Gowland v Ho

Framework for this decision

1. Key jurisdictional tests under Pt 2 of the Trees Act are set out at s 10, where the Court must be satisfied of certain matters before making any orders. Firstly, the Court must be satisfied that the applicants have made reasonable effort to reach agreement with the tree owners (s 10(1)(a)). Secondly, the Court must be satisfied that the tree concerned has caused, is causing, or is likely in the near future to cause, damage to the applicants' property, or is likely to cause injury to any person (s 10(2)). Where an application includes more than one tree, this test must be met for any individual tree before orders can be made for that tree.
2. The Court must also consider a range of matters at s 12 of the Trees Act before (at s 9) making "…such orders as it thinks fit to remedy, restrain or prevent damage to property, or to prevent injury to any person, as a consequence of the tree the subject of the application concerned."
3. On the face of it, the matter seems straightforward. Have trees damaged the applicants' property? If so, considering all relevant matters, what works are required to the applicants' property to remedy, restrain or prevent that damage? And, do the trees need to be removed? On the other hand, there are issues now intertwined with these simple questions that reflect the difficulty the applicants have experienced in reaching this point: who owns the retaining wall; who is responsible for its current condition; who would benefit from its rebuilding; and who should pay for any works?

The hearing

1. The hearing proceeded onsite, allowing observations of the trees, retaining walls and relevant features of both properties. Mr Simington represented the applicants, Mr Doyle the respondents. Available for oral evidence and questions were the expert witnesses who had prepared reports for these proceedings: engineers Peter Waugh and Daniel Bliss (applicants) and David Willows (respondents); and arborists Catriona Mackenzie (applicants) and Jack Williams (respondents). The hearing commenced with a large group made up of the parties and their representatives, experts and the Court roaming to the various elements to be viewed, with the experts making observations, Mr Simington and Mr Doyle pointing out features relevant to their submissions, and the applicants and respondents adding some background information. Oddly, the parties spent considerable effort taking the Court to view the trees from certain locations said to correspond with an historic photograph in evidence. The photograph would be the subject of subsequent cross-examination and submissions regarding the age of trees T1 and T2 and whether they existed at the time RW1 was constructed.

The applicants made reasonable effort to reach agreement

1. It is abundantly apparent from the evidence that the applicants have made reasonable effort to reach agreement on a solution with the respondents. The applicants have kept records of emails and other correspondence. They engaged experts to advise them on suitable options to remedy the situation and included the respondents in some of those discussions. They offered solutions with apportionment of costs and allowed the respondents extensions in time to respond. The respondents do not dispute the scale of the applicants' efforts, although they disagree with some content of supposed agreements. I am satisfied that the applicants made a reasonable effort to reach agreement with the respondents.

Trees have damaged the retaining wall RW1

1. Having already prepared a joint report, the engineers Mr Bliss, Mr Waugh and Mr Willows prepared a "Supplementary Geotechnical and Structural Engineers Expert Witness Joint Report" (the 'Supplementary Engineers' Joint Report') (Exhibit F) following an additional joint conference on 31 May 2021. In this report, they added further comments to their original joint report.

