the timing at this juncture is very poor, as you can see. My knowledge at the time when I was forming the opinions I believe would have been sound. Once my opinions have been formed through those pieces of evidence I maintain my understanding, and I maintain the knowledge. The timing of events is something that my mind finds difficult to maintain."
With respect to underpinning, as a general proposition, Mr WaringFlood agreed that to underpin one part of the house leaves the rest exposed to damage, because it could move whereas the part underpinned could not. It was put to him then as a general proposition that underpinning part of the house on a highly reactive clay soil site would be bad engineering practice, a proposition he disagreed with. He did, however, say:
"I would say that it's a risky process and it requires an experienced engineer to make a proper assessment."
It was put to him that there had been observed more damage to the house since the underpinning occurred in 2009, to which answered:
"A: We have, but they have prevented the damage from increasing in the severity classification to the rear of the property as -
Q: In your opinion?
A: As observed. As measured.
Q: But whether that's been done by the underpins is your opinion; is that right?
A: Correct.
Q: The additional damage that you've seen since the underpinning is in about the middle of the house; is that right?
A: It is moving through the house, yes, it has been steadily moving from the rear towards the front, in my observation."
In attributing that damage to the suction effect of the tree roots, Mr WaringFlood gave this evidence:
"Q: So the damage to the middle of the house you explain now by the drying effect of the roots extending right through to the middle of the house, even if the roots aren't there; is that right?
A: It is right. I can make an analogy for you, if you like.
Q: Have you conducted any soil moisture testing on any parts of the site?
A: No."
In respect of a survey undertaken by Mr Barker on behalf of the Council which showed certain settlement, Mr Waring-Floor gave the following evidence:
"Q: So if those figures were capable of being interpreted as showing that the area behind the garage and WC is higher now than a year ago, if that's the case, then that could only mean that the area that's supposed to be dried by the trees has in fact swelled where all the rest of the house has dropped, correct?
A: Correct.
Q: Can you think of any explanation for why all the rest of the house would have dropped in the last 12 months?
A: Through tree root drying and natural drying of the sub-floor through the increased ventilation.
Q: Right down to the front of the house?
A: Yes, potentially.
Q: So you say now that you think the effect of these roots might extend right out to the front of the house?
A: It's a potential possibility, but I've been working with minimum suction zones. I understand that Ironbark trees can exert a suction pressure up to four times the height of the tree, whereas I've been working on 1.6 times. Four times the height of the tree would encompass the entire property."
Mr Waring-Flood's response to the rigid grid of footings designed by Mr Barker was that it would be greatly more expensive than the foundations that were designed and built in respect of this house. Finally, it was put to Mr Waring-Flood that he could not be confident that in all of the circumstances roots from the trees at the rear of the property had been responsible for any of the damage to the plaintiffs' house, which he described as "completely incorrect". It was put to him that he chose to ignore multiple possible other causes to which he replied, "That's incorrect".
To complete the evidence on the plaintiffs' case, a view of the premises took place on the morning of Wednesday 12 December 2012. In attendance were counsel and solicitors for both parties, together with Mr Waring-Flood on behalf of the plaintiffs and Mr Barker, consultant engineer, upon whose evidence the defendant relied. Counsel for the plaintiffs pointed out the various defects in the building which comprised the plaintiffs' claim for damages, the general layout of the property and the area behind the plaintiffs' house, abutting Roberts Circuit, being the area the Council planted with trees.
The Defendant's Evidence
Mr Daniel Page is an arborist employed by the Council. He affirmed an affidavit on 17 November 2011 in which he deposed to an inspection he carried out at the plaintiffs' property on 20 November 2009. Mr Page was of the opinion that the soil type in the immediate area of the property was highly reactive clay, which generally resulted in a small root system or "root plate". It was his opinion that the tree roots from trees within the corridor at the rear of the property were not the cause of the damage he observed on the property. In his inspection report drafted on 23 November 2009, he recorded:
"Resident stated that this problem started when new houses were built behind her house, as a result all the water washes through her yard and floods her neighbour's yard in heavy downpours."
