Kent v Aquilina [2025] NSWLEC 1160 | Case summary | Zoe

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Kent v Aquilina

[2025] NSWLEC 1160

Land and Environment Court (NSW)|2025-03-18|Before: Douglas AC

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Court

Land and Environment Court (NSW)

Decision date

2025-03-18

Before

Douglas AC

Catchwords

TREES (DISPUTES BETWEEN NEIGHBOURS) –damage to brick fence and
retaining wall –apprehension of injury

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Catchwords

TREES (DISPUTES BETWEEN NEIGHBOURS) –damage to brick fence andretaining wall –apprehension of injury

Judgment

Source: NSW Caselaw (www.caselaw.nsw.gov.au). Converted to plain text by ZoeLaw. Not the official version.

Medium Neutral Citation: Kent v Aquilina [2025] NSWLEC 1160

Hearing dates: 4 November 2024

Date of orders: 18 March 2025

Decision date: 18 March 2025

Jurisdiction: Class 2

Before: Douglas AC

Decision: The Court orders that:
(1) Orders are at [249].

Catchwords: TREES (DISPUTES BETWEEN NEIGHBOURS) –damage to brick fence and retaining wall –apprehension of injury

Legislation Cited: Dividing Fences Act 1991, s 3
Environmental Planning and Assessment Act 1979
Limitation Act 1969
Trees (Disputes Between Neighbours) Act 2006, Pt 2, 4, 7, 8, 9,10,12
Uniform Civil Procedures Rules 2005, Sch 7

Cases Cited: Baker v Grabovac [2010] NSWLEC 1289
Barker v Kyriakides [2007] NSWLEC 292
Fang v Li [2017] NSWLEC 1503
Robson v Leischke (2008) 72 NSWLR 98
Stevens v Russell [2016] NSWLEC 1233
Yang v Scerri [2007] NSWLEC 592

Texts Cited: AS4970:2009, Protection of trees on development sites 2009
Woollahra Council Tree Preservation Order 2006

Category: Principal judgment

Parties: Richard Kent (Applicant)
Nellie Aquilina (Respondent)

Representation: Counsel: R Kent (Self-represented) (Applicant) A Hannam (Respondent) Solicitors: FW Ewart and Ewart Solicitors

COMMISSIONER: An old brick fence above a brick retaining wall (the wall) separated the rear yards of neighbouring semi-detached properties in Woollahra. The age of the dwellings was estimated at about 100 years.
In her affidavit of 15 October 2024 (Exhibit 1), Nellie Aquilina (the respondent) noted the parties’ properties were originally under a single title, which was subdivided by the installation of a common east-west dividing wall in November 1956. Exhibit 1, Annexure B2 was a copy of the cancelled original title, dated 9 May 1957.
The respondent’s mother purchased the south side property in 1957. The property then passed through a chain of succession until Mrs Aquilina inherited part ownership in or around 2009, before she became the sole owner of the property in March 2012.
Mrs Aquilina submitted two surveys from North Western Surveys Pty Limited, from December 2010 (Annexure F6 of Exhibit 1), and October 2024 (Exhibit 3). The 2024 surveyor identified the applicant’s property as Lot A and the respondent’s property as Lot B, per the title documents. I will maintain this identification of the properties.
The applicant is Richard Kent, an owner of Lot A.
In Exhibit 3, at p 2, par 2, the 2024 surveyor said the “wall did not exist” in the title diagram dated December 1956 … “and instead an old fence existed along the entirety of the subject boundary suggesting that ground level difference between Lot A and B was minimal in 1956”. Mrs Aquilina resided at Lot B until 1961. In Exhibit 1, par 5, Mrs Aquilina said she did “not know precisely when the dividing wall was constructed”.
Exhibit 3, at p 1, par 8 noted, “It appears that the wall is retaining lot B, as lot B is up to approximately 0.9m higher than lot A.” The common boundary extended approximately east-west from the front to the rear of the dwelling, then deflected slightly north. The wall straddled the boundary where it met the party wall of the dwellings but extended towards the rear boundary slightly south of the surveyed common boundary. The wall then appeared to intersect the rear boundary at a perpendicular angle.
Consequently, the vast majority of the wall was within the respondent’s land such that the wall was increasingly distant from the common boundary as it extended westward, towards its intersection with the rear boundary. The age of a brick wall along the rear boundary was not considered in Mrs Aquilina’s documents, but the two walls were previously joined.
Annexure E of Exhibit 1 was a chronological list of 62 items of correspondence spanning 2005 to 2017, between Mr and Mrs Kent, Mrs Aquilina, FW Ewart & Ewart (the respondent’s Solicitor), Mr JJ Davies (a former part owner of Lot B), and Woollahra Council (Council). However, the list did not detail the purpose or content of correspondence.
Before or during 2008, Mr Kent detected a lateral crack running along the wall about 900mm above his ground level, which was the approximate ground level of the respondent’s land.
On 29 September 2008, Mr and Mrs Kent wrote a letter to Council titled, “Re: Retaining wall collapsing” (Exhibit D). The letter said, “[m]y neighbours wall looks not in good condition as the tree appears to have moved it off the foundation and a crack in the wall has appeared. Can someone come and inspect it?”.
In Exhibit 1, at pars 12-16, Mrs Aquilina said her brothers, Richard and Albert, were each admitted to hospital and full-time care prior to Richard’s death in March 2009. Though Mrs Aquilina did not specify when the property was vacated by Richard or Albert, it was reasonable to assume it occurred prior to 2010. The property had remained vacant ever since.
The site diagram in the applicant’s Tree Dispute Claim Details (Exhibit B), displayed a Frangipani tree, labelled T2, located in the north-western corner of the respondent’s back yard, near the intersection of the wall and the rear boundary wall.
In a Notice of Determination of a Tree Preservation Order Application (Exhibit M), dated 30 July 2010, Council granted permission for removal of the Frangipani tree from the respondent’s rear garden. Mr Kent said the Frangipani tree was removed during 2010.
On 28 October 2010, Council issued Mr JJ Davies, an ‘Order to repair boundary wall’ (Exhibit C), “[u]nder the guidance and supervision of a practicing structural engineer”. “Reason/s for the Order” were, “[t]he wall in its current state shows signs of cracking and dislodgement of the masonry components” and “[t]he wall appears dilapidated as to be prejudicial to occupants of the subject property…”
The Order required compliance within 90 days, but the respondent failed to undertake the wall repairs. At the hearing, Ms Kallas (one of Mrs Aquilina’s daughters) contended that Council failed to enforce the Order.
On 8 November 2010, Mrs Aquilina received a report from Mr Simone of Siga Structural Engineering, based on a wall inspection undertaken on 30 October 2010 (Exhibit L / Siga report). The purpose of the inspection was, “[r]espond to Council’s correspondence dated 2 August 2010, a proposed order”.
Siga reported “a brickwork wall approximately 5.6m long which is 2.0m high at the residence and steps to approximately 1.1m above the ground level along the Northern boundary” and, “[t]he boundary wall appears to be of single skin brickwork construction … on a 900mm high brickwork retaining wall”. The report noted a 10-15mm gap between the wall and the respondent’s residence.
“Recommended Actions” included to, “[c]onsider what remedial works you would like to do e.g. renew concrete paving and/or boundary fence as well as reconstruct the boundary retaining wall.” The summary said, “the retaining wall does not appear to pose an immediate danger, however, it and the single skin fence should be upgraded (within the next six months) to suitable relevant standards”.
Nonetheless, no wall works were undertaken by Mrs Aquilina.
n a timeline at question 32 of Exhibit B, Mr Kent claimed to have emailed a fencing notice to the respondent in August 2016 and “offered to pay half of the dividing wall”. Mr Kent said he emailed “[d]etailed costs and design by my own estimates”, but Nellie Aquilina “requested detailed quotes which I told her I was unable to obtain. Suggested they get quotes”.
Mr Kent claimed Melissa Kallas, in an email dated 15 December 2017, said “a builder sited the job and a structural engineer’s report needs to be obtained before we can proceed to quotations”. According to Mr Kent, “no further action was taken”.
The timeline in Exhibit B noted that, after observing further movement in the wall, Mr Kent obtained a structural engineer’s report in May 2022 which said, “hydrological pressure on the wall is causing the problem”. Mr Kent allegedly “sent a formal fencing notice” to the respondent in July 2022, “requesting repair of wall”. On 24 August 2022, as six weeks had elapsed with no reply, Council sent the respondent a fencing notice and “an engineer’s report and quote”, on Mr Kent’s behalf.
On 5 February 2023, Council issued the respondent a Development Control Order (Exhibit J), “to repair side masonry boundary wall” within 90 days of the Order. The terms of the Order were identical to the Order of 2010, except the second ‘Reason for the Order’ was altered to, “[t]he masonry boundary wall is so dilapidated as to be prejudicial to occupants of the subject property…” (emphasis added).
The respondent failed to comply with the 2023 Order to repair the wall.
Mr Kent noted receiving a recommendation on 26 May 2023, from Council’s Manager Legal, Compliance and Enforcement, to attempt to resolve the issue in the Land and Environment Court (LEC), given his belief that trees were, “the cause of the movement of the wall”.
Consequently, Mr Kent made an application on 27 June 2024, pursuant to s 7 of Pt 2 of the Trees (Disputes between Neighbours) Act 2006 (the Trees Act), based on his claim that one of the respondent’s trees had caused damage to the wall in the past, and that one tree was currently causing wall damage and was likely to cause wall damage in the near future. The application also included a claim of risk of personal injury from the existing tree and the wall.
Photographs from 14 January 2024, at pp 14, 15, and 17 of an Arboricultural report by Arbor Express (Exhibit E), displayed a Ce**ltis sinensis (Hackberry tree), growing close to the wall on the respondent’s land.
Mr Kent submitted a letter from Council Tree Management, dated 15 August 2024, that noted the Hackberry was “approximately 8m in height” and its removal did not require Council permission.
Annexure A of Exhibit 1 displayed a photograph from 24 August 2024, which showed the Hackberry tree, lopped to 1.5-2 m in height.