Tree T1

1. The engineers all noted a vertical crack in RW1, 40mm in width, directly adjacent to the Black Bean, T1. Mr Bliss and Mr Waugh agreed that T1 has damaged RW1 by its root growth placing uplift loads on the rigid retaining wall, causing it to crack. Mr Willows disagreed with this in the Supplementary Engineers' Joint Report, stating that the face of RW1 was an additional cosmetic layer added to the original retaining wall, which was behind this face and could not be seen. He stated that only this facing in front of RW1 was damaged, with that damage (at paragraph 16) "… predominantly caused by other factors than Tree 1." However, at the hearing, Mr Willows wanted to correct some of his opinions in the Supplementary Engineers' Joint Report, most notably his finding that a 'facing' layer added to RW1 hid the original structure of that retaining wall. I found this surprising, not because of his mistaken earlier opinion, but because of his history with this retaining wall, his opportunities to inspect the wall and discuss it with the other engineers during multiple joint expert conferences, and his last-minute change of mind. It is not that an expert should not change their mind in light of further investigation or consideration of an issue, but on this issue I found Mr Willows' evidence unreliable.
2. In 2019, after the applicants first discussed RW1 with the respondents, Mr Willows (then employed at a different company) inspected the retaining wall and prepared a report addressed to Mr Ho, the first respondent. In that report he described the retaining wall and its condition in some detail, but he did not suggest that what he was inspecting was an additional layer constructed in front of the retaining wall proper. In 2021, after these proceedings commenced, Mr Willows' opinion in the first joint report prepared with Mr Bliss and Mr Waugh (at paragraph 10) was: "DW stated that additional stone facing may have been placed in front of RW1 at some time after construction, due to a similar appearance of RW1 to that of RW2." Mr Bliss and Mr Waugh disagreed, with sound reasons.
3. Then, in the Supplementary Engineers' Joint Report, responding to opinions of Mr Bliss and Mr Waugh, Mr Willows wrote (at paragraph 6.iv): "DW disagrees to above and says that RW1 is not visible from No. 10. The sandstone and mortar that is damaged is not part of the original wall RW1, which was constructed on No. 8a for the driveway. RW2 is visible from No. 10 in the area described in front of the slope into No. 10. The damage that can be seen in the structure is to the front part of the sandstone and mortar facing that appears to have been applied to the face of the original wall RW1. It is the opinion of DW that based on review of the construction of RW1 in the Philip Haynes affidavit, as well as the photographs of the wall in 1975, that the wall RW1 is unlikely to be damaged. There has been no damage observed to RW1 because it is obscured." There appeared to be no solid reason for Mr Willows' change of opinion, other than observing "…the front part of the sandstone and mortar facing that appears to have been applied to the face of the original wall RW1." At the hearing, Mr Willows retracted this opinion, once again aligning his opinion regarding the wall's construction with that of Mr Bliss and Mr Waugh. Nevertheless, Mr Willows' opinion regarding the cause of cracking to RW1 near T1 was still that it resulted predominantly from other factors.
4. For reasons set out above, I find it difficult to rely on Mr Willows' evidence, preferring the evidence of Mr Bliss and Mr Waugh. I accept their findings that T1 has caused a crack to open up in RW1.
5. The arborists also noted the crack near T1. Ms Mackenzie expressed an opinion (at paragraph 23 of the Supplementary Joint Arboricultural Expert Report) that: "…whilst she is not an engineer, her experience is that a dimensioned block wall structure such as an 'engineered' wall (as opposed to this stone and mortar wall) would normally exhibit typical uplift damage commonly associated with tree root pressure (e.g. wall bowing, vertical and/or step cracking), but in this case, the mortar holding the undimensioned [sic] rock components in place is deteriorating. Uplifting forces from root pressure is [sic] contributing to the movement of rocks and mortar so cracks are appearing in an irregular pattern."
6. Mr Williams stated (at paragraph 26 of the same report): "It is therefore my opinion that it is likely that roots are present in close proximity to the wall, however it has not been demonstrate [sic] that tree roots are applying pressure to the wall and contributing to the damage and a clear link between a part of the tree and damage to the wall has not been established. I rely on the engineering experts to advise if the existing wall construction type would exhibit typical uplift damage commonly associated with tree root pressure."
7. Mr Bliss and Mr Waugh did advise that pressure from T1's roots would result in the adjacent cracking to RW1 and found that this was the major contributing factor causing this crack.
8. At paragraph 41 of the Supplementary Joint Arboricultural Expert Report the arborists wrote: "At [16] of the engineers' report there is agreement that Tree 1 has contributed to the damage of the retaining wall (RW1). This agreement is consistent with the conclusion of the arboricultural experts at paragraph 65 of the arboricultural joint expert report."
9. I accept the findings of both arborists and two out of three of the engineers. I find that T1 has caused damage to RW1 by its root growth lifting a section of the wall, resulting in a crack opening up in the wall near the tree.

Tree 2

1. Both Ms Mackenzie and Mr Williams thought it likely that T2 has contributed to damage to RW1, however both thought further investigation would be required to demonstrate this. Mr Bliss and Mr Waugh wrote in the Supplementary Engineers' Joint Report (at paragraph 17): "DB and PW agree with the opinion of the arborist [sic] in their joint report dated 30 April 2021 that it is likely that Tree 2 has contributed to the damage to RW1."
2. These experts discussed options for undertaking further investigation, not just for the purpose of demonstrating causation of damage, I note, but also for exploring possible solutions to repairing or replacing the retaining wall and retaining T2. Investigative options include ground-penetrating radar (GPR) and digging geotechnical test pits.
3. Mr Willows disagreed with the other experts, writing (also at paragraph 17 of the Supplementary Engineers' Joint Report): "DW is of the opinion that Tree 2 has not contributed to the damage of RW1. DW stated that no root mapping or geotechnical test pits have been carried out to locate the tree roots and needs to be carried out."
4. It seems to me that Mr Willows opinion, that T2 has not caused damage, is based only on a lack of root mapping. That is, he is not saying T2 has not caused damage, only that this has not been demonstrated.
5. Ms Mackenzie and Mr Williams wrote at paragraph 42 of the Supplementary Joint Arboricultural Expert Report: "At [17] the engineers engaged by the Applicant agree with the arboricultural experts' opinion at paragraph 65 of the arboricultural joint report that Tree 2 is likely to be contributing to damage to RW1. The Respondent's engineer does not agree and includes an opinion that root mapping or geotechnical test pits need to be carried out to locate tree roots."
6. I see no need for further root mapping for the purpose of demonstrating causation. Relying on the adduced evidence from both arborists and two out of three engineers, as well as my own observations at the onsite hearing, I am satisfied that T2 has contributed to damage of RW1.