In cross-examination Mr Page conceded that at the time of his inspection the trees at the rear of the plaintiffs' property were 8-10 metres high. He acknowledged that trees planted close to houses posed a real risk of causing damage to those houses, but in this case, he did not believe the roots were the cause.
Mr Page identified camphor laurel trees and some species of ficus as problematic trees which were capable of causing damage to houses. Neither were planted here.
It was put to Mr Page that Mrs Holloway did not state the words which appear in paragraph 10 of his affidavit, however, it became clear that he was relying on his report of 23 November 2009 as the basis of the conversation recorded.
Whilst he believed that tree roots were not the cause of damage to the property, Mr Page conceded in cross-examination that he did not know that. He conducted what he referred to as an initial inspection, however, he gave the following evidence:
"Q: Is that the type of damage that occurs when tree roots extract water from sub-soil?
A: I guess so, yes ...
Q: You agree that the type of damage you observed is consistent with tree roots extracting water from sub-soil?
A: No I don't. Not that degree of damage.
Q: Didn't you just agree previously with the proposition that the damage you observed was the type of damage that you could find from tree roots extracting water out of sub-soil?
A: Well you could - not at that site - not that degree of damage.
I then intervened to ask, in clarification of the words "not that degree of damage":
"Q: What was it about the degree of damage that caused you to answer in that fashion?
A: Well there might be some movement, say, in small slabs, they might sink a little bit. But the - the entire house was - back of the house was broken apart like, there were 15mm gaps in the walls. I could not see how the roots from those trees would cause that amount of damage."
Mr Page was then taken to photographs of the tree roots entering the rear of the plaintiffs' premises which were annexed to the report of Mr Ford (pp 112-113 of the plaintiffs' tender bundle). It was then put to him that if roots of that type were in the backyard of the property in 2009 he would expect to see the damage that he had described at the plaintiffs' house, to which he replied "Not that amount of damage". Mr Page was of the opinion that the damage was caused by reactive clay soil expanding and shrinking, and it was put to him that nothing else would explain the shrinkage of the sub-soil and that the damage was consistent with the roots extracting water from the sub-soil, to which he replied:
"I believed it was from the clay expanding from the moisture."
He then gave this evidence:
"Q: You say in your report of 2009 that it's from expanding and shrinking, correct?
A: Yeah.
Q: The shrinking I put to you is caused by the roots, correct?
A: Yes.
In respect of his description in his affidavit of the eucalyptus trees having a small root plate, he gave the following evidence:
"Q: If you accept that the roots in photograph 19 and photographs 17 and 18 are from the trees in the nature strip and they're at the back of the plaintiffs' house, you couldn't say that the trees in the nature strip, the subject of these proceedings, had a small root plate, could you?
A: No."
Mr Lindsay Field was employed as the City Arborist with the Council since 19 April 2010. He swore an affidavit on 17 November 2011. He had previously worked in various tree management roles for a number of Councils. On 29 March 2011 he attended at the plaintiffs' home to carry out an examination of the site. He described the planting of trees in the corridor at the rear of the premises as a native mix of trees including Sydney blue gum trees, grey Gum trees, ironbark trees and a number of smaller shrub species including Melaleuca and Callistemon. Council staff excavated a number of holes along the southern fence line of the property in his presence to enable him to examine the existence of tree roots emerging from the Council land onto the plaintiffs' property. The first hole established one tree root 40mm in diameter at a depth of 5cm below surface level. A second hole revealed only a number of fine roots up to 1.5mm in diameter. Further excavation revealed no further evidence of roots and a number of photographs were taken.