The Frangipani tree caused movement in the base of the western end of the dividing brick wall which in turn led to a crack running along the length of the wall. This resulted in potential damage to Mr Kent’s rear deck, should the wall collapse due to the full-length crack.
The respondent undertook no maintenance over 15 years while her property had been vacant (2010-2024). A self-sown Hackberry tree that grew behind the centre of the dividing fence placed further pressure on the wall and caused the crack to grow significantly wider. In late 2023, the top 2m tall fence section tipped southward to now rest against the Hackberry tree. Subsequently, vertical cracks developed in the wall. Consequently, the lower brick retaining wall and the upper brick fence are at risk of collapsing at any time.
Factors other than the tree contributing to damage: In 2023, an Engineer indicated that Hydrological [sic] (Hydrostatic) pressure may also be an influence due to rusting and failure of the gutter at the rear of the respondent’s dwelling.
Steps by respondent to rectify damage: In 2010, respondent removed the Frangipani tree. The respondent’s engineer (Siga) recommended repair of the wall within 6 months. In 2017, the respondent’s daughter, Melissa Kallas, claimed a builder had inspected the site and she was waiting on a structural engineer, but no works transpired.
Steps by applicant to rectify damage: Repeated contact with the respondent. Orders from Council for wall repair/reconstruction in 2010 and 2023. Mr Kent erected drainpipe to drain away water from respondent’s dilapidated roof gutter. He also sent the respondent two fencing notices.
Factors other than the tree contributing to injury: Surplus stormwater from roof gutter failure results in increased hydrostatic pressure behind the wall, making wall failure more likely.
Furthermore, there is a risk of injury from wall collapse to people below the deck and people on the deck as a consequence of the weakening of brick piers supporting the deck.
Dr Amin of Acroyali Engineering considered the wall structurally unsafe. He advised wall repair/reconstruction should start immediately, or else employ a builder to temporarily prop the wall. As the wall is resting on the tree, tree removal will cause collapse of the dividing wall.
Mr Kent claimed $66,684.40 compensation, based on the cheapest of two quotes from Aurify Constructions (Exhibit F) and DT Asset Management Pty Limited (Exhibit G). The scope of works included tree removal, wall demolition and reconstruction, repair of the respondent’s rear gutter, and removal and rectification of two of the applicant’s deck pillars, and part of the deck. The applicant submitted that removal of the two deck pillars and part of the deck was necessary for builders to gain unimpeded access for the works.
Mr Kent submitted that Council had no record of a development application for construction of the wall and the wall was constructed “without proper authorisation and perhaps (without) compliance with building standards”. Mr Kent claimed that the respondent’s mother was probably responsible for this oversight.
Mr Kent contended he should pay $3000.00, being approximately 50% of the cost of the wall’s fence component, based on his “cheapest quote”.

The respondent’s primary position was that the Court would not find on the balance of probabilities that the damage to the dividing wall, any other property damage alleged by the applicant, or risk of injury to a person, is a consequence of the respondent’s Hackberry tree.
Therefore, the application would be dismissed, and any arrangement between the parties for removal of the Hackberry tree and restoration of the wall would be resolved outside of the proceedings.
If, however, the Court found on the balance of probabilities that damage to property or risk of injury was caused by the Hackberry tree, then the Court should make the ‘Respondent’s Revised Orders’.
If the Court found that the Hackberry tree was one cause of property damage or likelihood of injury, the relative contribution of the tree to such damage and or risk of injury would be reflected in the Court’s discretion to make remedial orders under s 9(1), consistent with inclusion of mandatory matters requiring consideration under s 12(h) and subs (i) of the Trees Act.
Response to the applicant’s evidence: Mr Hannam contended that, consequent to the lack of evidence before the Court that Mr DeJong is qualified in structural engineering, Mr DeJong may not opine “on actual or potential damage to the applicant’s property” and Mr DeJong’s “report is of no assistance in the resolution of this enquiry”.
Regarding the applicant’s engineering evidence in Exhibit H, the Hackberry tree is one causative factor to the wall damage. Other causes were the structural inadequacy of the wall and inadequacies in drainage and stormwater systems on the respondent’s property. Dr Amin refers to the 2010 Siga Engineering report, wherein horizontal cracking and rotation of the wall was already present, but photos in the Siga report showed the Hackberry tree was then not present on the respondent’s land. Yet cracking and rotation had already emerged and have worsened over time.
That cracking and rotation of the wall have worsened over time is unsurprising given the age of the wall, which Dr Amin said was built around the 1930s, and its structural inadequacy with regard to modern building codes.
Among the “lateral loads” said to have contributed to the present condition of the boundary wall, Dr Amin made no reference to structures erected by the applicant, comprising a wooden lattice and metal rods connecting the rear deck on the respondent’s property to the boundary wall, which have also contributed to the failure of the wall. The structures were noted in Mr Prasad’s engineering report (Exhibit 2).
It is unclear to the respondent why those structures do not appear in Figure 1 of Dr Amin’s report as there is evidence before the Court of the presence of those structures up until late September 2024, when they were removed by the applicant.
Mr Prasad observed that some timber on the applicant’s rear deck appeared to have been recently cut.

Various jurisdictional questions raised in the ‘Respondent’s written outline of submissions’ shall be addressed in the following paragraphs, at [66]-[85].
I accept the contention, at par 4 of the Respondent’s submissions, that initiation of action in negligence is not within the Court’s jurisdiction, and that action in nuisance falls outside the jurisdiction of the Trees Act. Nonetheless, I detected no intention by Mr Kent (in Exhibit B) to commence action under negligence or nuisance, or to integrate either into these proceedings under the Trees Act. Discussion regarding negligence or nuisance instead related to the toll the protracted dispute had allegedly placed on the applicant’s family, and appeared to form part of Mr Kent’s substantiation of his claim for relief from equal liability for the cost of wall reconstruction. Nonetheless, there is no remedy available under the Trees Act which provides for compensation for stress, pain and suffering, loss of amenity, and the like.
I accept that the GIPA documents and claims of harassment or unconscionable conduct are irrelevant and they have been set aside. Regrettably but unsurprisingly, protracted tree disputes may escalate to conflict or rash conduct. Details of such conflict are of no interest to the Court except where relevant, at s 10(1)(a), to the requirement of the applicant to make a reasonable effort to reach agreement.
Evidence that serves no apparent purpose other than to cast aspersions on the other party is also set aside. This applied to Annexures F2-F5 of Exhibit 1. Other than perhaps implying that the respondent valued Mr Simone’s opinion, supplementary reports from Siga Structural Engineering about interior and roofing issues from May 2011 (Annexure F2) and March 2012 (Annexure F3) were not relevant. Similarly, I saw no relevance in a plastering report from November 2013 (Annexure F4) and a non-itemised roofing invoice from September 2014 (Annexure F5).
Mr Hannam’s list of the applicant’s evidence, at par 12, was not exhaustive. As an example, the list failed to include Council’s ‘Order to repair boundary wall’ from 2010 (Exhibit C).
Mr Hannam contended that the lack of evidence before the Court that Mr DeJong is qualified in structural engineering, meant Mr DeJong may not opine “on actual or potential damage to the applicant’s property”. I understood this to reference damage to the parties’ common dividing wall.
I am persuaded by Mr Hannam’s submission, only in part. I accept that Mr DeJong’s opinion is invalid and inappropriate when applied to the strength and or adequacy of structures, especially where quantitative assessment or complex calculations were required, or to determination of compliance of structures to the National Construction Code or other standards, or to drafting of construction specifications, and the like.
I do not agree with the respondent, however, with respect to opinions arising from the interaction between trees and structures such as walls and foundations. In this domain, expert arborists regularly assist the Court, in relation to claims of damage to structures by tree roots under the Trees Act, or to management of trees on development sites, under the Environmental Planning and Assessment Act 1979 (EP&A Act).
Expert arborists such as Mr DeJong may reasonably offer opinions synthesised from visual assessment of a tree’s species, age class, size, health, and vigour. Such arborists generally have the benefit of familiarity with characteristics of different species, in terms of likely growth rates of trunks and roots, and of species renowned for causing extensive damage to structures. Based on their understanding of typical and species-specific distribution patterns, structure, morphology, and functions of root systems, expert arborists may reasonably be expected to know where to investigate and what to look for when assessing interactions between roots and structures.
It is reasonable for expert arborists to identify and measure cracks and quantify apparent movement of structures from vertical or horizontal. Based on the appearance of cracks, and the patterns they display, expert arborists regularly distinguish between uplift, slumping, or directional heaving of structures, and provide opinions on their arboricultural causes. Conversely, quantification of forces, or specifications for restorative construction are outside the realm of arborists’ expertise.
I therefore accept the applicant’s contention, at p 4 of his response to the respondent’s submission, that Mr DeJong’s evidence may be relied upon, but only within the parameters described above.
Additionally, speculative claims are set aside by the Court, thus some of Mr DeJong’s opinions may be rejected on this basis. Nonetheless, I do not accept Mr Hannam’s submission, at par 34, that Mr DeJong’s “report is of no assistance in the resolution of this enquiry”.
As the respondent submitted no arboricultural evidence and any speculative claims by Mr DeJong shall be set aside, it is reasonable to rely on the arboricultural expertise I bring to the Court, accrued over more than four decades. Assessment of trees and determination of causation arising from interactions between trees and damaged structures is regularly required of arborist Commissioners in proceedings under the Trees Act. Numerous such examples are available for perusal at NSW Caselaw.
Considering the applicant initially reported wall damage in 2008, and the applicant’s submissions regarding the Frangipani tree, which was in situ until 2010, I find that the Frangipani tree is relevant to the proceedings. To this end, I am satisfied that the Frangipani tree meets the requirements of s 4(4) of the Trees Act. Section 4(4) says:

At par 4 of his submission, Mr Hannam contended that regardless of s 4(4), because the Frangipani was removed in 2010, “[t]he applicant’s claim in relation to the Frangipani tree is therefore time-barred by virtue of the Limitation Act 1969, which required the claim to have been commenced within the 6-year period running from the date on which the cause of action first accrued to the applicant.”.
In spite of the applicant’s solid arguments, I accept the respondent’s submission that the requirements of the Limitation Act 1969, exclude the Frangipani tree from a claim of compensation.
The exception to the six-year period, beyond which claims of compensation are excluded under the Trees Act, generally applies to relatively inaccessible, ‘hidden’ foundations of dwellings. I do not accept that the conspicuous retaining wall is a foundation that meets this description, nor the intent of the exemption. Additionally, I am not persuaded by the applicant’s argument for excluding the usual application of the Limitation Act 1969, on the basis of the respondent’s ongoing obligation to address risk posed by the wall.
Initial applications under Pt 2 of the Trees Act, with respect to claims of damage or injury, were heard in late 2006 or 2007. Therefore, an application under the Trees Act, which proposed orders for compensation for the repair cost of wall damage allegedly caused by the Frangipani, had been an available option for the applicant since wall damage was initially identified and reported in 2008.
Nonetheless, the applicant may seek orders for compensation, or, in the context of these procedures, relief from the respondent’s proposed order for half the cost of wall reinstatement, based on wall damage by the Hackberry tree and on factors that may have compounded such damage, which are considered at s 12 of the Trees Act.
Section 12(h) requires the Court to consider, before determining an application, whether “anything, other than the tree, has contributed, or is contributing” to any such damage or likelihood of damage, as does s 12(i), to such likelihood of injury to any person.
Regardless that engagement of the Limitation Act 1969 disqualified the applicant from compensation for wall damage allegedly caused by the Frangipani tree around 2008*,* if the Frangipani tree is found to be a cause of wall damage, then the requirements of s 4(4) of the Trees Act are satisfied, and the Frangipani tree is ‘a tree subject of the application’ under s 7 of the Trees Act. Should I be wrong, however*,* and engagement of the Limitation Act 1969 prevented engagement of s 4(4) of the Trees Act, it follows that the Frangipani tree would then not be ‘a tree subject of the application’. In that case, provided the Frangipani tree was found to be a cause of wall damage, it may be considered by the Court under s 12(h) of the Trees Act, as anything, other than the tree, that has contributed, or is contributing to any such damage or likelihood of damage. Therefore, I am satisfied that the Court is entitled to consider the role of the Frangipani tree with respect to the wall to determine which, if any, of the above scenarios apply. The alternative would be to pretend that the Frangipani tree had never existed and that would be absurd.

Prior to being pruned by the respondent in August 2024, Council noted the height of the Hackberry tree as 8m. In his application, Mr Kent said it was 6-7m tall with a canopy spread of about 5m. In Mr DeJong’s arborist report, the Hackberry was estimated as 7m x 4m with diameter at breast height (DBH) (at 1.4m above ground level) of 200mm. Based on my site inspection, consideration of the tree’s root flares, Mr DeJong’s Photo 11, and Photo 14 and 15 in Mr Prasad’s engineering report, my conservative estimate of the Hackberry tree’s trunk diameter near ground level was about 400mm-500mm.
Mr DeJong’s Photo 2 displayed the Hackberry tree’s canopy well above and over the respondent’s dwelling roof and spread across the yard. In Mr DeJong’s Photo’s 2, 11, and 12, the dense canopy, the turgidity of leaves, and the lustre of the bark, showed the Hackberry tree was healthy and growing vigorously on 14 January 2024. From Figure 1, an aerial view, the Hackberry tree appeared to dominate the northern side of the respondent’s rear yard.
At Observation 3.0(b) Mr Prasad noted the Hackberry tree was approximately 1.7m from the building wall and approximately 100-200mm from the boundary wall. The applicant’s side of the wall at this location was bowed, cracked, and bulging, directly in line with the tree’s base on the respondent’s side of the wall. This was consistent with the offsets from plumb quantified by Mr Prasad at three locations along the wall, as shown in his Photos 29-31, and with the plan view of the wall in the respondent’s 2024 survey.
Viewed from the respondent’s land, the dominant primary root on the northern side of the Hackberry tree, estimated to be 90-110 mm in diameter, was very close to the wall and appeared to descend diagonally northward at an angle of about 30 degrees.
Considering the distinctive northward lean of the retaining wall, shown in this location in Mr Prasad’s Photo 30 as 126mm/m, this root would probably contact the back of the wall relatively close to the soil surface, as the wall’s marked lean resulted in the southern face of the wall being further south the deeper the root penetrated.
At 3.0(h) of Exhibit 3, Mr Prasad said, the “[h]ackberry roots are partly over the concrete slab and against the boundary wall”, and he referred to Photos 14-16, which clearly illustrated the nexus between the tree’s main roots and the wall, especially Photo 15. Photo 7 was labelled, “[v]iew of the hackberry tree and the boundary wall close to the tree”.
Two relatively large primary lateral roots, located within about 75mm of the wall, respectively faced east north-east, and west. These roots were also likely to contact the wall about 200-300mm below the soil surface and deflect along and down the wall. The propensity of these roots to impact the wall below the soil surface was again probably exacerbated by the wall effectively coming closer to the tree’s web of roots as soil depth increased, as a result of the wall leaning towards the north.
At p 17 of his report, Mr DeJong said, “…the tree’s trunk is butting against the wall” and, “[g]iven the proximity of the tree to the wall and the extent of the TPZ (Tree Protection Zone) underneath it (the wall), it is evident that the tree has caused damage to the wall”.
In the absence of excavation, this was not ‘visibly evident’. However, Mr DeJong opinion was reasonable, as unrestricted roots of a Hackberry tree, with proportions noted at [88], and with a TPZ of 2.4m, in accordance with AS4970:2009, Protection of trees on development sites, may reasonably be expected to spread laterally about 3m or more in all directions. When a Hackberry tree of such proportions was located within 100mm of the wall, damage to the wall was very likely.
Generally, trees are not primarily anchored and fed by a tap root (like a carrot). Provided they have sufficient space, most tree roots grow laterally amongst topsoil where oxygen is readily available. Roots branch frequently to form a vast web. The overall root web usually spreads well beyond the spread of a tree’s canopy. Primary and secondary woody roots closest to a tree’s trunk/root junction (base) have considerable capacity to damage structures.
As they age, roots grow in girth and become woody. As they progressively thicken against encountered structures, they exert increasing pressure. A critical role of roots is providing anchorage to maintain stability of trunks and branches. A functional root system must spread sufficiently to maintain anchorage and stability of above ground parts and is proportional to the volume of the tree’s canopy. Therefore, structures in close proximity to a tree are particularly prone to the impact of thickening roots emanating from a well anchored base.
In the 2010 Siga Engineering report, there was no reported observation of the retaining wall having shifted from its foundations.
Unless the wall and the tree shifted north in unison, from the north-south gaps between sections of concrete displayed in Mr Prasad’s Photo’s 17 and 18, one may reasonably infer that the tree had initially been closer to the wall. This conclusion is corroborated by Mr Prasad’s Photo 30, which showed the wall currently leaning 126mm/m northward near the tree.
Additionally, roots do not necessarily need to be in direct contact with the wall to exert considerable force. As the base of the tree’s trunk and the roots emanating from the trunk grew thicker, longer, and woodier, thickening of the tree’s base and adjacent roots was likely to increase compaction of surrounding soil, thus indirectly exerting pressure onto the wall, prior to direct wall contact by the roots.
The pronounced surface roots growing above and across the concrete surface towards the southeast, west, and south southwest, did not appear to be obvious or major causes of wall damage. However, they were indicative of the probable accumulation of organic matter and humus conducive to the growth dense roots above the concrete surface that almost certainly increased the Hackberry tree’s growth rate.
This was facilitated by the respondent’s apparent lack of back yard maintenance over about 15 years. In Photos 2 and 12 of Mr DeJong’s report, vines and weeds were visible across the ground surface, up the wall, and on the roof of the rear of the respondent’s dwelling.
Hackberry is ubiquitous and is generally deemed a weed because its abundant seeds spread and germinate readily. Young trees rapidly anchor in the soil. They generally grow into a large tree fairly rapidly, and may exceed 20m x 20m, with a trunk diameter around 1m.
Hackberry trees ordinarily have a large and extensive root network relative to canopy size and often cause damage to proximal structures. As with Woollahra, most Councils exempt Hackberry trees from requiring permission for removal due to their ‘weediness’ and this propensity to rapidly cause structural damage.
Unsurprisingly, evidence of a causal link between a tree and structural damage is most readily exposed by proximal excavation. The Court provided guidance to this effect in Stevens v Russell [2016] NSWLEC 1233; at [41]. Here, however, due to the wall’s instability and potential danger from collapse, excavation around the tree was ill-advised.
In submitting that the Hackberry tree was not a cause of wall damage, the respondent relied on a summary of Mr Prasad’s opinion that failure of the boundary wall was a combination of:
Hydrostatic pressure associated with the seeping of water through gaps in the concrete surface slab in the Respondent’s backyard and subsequent accumulation of water behind the wall (para 4.1).
The structural inadequacy of the wall which appears to have been constructed approximately 90 to 100 years ago (para 4.1). Brick walls generally have a 50-year design life (para 4.3).
The presence of a timber screen (being the lattice structure) between the Applicant’s rear deck and the boundary wall which provided lateral restraint to the upper section of the wall causing it to crack horizontally at the lower section. That cracking resulted in lateral shift in the top section of the wall due to the lateral restraint from the rear deck (para 4.1).
Additional pressure to the wall associated with wind loading from the timber screen” (par 4.1).
Next, the respondent said, Mr Prasad makes reference to the state of the wall as at the date of the SIGA 2010 report, stating (para 4.2):