Trees T3 and T4

1. In the Supplementary Engineers' Joint Report at paragraph 18, the engineers wrote: "DB and PW are of the opinion that Trees 3 and 4 are a minor contributing factor to the damage to RW1 due to the cracking present at the wall adjacent to these trees. Several factors would contribute to the damage, with the major contributing factor discussed below. DW is of the opinion that Trees 3 and 4 have not caused damage to RW1. All agree that the major contributing factor to the damage to RW1 is the inadequate design of the retaining wall. The wall is leaning on Trees 3 and 4 and they would be assisting to support the wall locally."
2. Ms Mackenzie and Mr Williams wrote at paragraph 51 of the Supplementary Joint Arboricultural Expert Report: "We agree the Applicant's engineers' opinion that Trees 3 and 4 are a minor contributor to damage to RW1 is consistent with the arboricultural experts' opinion that these trees' contribution to damage to RW1 is somewhat likely, i.e., possible."
3. Again, preferring the opinions of four experts over Mr Willows' unexplained reasons for an alternative opinion, and buoyed by my onsite observations of cracking adjacent to these two camellias, I find that T3 and T4 have caused damage to RW1.

Trees T5 and T6

1. Adduced evidence suggested that two vines with their foliage covering the face of RW1 have also damaged this retaining wall as their adventitious roots have accelerated degradation of mortar between the wall's blocks. The respondents submitted that the vines might originate on the applicants' land, which I accept. The applicants submitted that most of the vines' foliage is on the face of the wall, which is on the respondents' property, so the applicants have no control over it. I could not be satisfied that trees T5 and T6 were situated principally on the respondents' land. I could not be satisfied that they have caused any damage that would warrant the Court's attention.

Have the trees damaged the applicants' property?

1. Above, I have found that all four trees T1-T4 have caused damage to RW1. The relevant jurisdictional test at s 10(2)(a) is whether the trees concerned have caused (or are causing or are likely in the near future to cause) damage to the applicants' property. RW1 runs approximately along the boundary. Several survey plans were included in the parties' evidence. A 2013 survey plan by Burton & Field shows the majority of RW1 on the applicants' property with its face approximately on the common boundary. Regarding another survey plan, by Bee & Lethbridge, the engineers noted at paragraph 14 of their joint reports (Mr Willows having retracted his opinion regarding an additional face added to the wall) that: "RW1 is located on and both sides of the boundary between 8A and 10, as shown on the Bee & Lethbridge survey plan (Ref: 20940, Rev 00, dated 12/8/2020)." The most detailed survey plan is that of SurveyPlus dated 27 August 2019. It shows RW1 beginning at its western end entirely on the applicants' property, but within a few metres the wall reaches the boundary, after which, eastward to where RW1 meets RW2, the wall is at least partially on the common boundary even if most of its width is on the respondents' property. Where RW1 passes all four trees T1-T4, this survey plan supports what onsite observations suggested: that RW1 is a boundary wall. I find its ownership is shared.
2. Various submissions addressed related issues. Mr Simington submitted that the wall was originally constructed entirely within the property now owned by the applicants, but has shifted. Mr Simington submitted that the wall was built to benefit owners of both properties at the time of its construction, whereas Mr Doyle argued it solely benefitted the then owner of the applicants' land. This might be relevant to some determination of negligence under the Conveyancing Act 1919 (the 'Conveyancing Act') should the wall fail, but I see nothing in that act that determines a retaining wall's ownership.
3. RW1 appears as a boundary wall and survey plans confirm it straddles the boundary. I am satisfied that its ownership is shared by the parties, so it is at least partly the applicants' property. It follows that the jurisdictional threshold at s 10(2)(a) is met: the Court is satisfied that trees T1-T4 have caused damage to the applicants' property.
4. RW2 is entirely within the respondents' property. It is included in the application because the applicants say its removal is required to carry out repair or replacement of RW1.
5. It should be noted here that a retaining wall extends further to the east along the common boundary, either a continuation of RW1 or a separate wall of a similar nature. The wall cannot be seen, other than its top, due to the raised soil level on the respondents' land behind RW2, which effectively brought that corner of the respondents' land up to the same level as the adjoining part of the applicants' land. While that soil remains, the wall along the eastern part of the common boundary appears not to be required to support the applicants' land. In giving evidence at the hearing, the engineers said it is not known if this wall is damaged or requires works, and this would not be known without removing the soil north of RW2. The applicants want that soil removed and intend to replace the retaining wall along the common boundary. My findings regarding damage to RW1 do not extend to the retaining wall further east, as there is no evidence that the respondents' trees have damaged that section of the wall.