Based on his investigation, Mr Field was of the opinion that only a small number of roots from the Council's land had passed under the fence onto the rear of the plaintiffs' property. He also observed the topography of the Council land to direct water to the trees and shrubs within it during periods of heavy rain. An aerial photograph of the property taken in 2008 ("LF7") showed the land to the rear of the plaintiffs' property was higher above sea level than the property itself. It was Mr Field's opinion that the direct physical extraction of water from directly under the dwelling at the property by the roots of trees or shrubs within the Council land would be minimal.
In cross-examination Mr Field said he observed the trees behind the plaintiffs' property were 18 metres in height, but not as yet fully grown. He disagreed with the proposition that, given the heights of the trees and the size of the canopy, the roots of the trees would be extracting a substantial amount of water out of the sub-soil of the plaintiffs' property. He did concede, however, that he would need to know the conditions over a period of time before assessing whether or not water was withdrawn from the property.
Mr Field did agree with a proposition based on the publication issued by the CSIRO that trees that were going to grow 20 metres tall would need to be 15 metres away from the plaintiffs' house, and that four trees within the relevant planting were within 15 metres of the house. Mr Field was of the opinion that given the high clay content of the reactive soil, the root system would remain shallow.
The defendant relied on Mr Robert Barker, Chartered Professional Engineer, who prepared two reports dated 23 November 2011 and 16 November 2012. He inspected the property on 29 March 2011 for the purpose of determining the causes of the damage that he observed to the residence on that occasion. He had access to numerous documents providing background material including the affidavits of Mr Holloway affirmed on 22 September 2011 and 6 November 2011 and the affidavit of Mr Sharman sworn on 9 November 2011.
Table 3 of Mr Barker's report dated 23 November 2011 (p 119 of defendant's tender bundle) set out a convenient summary of the damage he observed in the various parts of the plaintiffs' home and the exterior of the premises. There is no doubt that it was extensive, as observed by me during the view that took place of the premises and referred to in paragraph 70 above.
At paragraph 11 of his report (p 125 of defendant's tender bundle) Mr Barker sets out his opinion as to the cause of the extensive damage. Paragraphs 11.1 to 11.8 concern Mr Barker's opinion as to the deficiencies in the footings supporting the house. At 11.9 he states:
"The pattern of damage consistent with the subsidence of the internal sub-floor pad footings with respect to the external strip footings was evident in the residence."
The remedial work carried out by underpinning the rear wall of the premises, together with improvement of the sub-floor ventilation, in Mr Barker's opinion, had the following impact:
"11.11 ... the combination of supporting the rear walls while increasing the drying effects of the sub-floor area has resulted in the observed damage pattern that was consistent with the settlement of the internal floor with respect to the external walls."
Mr Barker referred to a survey taken on 29 March 2011 at paragraph 11.14:
"The survey indicates that the rear of the residence has subsided 50mm with respect to the front western corner, however, the front eastern corner has also subsided at 18mm with respect to the front western corner. That is, there is an 18mm slope across the front of the residence. Similarly, there is a 22mm fall from the front eastern corner to the rear eastern corner. Finally, there is a 10mm fall from the rear eastern corner to the rear western corner. All of these movements are within 50mm of calculated reactive movement that could be expected to occur on the site."
Mr Barker was of the opinion that the change in levels was indicative of reactive soil induced shrinkage as a result of the normal drying of soils on the site. He set out his critical findings as follows:
"11.18 In my opinion the initial damage to the Property reported in 2006 was substantially caused by localised drying shrinkage of reactive soils. The reduction in the magnitude of the damage to the external masonry walls is attributed to a recovery of the foundation soil moisture levels and a subsequent swelling of the effected soil profile around the exterior of the property, as evidenced by the reduction in magnitude of previously reported damage.