I am not persuaded by Mr Prasad’s opinion, nor the respondent’s summary of same. Upon consideration of Mr Prasad’s range of high-resolution photos, and his ‘Observations’, at 3, and Opinions, at 4, I am not satisfied that his opinion is reasonable.
The fault with Mr Prasad’s opinion is not what it includes, but what it omits. Perhaps ironically, in the absence of excavation, the most compelling evidence substantiating the Hackberry tree’s role as a cause of wall damage was derived from Mr Prasad’s photos, and, to a lesser extent, his report. In my above reasoning, I repeatedly referred to both.
As an unsurprising consequence, Mr Prasad’s substantiation of his opinion was absent of a reasonable explanation for claiming the Hackberry tree was not a cause of retaining wall damage, for the following reasons:
In his report, at 4.1, par 4, Mr Prasad said, “In our opinion the structurally inadequate boundary wall and the additional hydrostatic pressure is causing the wall to lean towards (the applicant’s property) at the bottom section. From the photos provided by the owner’s daughter (Appendix A), it appears that the timber screen wall is sandwiched between the deck and boundary wall. Due to this the deck was providing lateral restraint to the upper section of the wall. As the wall deflected towards (the applicant’s property) and due to the restraint from (the applicant’s) deck the boundary wall has cracked horizontally at the lower section. As the lean towards (the applicant’s property) progressed the horizontal crack deteriorated to the point where the cracks have resulted in lateral shift in the top section of the wall due to the lateral restraint from (the applicant’s) deck.”
At 4.2, par 1, Mr Prasad said, “The hackberry tree is located approximately 100mm-200mm from the boundary wall and was trimmed down to the height of the boundary wall at the time of inspection. The tree has roots partly extending above the slab. From our visual inspection it appears that the tree roots are growing behind the retaining section of the boundary wall. The cracks observed are running full length of the boundary wall of similar magnitude. These cracks were present and reported in the structural report by SIGA structural engineering in 2010 when the hackberry tree was not there but has worsened over time. Therefore, in our opinion the tree roots have not applied any additional pressure onto the retaining/boundary as the cracks are the same or worse towards the rear wall where there are no trees, and the tree is not leaning towards the boundary wall and the tree trunk is approx. 100-200mm away from the boundary wall.”
At 4.2, par 2, Mr Prasad said, “Also, in our opinion the tree in its current condition (trimmed down) has not affected the stability of the (applicant’s) deck as branches are contained in (the respondent’s) property and roots would have only extended around and under the boundary wall.”
Although documents initially provided to Mr Prasad did not include a photo of the tree prior to pruning, considering his reported professional experience over 24 years, including forensic analysis, his experience probably included consideration of the interaction between tree roots and structures. Had Mr Prasad not undertaken such work, he did not have appropriate expertise to provide opinion about the Hackberry tree’s impact on the wall.
Mr Prasad noted the tree was located “100mm-200mm from the boundary wall”. Mr Prasad’s inspection was less than three weeks before the hearing, at which time, my estimate of the tree’s trunk diameter at ground level was about 400-500mm. Mr Prasad said, “[f]rom our visual inspection it appears that the tree roots are growing behind the retaining section of the boundary wall” (4.2(1)). At 4.2(2), Mr Prasad said “roots would have only extended around and under the boundary wall.” Mr Prasad’s Photo 15 clearly displayed the tree’s largest visible root, which was about 40mm from the wall and 100mm in diameter at ground level, descending diagonally towards the wall.
Having observed and photographed this reality, Mr Prasad opined, “the tree roots have not applied any additional pressure onto the retaining/boundary wall” (emphasis added). Mr Prasad based this opinion on the presence of the cracks shown in the 2010 Siga report that predated the Hackberry tree, that the cracks were the same or worse towards the rear wall where there were no trees, and that the tree was not leaning towards the boundary.
However, the 2010 Siga report noted a 70mm shift northerly at about 900mm above ground level at the western end of the wall and a lateral crack at this level for the length of the wall. Photos in the Sega report showed that the crack was more pronounced at the western end of the wall in 2010. There were also no other cracks in the wall in 2010, which inferred to me that the wall may move as a unit. The tree lack of lean towards the boundary was largely irrelevant.
Further, Mr Prasad’s photos from the applicant’s side showed distinct bulging and cracking of the retaining wall, in the specific area of the wall around the tree. Mr Prasad’s Photo 30 indicated that near the tree, the wall was leaning 126mm/m northward, further than in his comparative Photos 29 and 31, from two other locations.
In spite of recent pruning, the Hackberry had been a tree of considerable size. Conservatively, it had been about 7 m tall with a canopy spread of 4-5m. Considering its size, the tree would require a relatively substantial root system for adequate anchorage and uptake of water and nutrients. Considering the observed location of the tree’s trunk and primary roots very close to the wall, and the direction of the roots, the tree’s main roots were located close to the back of the wall.
In light of all these considerations and regardless of other causes of wall damage, a conclusion that the Hackberry tree was not a cause of retaining wall damage, is not reasonable.
I was also not persuaded that the lattice screen was responsible for wall damage by wind loading because I was not satisfied the lattice was attached to the wall. However, I will address the lattice screen in more detail, within considerations under s 12 of the Trees Act.
Dr Amin’s opined that wall damage was caused by a combination of factors. The cause initially noted was, “[h]ackberry tree (and its roots) directly adjacent to the wall. Roots will grow and impose a lateral pressure on adjacent structures which wall is not designed to sustain.”
Consequently, I prefer Dr Amin’s opinion, particularly as Mr Prasad’s opinion was discredited.
In Fang v Li [2017] NSWLEC 1503; at [58]-[60], Galwey AC established a ‘Tree dispute principle: demonstrating cause of structural damage’, detailing the Court’s expectations for reports by Expert Engineers. It is in the interest of Expert Engineers to consider this judgment.
Mr DeJong’s other two opinions about the Hackberry tree causing wall damage were insufficiently supported by evidence. Therefore, they were set aside.
Although excavation of roots was not reasonably possible in this case, based on my observations and evidence adduced from exhibits, I was satisfied of a distinct causal link between visible primary roots of the Hackberry tree and the retaining wall damage.
Consequently, I am satisfied the Hackberry tree is a cause of wall damage, amongst various causes. Though the wall was mainly located on the respondent’s land, under s 3 of the Dividing Fences Act 1991, “dividing fence means a fence separating the land of adjoining owners, whether on common boundary of adjoining lands or on a line other than the common boundary.” A dividing fence is the property of adjoining owners. Further, the tree need only be ‘a’ cause of damage to satisfy the jurisdiction.
This is discussed in Robson v Leischke (2008) 72 NSWLR 98; [2008] (Robson*)* at [179]-[180]; where Preston CJ stated:

At para 59(i) of the Respondent’s Submissions, Mr Hannam claimed that “the Hackberry tree is one of several causes of the damage, and not a substantial cause.” At para 59(ii), he said, “[a] certain degree of wear and tear is expected to arise with any structure over time”, which “must be considered by the Court when determining the extent to which a tree may or may not have caused the alleged damage”.
As s 10(2)(a) of the Trees Act is satisfied, s 9 enables the Court to make any such orders it thinks fit to remedy, restrain, or prevent damage to property, or to prevent injury to any person. In order to determine, what, if any, orders should be made, the Court must consider the matters in s 12 of the Trees Act.
As the tree had been reduced to trunks about 1.5m tall, the majority of elements considered at s 12 had been rendered irrelevant. However, the contribution to damage by factors other than the tree, is considered at s 12 (h), and discussed by his Honour in Robson; at [204]-[210].
In the engineering reports, Dr Amin and Mr Prasad agreed that:
The wall was “acting as a retaining wall and boundary wall” between the two properties. The lower wall section retains soil in (the) respondent’s rear yard to a height of about 900mm.
The upper fence section is single brick, (it is) unknown if retaining wall section increased to double skin wall.
The wall appeared about 90 years old.
No in-ground drainage (was) observed at the rear of the wall, and (was) unlikely to be present. Water accumulating behind wall (was) causing additional hydrostatic pressure … “which the brick wall is unable to resist” (per Mr Prasad).
Wall structurally inadequate relative to modern design codes. Deterioration due to age-based wear and tear.
Dr Amin said a rendered single skin masonry wall was not structurally adequate to resist loads imparted by saturated soils and tree roots. Dr Amin opined that, even if the wall increased to double skin in the lower retaining wall section, it would still be considered theoretically structurally inadequate.
Mr Prasad claimed that a timber screen on the applicant’s deck was a cause of damage.

In contemplating whether the Frangipani tree contributed to wall damage, and if so, to what extent, consequent to the removal of the Frangipani tree in 2010, the Court relied on circumstantial evidence.
The applicant claimed the Frangipani tree was located adjacent to the wall in the north-western corner of the respondent’s rear yard, as indicated on his site diagram in Exhibit B. This location was unchallenged by the respondent.
The applicant claimed the Frangipani tree was the cause of the wall’s initial damage, the 4mm wide crack along the wall’s full length, first noticed in 2008.
In Mr DeJong’s report, the Frangipani tree was estimated to have been 6m tall with a canopy spread of 4m and trunk DBH of 300mm. At p 9, Mr DeJong said his estimates were based on Mr Kent’s photographs of the Frangipani, but I failed to find such photographs in Mr Kent’s various exhibits.
The Woollahra Council Tree Preservation Order 2006, in force in 2010, applied, at (3)(a), to “[a]ny tree with a diameter spread of branches greater than 3m or with a height greater than 5m, irrespective of the spread of branches”. Given that the respondent gained Council permission to remove the Frangipani tree, it is reasonable to assume the Frangipani tree’s height exceeded 5m and or its canopy spread exceeded 3m, and that the Frangipani tree was removed after Council permission was granted on 30 July 2010.
Mr Simone, of Siga Structural Engineering, inspected the wall on 30 October 2010. In Photo 3 of Siga’s subsequent report, the Frangipani tree was absent from the yard’s north-western corner. However, in Photo 1, a Google aerial view indicating the location of the wall, the canopy of a medium sized tree can be seen on the northern side of the respondent’s back yard, overhanging the back wall and the boundary wall, and covering about half of the eastern side of respondent’s back yard. Presuming the tree’s trunk was fairly central relative to its canopy, this would match the applicant’s unchallenged submission, that the Frangipani tree was located in the north-western corner of the respondent’s yard.
Further, the considerable size of the canopy visible in Photo 1 would represent a large specimen for ‘a Frangipani tree’. This was consistent with the applicant’s submission that the Frangipani was a “tree of significance” (Response to Respondent’s submissions, p 4).
On the basis that the Frangipani was a “tree of significance”, the applicant claimed Council would not allow removal of the tree without a good reason. Mr DeJong reiterated this claim because, “Council gave permission to remove a tree of high retention value.” While I accept the respondent’s submission that these claims were unsupported by evidence, since the 1990’s, Woollahra Tree Management has required explicit substantiation for removal of trees prescribed under Tree Preservation Orders and subsequent Development Control Plans. Therefore, I accept the applicant’s contention that Council would not have permitted removal of the Frangipani without a good reason.
The apparent absence or scarcity of back yard maintenance by the respondent between the removal of the Frangipani in 2010, and 2024, corroborated that it was unlikely the Frangipani tree was removed “for no good reason”.
The Siga report, dated 8 November 2010, noted the purpose of the prior inspection as, “[r]espond to Council’s correspondence dated 2 August 2010, a proposed order”.
The Siga report said, “the Northern boundary single skin wall appears to have shifted Northerly some 60mm”, but “[t]he wall does not appear to be out of plumb considerably when measured from your side.
From the applicant’s property, Mr Simone observed, “[a] horizontal crack” about 4mm wide “running along the length of the wall at approximately 900mm above ground level …” From the rear access (laneway), Mr Simone observed, “[a] 70mm shift in the wall Northerly at about 900mm from its base...”
Photo 3 showed the wall broken near the junction with the western boundary brick wall, down a roughly vertical crack which extended to near the respondent’s ground level. The main body of the wall appeared approximately 60 mm north of a short residual section that remained attached to the boundary wall. The gap between the walls appeared about 100 mm wide. The yard was largely clear of vegetation, except for a substantial pile of debris resting against the middle of the boundary wall which appeared to include Frangipani stems.
Paragraph 11 of the respondent’s 2024 survey noted, “[i]n my opinion ground pressure from the higher Lot B is pushing the wall north and hence it has cracked near the ground level of Lot B along the entire length of the wall.” This was unchallenged by the respondent.
I therefore accept the surveyor’s opinion regarding the wall being pushed northward. The surveyor said the cause of the northward lateral movement was ground pressure. It was unknown if the surveyor was aware of the prior presence of the Frangipani tree.
Summarising the circumstances described above at [143]-[156], a relatively large Frangipani tree was growing on the southern side of the north-western corner of the wall until at least 30 July 2010. Permission granted by Council was almost certainly contingent on the respondent having provided sufficient justification for removal. The Frangipani tree was removed prior to the Siga inspection of 30 October 2010. The purpose of the Siga’s inspection was to respond to Council’s “proposed order” for the wall, based on Council’s correspondence of 2 August 2010. This was one of nine letters received from Council during 2009 and 2010, following Mr Kent’s 2008 request to Council for wall inspection and assistance.
It appeared that substantial lateral pressure would have been required to cause a vertical crack through bricks and mortar to separate the common boundary wall from the rear wall and move the wall northward by about 60-70mm.
Possible reasons for such northward lateral movement were ground pressure, as opined by the surveyor, the impact of deterioration resulting from natural wear and tear, and lateral pressure exerted by thickening roots and or trunk of the adjacent Frangipani tree. No other reason was submitted by either party, or their experts.
I am not satisfied that such a distinctly lateral force on the wall may adequately be attributed to the impact of deterioration resulting from natural wear and tear.
Considering the circumstantial evidence adduced above with respect to the removal of the Frangipani, in the absence of a better explanation, I am satisfied, on the balance of probabilities, that the Frangipani tree was the most likely major cause of the wall’s northward movement and the initial lateral crack. Ground pressure and natural wear and tear may also have been causes, but much more minor.