Jurisdiction to make orders

1. Trees on adjoining land have damaged the applicants' property. The applicants made reasonable effort to reach agreement with the respondents; and they gave the required notice of their application. The Court therefore has jurisdiction, at s 9 of the Trees Act, to make such orders as it thinks fit to remedy, restrain or prevent damage to property as a consequence of trees T1-T4. Here it is appropriate to include Mr Doyle's principal reason for arguing that the Court should refuse the application. Mr Doyle argued that the applicants need a new retaining wall to support their driveway because the existing wall (RW1) is in poor condition for reasons other than damage caused by trees. He submitted that the applicants are seeking contribution from the respondents for works that the applicants need to undertake for reasons unrelated to the respondents' trees. The Court is being asked to remedy damage that is not caused by trees and so not covered by the Court's jurisdiction at s 9 of the Trees Act. I address this further below.

Relevant matters to be considered by the Court

1. Before determining appropriate orders, the Court must consider the matters at s 12 of the Trees Act. I have considered all of those matters and discuss the relevant ones below. It is worth first summarising the parties' relevant submissions.
2. Mr Simington submitted that trees have damaged RW1, which must be rebuilt, requiring the removal of RW2 and the soil it supports. Mr Simington submitted that trees T1, T3 and T4 (and vines T5 and T6) must be removed to rebuild RW1. While Mr Simington conceded that retaining T2 would be desirable, there was no solution at hand for replacing the wall without requiring T2's removal. He submitted that the applicants had received advice from Ku-ring-gai Council ('Council') that Council would be likely to consent to the removal of both T1 and T2. Mr Simington opined that RW1 benefited the respondents and former owners of their property, so they should contribute reasonably to the cost of its replacement.
3. Mr Doyle submitted that the applicants wish to replace the retaining wall for their own benefit and that its replacement is required regardless of any damage caused by trees. Mr Doyle submitted that the retaining wall has only ever benefitted owners of the applicants' land. It is therefore up to the applicants to maintain a wall that benefits them.

Council consent

1. Council consent would be required to remove T2. Council consent would be required to remove T1 if it is more than 3 metres from the respondents' dwelling. Removal of T3 and T4 would be exempt works due to their size or their proximity to the respondents' dwelling (Ku-ring-gai Development Control Plan 2021, Part 13). The applicants submitted that Council advised consent would be granted to remove T1 and T2.

Benefits of the tree

1. Trees T1 and T2 make significant contributions to the respondents' landscape and to the broader environment. In particular, T2 is an indigenous species, part of the local ecological community. Both trees provide shade, cooling and other ecosystem services. Their removal would result in loss to the respondents' landscape and to local amenity.

Other contributing factors

1. Matters to be considered include s 12(h)(i) and (ii) of the Trees Act: (h) if the applicant alleges that the tree concerned has caused, is causing, or is likely in the near future to cause, damage to the applicant's property: (i) anything, other than the tree, that has contributed, or is contributing, to any such damage or likelihood of damage, including any act or omission by the applicant and the impact of any trees owned by the applicant, and (ii) any steps taken by the applicant or the owner of the land on which the tree is situated to prevent or rectify any such damage.