11.19 In my opinion the damage observed in the interior of the property at the time of the inspection on 29 March 2011 was substantially caused by inappropriate remedial works (limited underpinning and increased ventilation of the sub-floor area) that was intended by CSG Engineers to address a combination of opposing influences on the reactive foundation soils on the site (wetting effects and storm water runoff inundation, sub-surface seepage, broken sewer drain [by ventilation] and the drying effects from nearby trees [by underpinning]). The subsidence of floor and internal walls of the residence may be attributed to the drying of the sub-floor area following the increase in the sub-floor ventilation. Therefore, two mechanisms have been concurrently causing swelling of the external swell profile and shrinkage of the soil profile beneath the interior of the residence, resulting in the observed pattern of damage. ...
11.22 Further, it is my opinion, that the magnitude of the damage to the rear of the residence may be in part attributed to deficiencies in the original design of the strip footings, which may have been shown to have been inadequately detailed for the wall layout of the residence and ignored the requirements for transverse internal strip footings to extend from re-entrant corners as specified in AS 2870.1-1988. Additionally, the "deem to comply" strip footings specified in AS 2870.1-1988 were, following publication of the standard, found to be inadequate and have been upgraded in AS 2870-1996 to provide greater stiffness and resistance to shrinking and swelling reactive soil movements."
In respect of the question whether trees planted on Council land were causing the damage complained of, he set out his opinion as follows:
"14.9 Observations made during the inspection of the Property on 29 March 2011 indicate there has been recovery of previously recorded damage in 2006 and hence the reactive (up and down) movements continue to be operating on the site rather than purely shrinkage (down) movements which would be expected with the impact of trees.
14.10 Based on my analysis of the site and the observed and recorded movements, there has been no net tree root induced subsidence movement of the Property since 2006 and certainly since 2009 when underpinning was undertaken. The damage that is currently manifested is non-repaired pre-2006 damage and subsequent damage that is the result of the changed ventilation regime to the sub-floor area.
14.11 The drying effects from trees are a known factor in the cause of movement of reactive soil profiles. However, given:
(i) The absence of any soil or moisture profile evidence that could relate to the foundation soil movements and footing/structure responses, to the drying effects of approximate trees;
(ii) That the pattern of movement measured within the entire property is indicative of reactive soil movement, and
(iii) The magnitude of recorded movement is within the range of expected movement for a Class H site.
In my opinion, none of the observed damage can be specifically attributed to the effect of trees located in the public reserve to the south of the property."
The purpose of Mr Barker's second report dated 16 November 2012 was to respond to the plaintiffs' further expert evidence, being the report of AWL Engineering Pty Limited dated 26 September 2012, and the affidavits of Mr Sharman sworn 20 September 2012 and Mr Ford sworn 25 September 2012.
In that report, Mr Barker provides an opinion that it was incorrect to suggest that the footings for the property were adequately proportioned or designed. A fair summary of Mr Barker's opinions is that he takes issue with most of Waring-Flood's opinions as to the cause of the damage, and the effect of the rectification works, and does not agree with the costings provided by Mr Sharman as to both rectification work undertaken and to be undertaken.
In respect of the broken sewer pipe, Mr Barker stated that there was no evidence that flexible connections had been provided at the time of construction for waste drains and that the use of rigid connections in pipe work between in ground trenches and a house structure are a recognised cause of damage to drainage pipe work on reactive clay sites.
In response to Mr Waring-Flood's opinion that reactive clay movements had occurred which were greater than expected because of shrinkage caused by trees, Mr Barker states at paragraph 9.7 of his report:
"Mr Waring-Flood has not provided any evidence of the magnitude of any movement in the residence, at any point in time, that would enable a comparison to be made with the expected range of movement to which the residence could be subjected. The survey of the residence undertaken by Barker Harle on 29 March 2011 and shown in drawing 10001/3 indicated that 50mm differential movement experienced by the residence was within the accepted range of 40mm to 70mm for a class H site."