Both engineers were of the opinion that the wall was about 90 years old. However, the 2024 survey submitted by the respondent noted the wall was not present on the 1956 title diagram, which showed the original dwelling’s subdivision. The surveyor’s report said the land in both party’s rear yards was about the same level and was separated by an old fence in 1956. The old fence was marked on the 1956 title diagram, which was included in the 2010 Siga report. The applicant’s submission to this effect was unchallenged by the respondent.
Both current engineers said they were unaware if the entire wall was single skin or whether the retaining wall component was double brick thickness. The Siga report did not comment on the retaining wall’s thickness. The applicant claimed the retaining wall was double brick, because such double brick structure could be observed from the retaining wall’s western end. This was unchallenged by the respondent. Therefore, I accept the retaining wall was double brick.
The original title was cancelled in mid-1957 and the respondent’s mother purchased Lot B in 1957. The respondent’s mother was either the original owner of Lot B, or the respondent’s mother bought the property from a very short-term owner.
Though the applicant claimed the respondent’s mother built the wall, it is largely immaterial who owned Lot B when the wall was built as the respondent’s mother is not a party to this matter.
The wall was constructed after 1956 almost entirely on the respondent’s land. The respondent noted being unaware why that was so. Perusal of the 1956 title diagram showed the common boundary west of the boundary line along the dwellings’ party wall, was ‘dog-legged’ towards the north. Nonetheless, the wall was constructed along the same line as the party wall and intersected with the rear boundary wall at an angle that looked perpendicular. This is a likely explanation for the location of the wall, but again, the reason behind the wall’s location is largely immaterial.
The wall benefitted the owners of Lot B as it retained the soil/fill that increased the level of Lot B (by about 900mm) from encroaching northward towards and onto Lot A.
The applicant claimed the wall was built without Council authorisation. Whether the wall was built in compliance with then applicable construction standards is unknown. Nonetheless, neither the respondent nor prior owners elected to replace and upgrade the wall to meet higher construction standards as they came in force in the interim, or to re-locate the wall on the boundary. I am not aware of any legal imperative for the respondent to repair or upgrade the wall until the Council Order for wall repair in 2010.
Mr Kent initially requested wall repair in 2008 after detecting the lateral crack. The respondent became a part owner of Lot B in 2009, after the death of her brother, Richard. The respondent was aware of the applicant’s concerns about the wall, if only because the 2010 Siga report said the wall inspection and report was required to “[r]espond to Council’s” “proposed order”, from Council’s correspondence of 2 August 2010.
The Siga report’s key findings were noted at [152]-[154]. In spite of the observations and recommendations in the Siga report, and Council’s ‘Order to repair boundary wall’, Mrs Aquilina did not undertake wall repair or replacement.
Ms Kallas, the respondent’s daughter, provided no valid reason for the respondent’s noncompliance with Council’s ‘Order to repair boundary wall’.
Therefore, I consider 28 October 2010, the date of the initial Council order, to be the end date for the determination of the relative impact of wear and tear on the wall. In these circumstances, where the respondent’s inaction was ongoing more than 14 years later, failure to provide a temporal limit to consideration of ongoing wall wear and tear, would result in the imposition of unreasonable injustice on the applicant.
In Robson, his Honour discussed acts or omissions by the owner of the land on which the tree is situated; at [206]-[207]:

The respondent, through her inaction to repair the wall (in response to a legal requirement to do so), may be considered to have “adopted, or continued that nuisance”, regarding additional wall damage from wear and tear after 28 October 2010, and to have “created the nuisance” regarding subsequent damage. Various interrelated consequences arose from the respondent’s sustained lack of property maintenance.
The Siga report, received prior to the Council Order, noted the lateral crack at the respondents ground level. No damage to, or deterioration of the retaining wall was reported. However, the report’s ‘Discussion’ included, “[t]he wall in its current condition does not appear to be posing an immediate danger. Its current condition is most likely the result of movement over many years, possibly 50 years or more.”
Contrary to Mr Kent’s allegation, I found no reference in the Siga report to the wall possibly lasting a further 50 years, provided it had regular maintenance.
Based on the 2024 survey, the wall was built after 1956. Thus, the wall was no older than 54 years in 2010. It was said to be non-compliant with then current standards, but this was not caused by Mr Kent. As a consequence of the respondent’s omission to undertake wall repair or reinstatement during approximately 14 years of property ownership following advice in the 2010 Siga report, the respondent accepted limitations in the wall’s strength and function that may have resulted from the wall’s reported structural non-compliance. i.e. the respondent maintained “the nuisance”.
I accept Mr Prasad’s comment, from para 4.3, that “Brick walls generally have a 50-year design life.” Notwithstanding this, the Court has viewed many double brick retaining walls, not dissimilar to this wall in height and length, that were sound and functional after much longer than 50 years, regardless of whether they met current construction standards.
I am satisfied that the Frangipani tree was the probable major cause of the initial lateral crack in the wall and the separation of the western end of the wall from the rear boundary wall. Hitherto, The prior connection of the common boundary wall to the rear boundary wall was likely to have contributed significantly to the wall’s vertical strength and retention capacity.
For all these reasons, I am satisfied that deterioration due to aged-based wear and tear up to October 2010, was a relatively insignificant cause of wall damage.

The lack of action by the respondent to undertake wall repairs as ordered by Council on 28 October 2010, resulted in my determination of the date of the initial Council order being applied as the end date for my consideration of the impact of aged-based deterioration of the wall.
Photos 2, 11, and particularly Photo 12 in Mr DeJong’s report, along with Exhibits 1 and 4 of Dr Amin’s report, displayed weeds and vines covering the surface of the respondent’s back yard and vines climbing up the dwelling’s rear wall and roof. The respondent did not challenge the applicant’s contention that no maintenance had been undertaken in the respondent’s back yard since the removal of the Frangipani and general clearing in 2010.
The impact of increased hydrostatic pressure on the back of the wall resulting from the perished roof gutter had been considered. So too, the likely simultaneous acceleration of tree growth due to increased soil saturation and moisture availability in the Hackberry tree’s root zone behind the wall. The ideal conditions for establishment of tree roots on top of the concrete surface as a result of humus accumulation from decomposed organic matter has been discussed.
The respondent allowed the Hackberry tree to germinate adjacent to the wall, to subsequently grow to about 8m tall and about 5m wide over an unknown time period and to cause significant wall damage. The applicant contended the respondent should have been aware that the Hackberry tree was likely to cause wall damage and removed it long ago, given awareness of prior wall damage caused by the Frangipani tree.
Regardless of the damage by the Frangipani tree, the reasonable homeowner may be, at least, expected to regularly inspect the property. Upon seeing the Hackberry tree was located very close behind a substantial wall, a prudent landowner may be reasonably expected to take necessary measures to prevent and or rectify wall damage as a result of the tree. Regrettably, it appeared that no or few inspections were undertaken, regardless of the applicant’s ongoing requests for wall repair. Therefore, responsibility for issues resulting from this omission sit with the respondent.
The applicant argued, on the basis of the Tree Dispute Principle established in Barker v Kyriakides [2007] NSWLEC 292 (Barker); at [20], that the respondent’s omission contravened a requirement or expectation to undertake reasonable maintenance. However, the applicant had misinterpreted the Tree Dispute Principle in Barker*,* which relates to applicants who make an application seeking Court Orders based on ‘damage’ caused by a respondent’s tree/s, dropping “leaves, flowers, fruit, seeds or small elements of deadwood”. Therefore, Barker is not relevant here.

In Exhibit 1, par 6, the respondent contended that the applicant had attached a wooden lattice to the dividing wall and connected the dividing wall to the applicant’s rear deck with metal rods. In written submissions, Mr Hannam similarly alleged the dividing wall was connected to the applicant’s rear deck with metal rods. Mrs Aquilina also claimed the lattice and rods had since been removed.
In Exhibit 2, at 4.1, par 5, Mr Prasad said, “In our opinion the (Applicant’s) deck has not caused any damage to the boundary wall as it appears that the deck was not directly connected to the boundary wall.”
Mr Prasad had inspected the wall and the deck, but I found no evidence of a recent site inspection by Mrs Aquilina. Mr Prasad’s opinion at 4.1, par 5, directly contradicted Mrs Aquilina’s contention in Exhibit 1, par 6 (and Mr Hannam’s written submission). Therefore, I prefer Mr Prasad’s opinion that the applicant’s deck was not directly connected to the boundary wall and the deck had not caused damage to the boundary wall.
At 4.1, par 5, Mr Prasad continued, “However, the timber screen wall fixed to boundary wall has contributed to the failure of the boundary wall as it has resulted in additional pressure from wind loading. As the boundary wall and timber screen is subject to wind pressure, there is pressure generated from the timber screen wall (even though its perforated) which then results in additional lateral pressure onto the boundary wall. This additional pressure has caused the boundary wall to lean further over time.”
Annexure’s C1-C4 of Exhibit 1 contained photos of the lattice and rods, taken from the respondent’s land on 28 and 29 September 2024. Photo C1 displayed the face of the lattice panels while Photo C2 was a view looking along the wall towards the dwelling. Photo C2 showed that the eastern end of the lattice frame was vertical where it joined the rear dwelling wall, while the central lattice panels leaned southward at an angle similar to the upper wall, which was leaning against the Hackberry tree. Photo C3 was taken by someone leaning over the wall looking down towards the bottom of the applicant’s deck. Bolts protruding out of the wall’s northern side were near slats of the lattice, but there was no evidence of any connection to the lattice. The western edge of the lattice frame directly contacted the eastern side of the vertical post supporting the roof and handrail on the western side of the deck. The western end of the lattice frame did not protrude southward beyond the post. Photo C4 showed the absence of the lattice.
Mr Prasad reported not having seen the lattice. The lattice was removed in September 2024, while Mr Prasad conducted his inspection in October 2024. Nonetheless, Mr Prasad reproduced the photos from the respondent’s Annexures C1 – C3, in Appendix A to his report.
In ‘Observations’, at 3.0(x), Mr Prasad said, “Photos provided by the owner’s daughter (Ms Kallas) shows timber screen attached to the boundary wall with metal fixings into wall. Refer to Appendix A. These fixings were visible at the time of inspection, but the owner’s daughter informed us that timber screen was recently removed. Refer to Photos 24 and 40.”
Mr Prasad’s Photo 24 showed metal fixings protruding from the wall seven courses of bricks (about 550mm) below the deck bearer closest to the common boundary. The caption of Photo 24 said, “Metal fixings, rusted.” Mr Prasad’s Photo 40 showed a view from the applicant’s deck looking down the deck’s southwestern post. Photo 40’s caption included, “Deck and boundary wall. Metal fixing rusted.” Given the elevated position from which Photo 40 was taken, I could not ascertain the location of the metal rods relative to the bearer at the deck’s southern end but no connection between the wall and the deck was evident. Nor did I observe ‘bolt’ holes in the bearer.
The applicant’s evidence included a letter from David Crafts of David Crafts & Co Pty Ltd, dated 2 November 2024 (Exhibit N). Mr Crafts said he was a builder who worked in the Eastern Suburbs. His letterhead provided his Licence number and ABN. Mr Crafts noted, “on previous inspection” of the applicant’s rear deck and boundary wall, “the timber lattice screen attached to (the applicant’s) deck was securely fastened to both the southern house wall and the handrail post on the west side”, with “14g bugle screws, as is standard practice, which provides a firm and stable connection”. “… [t]he lattice was not fixed with steel bolts as suggested by the engineer”. The steel bolts, “… are old, pre-existing components that are rusted and were never part of the installation or reinforcement of the lattice. They do not contribute to the stability or structural integrity of the lattice”.
Though he contended that Mr Crafts’ evidence was not critical, Mr Hannam made no application for exclusion of Mr Crafts’ letter.
Contrary to Mrs Aquilina’s contention in Exhibit 1, par 6, the steel bolts were still in place and were viewed at the hearing. The bolts were rusty and appeared to be very old. I saw some bolts had damaged threads that would probably prevent attachment of nuts. Consequently, I accepted the applicant’s submission that the bolts predated his occupation and were not connected to the lattice.
Mr Prasad’s opinion about the lattice appeared primarily based on the respondent’s photo from Annexure C3, provided by Ms Kallas, and hearsay. However, because C3 was taken over the wall, the photo was distorted with the foreground amplified while the more relevant background was minimised. Bolts protruding out of the wall’s northern side were near slats of the lattice and tips of some bolts appeared to contact lattice slats, but there was no evidence that bolts were connected to the lattice. The fact that some bolts were covered with render was not useful evidence as I could not gauge the age of the render.
The most relevant evidence was the location of the bolts near the lightweight internal lattice slats, rather than the frame. Lattice slats are generally only about 6 - 8 mm thick and are made of light Pine. Therefore, bolts attached through or between lattice slats would not have provided much stability, and such lattice slats would probably have twisted, split and broken from sustained wind impact. The lattice was present in photos in the 2010 Siga report. It was thus unsurprising that the lattice slats were showing their age in C2 and C3. After about 15 years in situ, however, there was no evidence of the lattice slats twisting or splitting etc. Further, no bolt holes were evident through the sides of either the lattice slats or the surrounding frames. Consequently, I was not satisfied that Photo’s C1-C3 substantiated the respondent’s claim that the lattice screen had been attached to the wall.
Conversely, in the left side forefront of C3, the western side of the lattice frame is consistently contacting the deck’s west side post, while C2 showed the vertical eastern side of the lattice’s frame against the dwelling wall. Notwithstanding that I could not see the screws used to connect the frames, these images matched the description of the connection of the lattice screen in Mr Crafts’ letter.
In summary, Mr Prasad’s photos of “rusty bolts” provided almost no insight into alleged lattice attachment. As Mr Prasad had not observed the lattice, his opinion appeared based on Ms Kallas’ interpretation of the photos.
Therefore, I was not satisfied the respondent had proven, on the balance of probability, that the lattice had been attached to the wall. Conversely, Mr Crafts’ opinion in support of the applicant was corroborated by evidence in Photos C2 and C3.
Though aspersions were cast on the applicant’s motive for removal of the lattice in the Respondent’s written submission, this was not pursued at the hearing. Similarly, the respondent alluded to a nefarious motive behind the applicant’s recent cutting of decking boards, but sought no clarification.

The respondent proposed that the wall be reinstated on the boundary. Paragraph 59(iii), of the Respondent’s submission noted, “As observed in the respondent’s 2024 surveying report, the respondent’s property is benefited/burdened by a cross easement affecting the party wall on the common property boundary.” The respondent added, “in other words, it was intended that the dividing wall would sit on the lot boundary, but for reasons unknown to the parties, the wall sits predominantly on the Respondent’s land.”
I am not satisfied, however, that an intention that, “the dividing wall would sit on the lot boundary” necessarily explained the cross easement. The respondent submitted that regardless neither party knew the reason for the wall’s location on the respondent’s land, “it was intended that the dividing wall would sit on the lot boundary”.
If the respondent did not know why “the wall sits predominantly on the respondent’s land”, it follows that the respondent did not necessarily know why the wall was not located on the boundary. Thus, the respondent’s claim to know of an intention to position the wall on the boundary appeared contradictory. This implied that the person who located and built the wall made an arbitrary decision, a mistake, or chose the location on a whim, or similar. I consider this unlikely.
An examination of the 1956 Subdivision Plan in the 2010 Siga report, displayed a plausible reason for the wall’s current location. Beyond the dwelling, the boundary deviated towards the Applicant’s property from the line formed by the dwelling’s party wall. However, the wall was positioned along the same line as the line formed by the dwelling’s party wall, which provided scope for perpendicular junctions between the wall and the dwelling, and between the wall and the rear boundary.
This may not have been the intention behind the wall’s location. Nonetheless, it provided a reasonable explanation, while the Respondent’s submission did not. Consequently, I am not satisfied the respondent had proven an intention “that the dividing wall would sit on the lot boundary”.
Either the respondent’s mother, or a short-term owner in 1956, was responsible for the location of the current dividing wall. The applicant shared no responsibility for the initial choice of wall location.
Nonetheless, reinstatement of a replacement wall on the boundary is reasonable, and the respondent’s proposal was supported by the applicant.

The Frangipani tree that previously grew near the north-western corner of the respondent’s back yard was the probable major cause of the initial 60-70mm northward movement of the north-western end of the common boundary wall in or around 2008. This northward movement of the wall probably occurred in conjunction with the adjacent near vertical crack, and the wall’s separation from the rear boundary wall near the wall’s north-western corner, along with the lateral crack about 900mm above the applicant’s ground level, along the wall’s entire length.
After removal of the Frangipani tree and other vegetation in 2010, the respondent very rarely, or never, inspected or maintained her back yard until August 2024, when the yard was cleared, and the Hackberry tree was lopped. The respondent’s property was vacant during this approximate 15 years period.
Therefore, conditions were ideal for the establishment and unabated growth of the Hackberry tree. Simultaneously, weeds and vines that grew and decomposed across the respondent’s back yard, enhanced Hackberry root growth above the back yard’s concrete surface. Mr Prasad referenced these unusual roots in his text and photos.
As the Hackberry tree’s primary roots thickened and extended very close to the back of the wall, they almost certainly levered the retaining wall northward. During the 15-years of property vacancy and neglect, the respondent’s rear house gutter deteriorated and disintegrated such that rainwater from the roof flowed into the area near the Hackberry tree at the back of the wall.
Both engineers noted hydrostatic pressure on the back of the wall as an important cause of wall damage, compounded by the likely absence of sub-surface drainage. Considering the relatively large water catchment provided by the dwelling roof relative to the catchment provided by the small concrete area around the back of the wall, it was highly likely that the broken gutter resulted in a significant increase in water volume and thus hydrostatic pressure on the back of the wall.
The respondent’s mother purchased Lot B in 1957, within one year of the combined dwelling’s subdivision. The respondent’s 2024 surveyor indicated the wall was built after 1956. The respondent had chosen not to alter the wall’s condition since initially inheriting part ownership of the property in or around 2009, and thus adopted and continued the nuisance arising from the likely absence of sub-surface drainage behind the wall, and other structural inadequacies.
In 2010, the respondent ignored advise from her engineer from Siga Structural Engineering that, “it (the boundary retaining wall) and the single skin fence should be upgraded (within the next six months) to suitable relevant standards”. Significantly, the respondent also ignored the Council Order of October 2010, to repair the wall within 90 days.
The respondent provided no valid reason for non-compliance with the Council order. As the wall was primarily located on the respondent’s land, unilateral repair was unavailable to the applicant. Consequently, I deemed the date of the 2010 Council order to repair the wall, as the end date for consideration of the impact of age-based wall deterioration. I considered any later date would cause injustice to the applicant.
In 2010, the wall’s maximum possible age was 54 years. The 2010 Siga report noted the northward movement of about 70mm at the wall’s western end, the adjacent near vertical crack and separation of the wall from the rear boundary wall, and the 4mm wide lateral crack along the wall’s length, about 900mm above the applicant’s ground level. A 35mm/1.1m rotation of the retaining wall towards the applicant’s land was also reported. The report said the current condition most likely resulted from movement over possibly 50 years or more, and the wall’s current condition did not appear to be posing an immediate danger.
Based on my prior findings, the northward movement of about 70mm at the wall’s western end, the 4mm crack along the length of the wall and the separation of the wall from the rear boundary wall, were probably caused by the Frangipani tree. Further, the prior perpendicular junction between the two walls would have probably contributed to maintenance of the vertical strength of the common boundary wall. Therefore, the 35mm/1.1m forward rotation of the wall may have been caused or exacerbated by the wall’s prior breakage, and disconnection from the rear boundary wall.
Based on this adduced evidence, in the absence of damage that was probably primarily caused by the Frangipani tree, there was nothing else about the wall’s condition in 2010 that was likely to have prompted the applicant’s concern.
In my opinion, the Hackberry tree was the most significant cause of the wall’s current condition. The respondent was responsible for the cumulative impact of wall damage caused by the Frangipani tree, the Hackberry tree, the absence of sub-surface drainage behind the wall, the disintegrated roof gutter, and the consequent significant increase in hydrostatic pressure behind the wall. Relative to the impact of these five causes, I am satisfied that deterioration due to wear and tear up to October 2010 provided an insignificant contribution to the wall’s current condition.