Mr Barker went on to dispute Mr Waring-Flood's opinion that the footings were adequately proportioned and designed to accommodate seasonal movement, and that tree root suction was the principal cause of damage by causing extreme drying shrinkage followed by extreme swelling and then in turn extreme shrinkage of the foundation soil. In Mr Barker's opinion the strip footings of the residence, as approved by Mr Henderson, did not meet the "deemed to satisfy" provisions of AS2870 - 1988. In order to satisfy that standard, the footings were to have:
"(a) Internal footings extending from all re-entrant corners to continue to the opposite external footings;
(b) Internal footings shall be of the same proportions as the external footings and run from external footing to external footing;
(c) Internal pads are not permitted. Internal support shall be provided only by internal strip footings or piles. The distance from the external footing to the first internal pile shall not be less than 2.5 metres and other piles are to be arranged to suit the floor system support system but spacing shall not exceed 3 metres;
(d) Internal footings can be used for the complete support of the floor;
(e) Construction details are to comply with revisions of Clause 6.2 and Clause 6.3;
(f) Clause 6.3 (see in brackets) requires that water runoff shall be collected and channelled away from the house." (See paragraph 9.9 of his report)
Mr Barker commented that the certification of the footings made by Mr Henderson did not make any reference to the design being prepared by engineering principles, but rather simply noted that they were "structurally adequate".
A separate notation advising "footings designed to be safe, serviceable and repairable as per Mine Subsidence Guidelines for 5.00 metres pothole design" did not make any reference to the design of the footings being for a class H site reactivity or otherwise acknowledge the requirements of AS 2870 - 1988 (see paragraph 9.11 of his report).
Mr Barker was of the opinion that the footings failed to meet the "deemed to satisfy" provisions in that:
"(a) Strip footings were not provided under all masonry walls;
(b) Internal footings did not extend from re-entry corners through to opposite external footings;
(c) Pad footings were provided when they were not a permissible footing type. Piles, found at 2 metres below surface level were a permissible form of isolated internal footings;
(d) The spacing of the internal line of support of the floor framework on isolated footings at approximately 3.5 metres exceeded the maximum spacing of 3 metres from the external strip footing to the internal line of support;
(e) The external isolated pads along the western side of the carport satisfied neither the requirements of the MSB pothole design nor AS 2870."
In respect of the underpinning work that had been carried out by way of rectification, Mr Barker stated at paragraph 9.25:
"The effect that underpinning has on localised areas of a structure has been discussed above, the interaction between an unpinned area and an unsupported area portion of a structure has also been discussed above. The result is that the building is continuing to move as moisture in the soil profile changes, which it will do continuously and seasonally and the cause and magnitude of damage at any particular location needs to be carefully measured and monitored to be able to provide an opinion, with any certainty, as to the cause of the movement."
No such measurements of any kind had been undertaken so as to express a reliable opinion. Mr Barker stated at 9.26:
"I was unable to explain the presence of some of the observed damage and movement observed during my inspection on 29 March 2011. A single data set is insufficient to provide evidence of rates or direction of movement."
He went on to say at paragraph 9.29:
"9.29 Mr Waring-Flood has not provided an explanation for the eastern side of the residence being lower then the western upslope side. In my opinion, it is a normal phenomenon on reactive soil sites for the down slope side of the residence to become lower than the upslope side, as the soil profile on the upslope side is periodically replenished by stormwater runoff and the soil profile on down slope side becomes dryer and shrinks, as the stormwater runoff drains away."
In respect of Mr Ford's opinion that tree roots had penetrated the footings or foundations of the property, Mr Barker gave the following evidence:
"(a) From my reading of Mr Ford's affidavit, he didn't provide any evidence as to how he formed that opinion. And based on the photographs that he attached in connection with his comments, the photographs that he indicated were confirming his view were of roots that were at the top of the footing and penetrating the subfloor brickwork and there was no evidence they were beneath the footings or in the foundation, the subfloor area of the house. So my view was that I couldn't see how he could support his view based on that information."
Mr Barker was cross-examined on the basis of the certification of the approved building plans (exhibit A) by the Mine Subsidence Board. The effect of his evidence was that the certification involved the Mine Subsidence Board rubber stamping the approved plans on the basis of engineering certification on the footings stating that they were structurally adequate. In this case, that certification was provided by Mr Henderson. Mr Barker disagreed with the proposition that the footings had been designed to engineering principle in accordance with AS 2870. That was the relevant standard at the time of construction.
Mr Barker was also cross-examined in relation to exhibit C, the CSIRO Australia Information Service Sheet in respect of the planting of trees in proximity to swellings. Mr Barker did not disagree with the general proposition contained in that document to the extent that if trees were to grow to a height of 20-30 metres, they should not be planted within 20-30 metres of a dwelling.
Mr Barker was asked about tree root induced subsidence on the site prior to 2006 and it was put to him that tree root induced subsidence did occur prior to 2006, to which he answered:
"A: I don't know what causes subsidence prior to 2006."
He was then asked:
"Q: Well, if you say that there's been no net movements since 2000 and - tree induced subsidence movement since 2006, it's the case that there was tree root subsidence prior to 2006. Isn't that the case?
It was only three years later in 2009 when CSG were employed to investigate the matter that roots from the trees planted on the adjoining property were identified as a contributing factor, combined with the alteration of the drainage to the property. CSG went on to recommend and design the repairs to the foundations of the property by way of underpinning.
From October 2009 Mr Waring-Flood became an advocate for the plaintiffs. He was the author of the report referred to in paragraph 24 above, being Exhibit J to his affidavit. In that letter he wrote that:
"The principal cause of the previous damage and more importantly the ongoing damage is due to the presence of large trees in the Council reserve at the rear of the property ..."
Mr Waring-Flood had no proof for that contention. The photographic evidence referred to in paras 77 and 79 above demonstrated the root encroachment to be minimal. He had carried out no measurements nor soil profile assessments. Geo-technical engineers, namely, Douglas Partners, had not found that to be the case. The underlying contention that it was the evaporation of water from the sub-soil under the house caused by tree roots could only be regarded as theoretical and somewhat speculative. It ignored wetting influences, which have been referred to above, namely, run-off from the neighbour's pool, the broken sewer pipe which flowed for an indefinite period of time and stormwater runoff. Drainage to the rear of the site was clearly a problem according to both Mr and Mrs Holloway. It also ignored the slope of the land and the soil profile and the existence of loose foundation material. In addition was a problem identified with the ventilation with the sub-floor area recommended by CSG and eventually carried out by Mr Holloway sometime after the underpinning work was completed.
Mr Waring-Flood also accepted Mr Henderson's word on the structural adequacy of the footings without independently assessing that question. He conceded that underpinning the rear of the house left the rest of the house exposed to further damage. It was described as a "risky process that required expert engineering to make a proper assessment".
Whilst the damage to the property had, up until 2006, been exhibited to the rear of the property, following the underpinning work, the damage from 2010 thereafter occurred in the middle of the house. I am satisfied on the evidence that that flowed directly from the underpinning work which fixed the rear of the property but allowed the middle of the house to flex. It was therefore the underpinning work which caused the subsequent damage.
In the authorities referred to by Preston CJ in Robson outlined in paragraph 113 above, where it was established that roots encroaching on to a neighbour's property extracted moisture from the ground causing shrinkage of the soil and thereby undermining foundations and/or causing damage, such encroachment was the only or principal cause of such damage. Here, there are a multitude of alternative explanations and potential causes for the damage.