Other than the relatively insignificant impact of wear and tear before October 2010, responsibility for all of the aforementioned cumulative causes of current wall damage rests with the respondent.
In Exhibit 1, par 9, Mrs Aquilina inferred that wall repairs were prevented by her disagreement with Mr Kent’s proposal to, “carry out the work personally to reduce the cost of construction”. Ms Kallas orally submitted that Mr Kent’s preference to manage or supervise works presented a sustained barrier to required wall repair or replacement.
I am not persuaded by these submissions, however, as they fail to reasonably explain why, after advice from the respondent’s engineer and the Council Order to repair the wall in 2010, the respondent undertook no wall repair or restoration works across the following 14 years.
Particularly as the 2010 Order from Council required mere wall repair, I find no adequate reason why, for example, the respondent could not have gained control of the works by offering to pay more than half of the cost to repair the wall, soon after.
The respondent claimed past encroachment beyond the boundary by a section of the applicant’s deck and gutter as one reason it would be unjust to require the cost of wall replacement to be borne solely by the respondent. However, the deck had apparently not encroached beyond the original location of the current dividing fence. Even if the deck had encroached, the respondent had suffered no disadvantage as the respondent’s property had not been occupied since about 2009 and had rarely been inspected for almost the entire duration of the respondent’s ownership. Therefore, I find alleged or actual encroachment by the applicant’s deck or gutter had not caused injustice to the respondent.
The respondent was alerted to the initial damage to the wall in 2008 and to the likelihood of further damage and subsequent likely collapse on numerous occasions over about 17 years. In the interim, the respondent ignored Council orders to repair the wall and render it safe, in both 2010 and 2023. The Frangipani tree was removed in anticipation of the 2010 Council order, but no wall repairs followed. In spite of all these notifications, no remediation of the wall was undertaken by the respondent.
The respondent’s inaction over 17 years cannot be reasonably justified by the respondent’s dissatisfaction with the applicant’s suggestions or preferences. There was nothing more the applicant could do. Therefore, the cumulative wall damage was almost entirely a direct result of acts or omissions of the respondent. Consequently, it is reasonable that the respondent assumes responsibility for, and costs of, tree removal and all requirements for demolition and replacement of the retaining wall, except for two elements.
Firstly, the cost of any modifications required to remove part of the applicant’s deck from encroachment onto the respondent’s property or onto the new wall, shall be paid by the applicant. Similarly, the applicant shall undertake and pay the cost of measures required to provide reasonable access for the wall’s demolition and construction. The applicant, at his expense, shall also rectify encroachment of his gutter beyond the common boundary whilst undertaking pending wall installation.
However, should the applicant’s property be damaged during demolition and removal of the existing wall, or construction of the replacement wall, the cost of repair of such damage to the applicant’s property, shall be paid by the respondent.
Secondly, upon completion of construction of the new wall and receipt of certification of compliance from Council, the applicant shall pay the respondent $3000.00,approximately half the estimated cost of the wall’s fence component.
Other than these two elements, the cost of a structural engineer, surveyor, all costs required to secure Council planning approval, and for demolition of the existing wall and construction of a reinforced block wall of no lesser height than the existing wall, in compliance with current construction standards, and for removal of the Hackberry tree, shall be borne by the respondent.
The respondent shall also pay for builders to install props as an interim measure to mitigate risk of wall collapse, consistent with the recommendation of both engineers.
The wall will not necessarily collapse when the Hackberry tree is removed. To reduce the likelihood of collapse, however, the wall may need to be dismantled ‘brick by brick’. No attempt should be made to remove the Hackberry roots until said demolition is sufficiently advanced that the tree’s trunk base and roots are visible and readily accessible so they may be severed. Given the tree’s now reduced height and bulk, removal of the residual tree may be included in the builder’s scope of works, rather than being undertaken separately by an arborist.
To this effect, the respondent shall include this requirement in the scope of works provided to licenced, insured builders from whom the respondent procures quotations. The builders shall also require project management expertise to co-ordinate sub-contractors, to relieve the applicant of any need for supervision.
Should either party fail to meet the requirements of the following orders, a Notice of Motion for Contempt of Court may be lodged.

The Court orders that:
The application is granted, subject to the following orders:
The respondent shall engage and pay a licenced builder with appropriate insurance, to prop the existing wall to mitigate the risk of wall collapse, within 14 days of the date of these orders.
The respondent shall engage and pay a registered structural engineer with appropriate insurance, to provide plans, specifications, and scope of works for a reinforced concrete block retaining wall with appropriate foundations and sub-surface drainage, of no lesser height than the existing wall, that complies with current construction standards, within 14 days of the date of these orders.
The respondent shall pay for any and all required fees and requirements to promptly secure development consent from Council for demolition of the existing wall and construction of a replacement wall, as described in Order 3.
The respondent shall engage and pay a licenced/registered surveyor with appropriate insurance, to determine and clearly mark the common boundary between the parties’ land, within 14 days of the date of these orders.
Within 40 days of the date of these orders, the respondent shall email the applicant three itemised quotations from licenced, suitably insured builders with project management expertise, for safe demolition of the existing wall, construction of a replacement wall as described in Order 3, and removal of all debris. Within 45 days of the date of these orders, the applicant shall email the respondent a first and second choice of contractor. Within 50 days of the date of these orders, the respondent shall engage either of the applicant’s preferred contractors, prioritising the contractor with the earliest availability to undertake the works.
The applicant shall undertake and pay for deck modifications required to remove all deck encroachment of the common boundary or the proposed wall. Should the applicant’s existing or proposed deck pillars constrain the respondent’s builder’s safe access, the applicant shall install suitably located temporary deck support and remove the existing deck pillars. These works shall be completed within 60 days of the date of these orders. Reinstatement of permanent deck pillars may occur after completion of the wall works.
The respondent shall engage and pay a licenced plumber, builder, or roofer, with appropriate insurance, to replace the disintegrated roof gutter on the rear of the respondent’s dwelling, within 90 days of the date of these orders.
Upon confirmation of development consent from Council, the respondent shall engage and pay the selected builders to demolish the existing wall, construct the replacement wall as described in Order 3, and remove all debris. The works shall be completed within 130 days of the date of these orders. Upon completion, the respondent shall gain certification of wall compliance from Council within 140 days of the date of these orders and email a copy of such certificate to the applicant, within a further 5 days. Within 5 days of receipt of the Council wall compliance certificate, the applicant shall pay the respondent $3000.00 by Electronic funds transfer (EFT).
The applicant shall provide all reasonable access for contractors to undertake the works, upon receipt of at least 48 hours’ notice by email from the respondent or from their appropriately insured contractors, of the date and approximate time of commencement and anticipated duration of works, and a copy of the said contractor’s insurance certificates of currency.
All works must comply with applicable Work Health and Safety legislation and regulations.
All works shall occur during reasonable daytime working hours.

Kent v Aquilina

At a glance

Court

Decision date

Before

Catchwords

Source

Email me a plain-English summary of this case

Catchwords

Judgment

Judgment

Background

Framework for adjudication of the application

The onsite hearing

Submissions

Applicant’s submissions

Respondent’s submissions

Evidence relied upon by the respondent

The applicant’s rear deck

Jurisdictional considerations

Findings

Wall damage - The Hackberry tree

Other causes of wall damage

Hydrostatic pressure on the wall

The Frangipani tree

Wall deterioration over time from wear and tear

Impact of lack of maintenance

The lattice screen

Risk of injury to a person

Other considerations

Wall relocation

The applicant’s deck

Summary

Who should pay?

Orders

J Douglas

Acting Commissioner of the Court

Parties

Legislation Cited (7)

Cases Cited (1)

Kent v Aquilina

At a glance

Court

Decision date

Before

Catchwords

Source

Email me a plain-English summary of this case

Catchwords

Judgment

Judgment

Background

Framework for adjudication of the application

The onsite hearing

Submissions

Applicant’s submissions

Respondent’s submissions

Evidence relied upon by the respondent

The applicant’s rear deck

Jurisdictional considerations

Findings

Wall damage - The Hackberry tree

Other causes of wall damage

Hydrostatic pressure on the wall

The Frangipani tree

Wall deterioration over time from wear and tear

Impact of lack of maintenance

The lattice screen

Risk of i****njury to a person

Other considerations

Wall relocation

The applicant’s deck

Summary

Who should pay?

Orders

J Douglas

Acting Commissioner of the Court

Parties

Legislation Cited (7)

Cases Cited (1)

Risk of injury to a person