I prefer the evidence of Mr Barker over that of Mr Waring-Flood as to the cause of the subsidence of the house and the damage thereby exhibited in the house. I am mindful that Mr Barker inspected the property on 20 March 2011, however, I accept his opinion at paragraph 85 above, that the pattern of damage was consistent with the subsidence of the internal sub-floor pad footings with respect to the external strip footings. I also accept his opinion that the underpinning of the rear wall of the premises, together with improvement in the sub-floor ventilation resulted in the observed damage pattern which was consistent with settlement of the internal floor with respect to the external walls. Further, the survey carried out on 29 March 2011 (as outlined is paragraph 87 above) I accept was indicative of reactive soil induced shrinkage as a result of the normal drying of soils as set out by Mr Barker. I therefore accept his opinion set out in paragraph 88 above that the initial damage to the property was substantially caused by localised drying shrinkage of reactive soils and that there was recovery from time to time of the foundation soil moisture levels and subsequent swelling of the affected soil profile around the exterior of the property. I am not satisfied that the encroachment of tree roots on to the property such as was established by the plaintiffs was causative of the shrinking of the reactive soils.
I further accept Mr Barker's opinion that the damage observed on inspection on 29 March 2011 was substantially caused by inappropriate remedial works, namely, limited underpinning and increased ventilation of the sub-floor area and not by the encroachment of tree roots.
Mr Barker candidly said that he was unable to identify the causes of subsidence prior to 2006. He did not know what caused the drying shrinkage of reactive soils in 2006 which caused the damage.
I find that the damage was caused by movement of the house on its footings caused by shrinking and expansion of the reactive soil profile under the house. I am not satisfied on the balance of probabilities that that damage prior to 2006 was caused by the encroachment of tree roots, however, I am satisfied that following the repair work carried out in 2009 it was not caused by encroachment of tree roots but was caused by the underpinning work carried out by Mr Sharman on behalf of the plaintiffs.
That finding means that the plaintiffs have not discharged the onus of proof on them and must therefore fail. It does not involve a positive finding of what did cause the damage in question. A great deal of debate took place between the experts as to whether the footings, which were approved by both the Council and the MSB, and certified by Mr Henderson who was employed by CSG, were adequate for the site. The certification that I have referred to noted that the footings were "structurally adequate". However, although it is unnecessary for me to do so, I prefer Mr Barker's evidence in respect of the strip footings to that of Mr Waring-Flood. I accept therefore Mr Barker's opinion that the footings failed to meet the "deemed to satisfy" provisions of the relevant standard as set out in paragraph 97 - 99 above. I accept Mr Barker's opinion set out in paragraph 104 above that the impact of the tree roots on the building were not a factor prior to 2006 although he conceded in cross-examination that "they're a possibility". That is not sufficient in my view for the plaintiffs to discharge the onus of proof in this case on the balance of probabilities that it was the encroachment of tree roots which caused the pre-2006 damage, given the inadequacy of the footings identified by Mr Barker and other factors outlined above.
Conclusion
For the above reasons, I am not satisfied that the plaintiffs have proved on the balance of probabilities that the damage to their home was caused by the encroachment of roots from trees planted by the Council on the adjacent property in 1997. The way the plaintiffs' case has been pleaded, Council could only be liable once they became aware of the nuisance in October 2009. However, based on the findings I have made above, whilst Council was thereafter aware of damage to the plaintiffs' property, the plaintiffs' have failed to establish that that damage was caused by the encroachment of tree roots. I therefore find that there was no actionable nuisance on the plaintiffs' property and the Council is not liable for the damage.
The further issues listed in paragraph 13 above therefore fall away. There is no question to be determined in respect of apportionable claims between concurrent tortfeasors. Given the findings that I have made, there is no utility in assessing damages, as even if I am wrong in those findings the encroachment of tree roots could only have contributed to damage prior to 2009, in a minimal way, at a time when the Council were not on notice and therefore not liable.
Orders
I order as follows:
(1) Verdict for the Defendant.
(2) Plaintiffs to pay the Defendant's costs.
(3) Exhibits to be returned.
(4) Parties to have liberty to apply on seven days notice for a special costs order if required.
(5) File to be returned to the Newcastle District Court Registry within 28 days in the absence of any application for a special costs order.
Decision last updated: 16 May 2013
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