Other causes of damage

1. Although trees T1-T4 have damaged RW1, other factors have impacted the wall far more significantly. The evidence before the Court regarding the wall's condition and its causes is, almost, unequivocal.
2. In 2000, engaged by the then owner of the respondents' property, engineer Jack Hodgson assessed RW1. Mr Hodgson noted cracks and bulges in the western part of the wall. He wrote: "In our [sic] opinion the section of the retaining wall is inadequate to support the loads being imposed on it during periods of prolonged rainfall. These rainfall periods are widely spaced in time and, where the wall section is not grossly inadequate, the deflection is small but is cumulative to failure over a long period of time. In our opinion the wall in question will ultimately fail and the exact time to failure cannot be predicted." Mr Hodgson provided three options for replacing or repairing the wall. Mr Hodgson did not identify trees as a cause of damage.
3. In 2019 Mr Ho, the first respondent, engaged Mr Willows (then working for a different company) to assess RW1. Mr Willows found that "…the wall is in a gradual state of failure, because the observed narrow dimensions of the wall blocks… are not sufficient for the wall to act as a gravity retaining wall." He postulated causes of damage included, among others: the wall not being able to support fill and water loads behind it; rainfall and runoff from the applicants' property increasing the volume of water behind the wall; a lack of surface drainage behind the wall; and finally "Another factor that may have contributed to localised instability and wall damage is the continuing growth of tree roots in front of the wall…". The damage was assessed as being so severe that Mr Willows concluded RW1 posed a high level of risk to property, recommending that an exclusion zone be established within 2 metres of the most damaged parts.
4. In 2020 the applicants engaged Mr Waugh to prepare a report on the retaining walls. He concluded that RW1 should be demolished and replaced due to its condition. He identified inadequate engineering and the presence of T1 and T2 as causes of damage.
5. When asked in their original joint report of May 2021 to identify "The relative responsibility for the damage cause [sic] by the tree/s as opposed to other contributing causes", Mr Bliss, Mr Waugh and Mr Willows answered at paragraphs 21 and 22: "21. All agree that the contributing factors to the damage of RW1 and the driveway are as follows: a) Inadequate structural capacity of the wall to support the retained soils. b) Cracking and movement of the wall from the effect of the trees and their roots that are located directly in front of the wall. c) Inadequate drainage behind the wall increasing hydrostatic pressures on the wall. This includes the natural seepage flowing along the surface of the sandstone. d) The presence of services behind the retaining wall and below the driveway providing a pathway for water behind the wall. 22. All agree that it is not possible to definitively determine the contributing percentage of each of the above factors. All agree that the inadequate capacity of the wall would be the major contributing factor."
6. In the Supplementary Engineers' Joint Report Mr Willows expressed a contrary opinion based on his temporary finding that RW1 was covered by a 'facing' layer, but he retracted that opinion during the hearing.
7. The overwhelming evidence is that RW1 is not fit for purpose. Its condition is so poor that it requires significant work to repair or replace it, not in parts but in its entirety. It seems that trees T1-T4 have caused some localised damage such as cracking of the wall near each tree, but the principal cause of the wall's condition is that its design and construction were inadequate for its purpose.

Acts or omissions by the applicant

1. In determining appropriate orders, it is relevant to consider the applicants' acts or omissions that might have contributed to the situation: The Owners - Strata Plan 3346 v The Owners - Strata Plan 10848 [2021] NSWLEC 1504 at [18]-[24]. Significantly in these proceedings I note that the applicants first became aware of damage to RW1 in 2000. In Ms Gowland's affidavit of 30 April 2021 (Exhibit B) she stated at paragraphs 16 and 17: "16. My husband and I first became aware of large cracks in RW1 near to a eucalypt and a black bean tree located on 10 [street address] in 2000 after being informed by the then owner of 10 [street address], Dennis Hatton. 17. Mr Hatton showed us large cracks in RW1 adjacent to the eucalypt and black bean trees located on 10 [street address]."
2. The respondents purchased their property in August 2013. At paragraphs 25-27 of her affidavit, Ms Gowland stated: "25. From 2013 to 2019, my husband and I had a cordial relationship with the Respondents, including co-operating in trimming joint hedges and allowing them to access to our driveway to remove a large camphor laurel tree. 26. We approached the Respondents in early 2018 about replacing RW1. We had a survey conducted of our driveway and RW1 by Bee & Lethbridge (Tab 16). 27. This survey identified that RW1 was (now) partly on No 10 [street address]."
3. The statements above show that the applicants were aware of damage to RW1 in 2000 - not just minor damage, but "large cracks". They did not resolve the issue with the then owners of the respondents' property. They first raised the issue with the respondents in 2018, almost five years after the respondents purchased their property.

Other causes of damage

1. The first relevant matter above to consider more closely is that of causation. While trees T1-T4 have caused some damage, it is not that damage that gives rise to the need to replace or repair the entire retaining wall RW1.
2. In Riggio v The Estate of the late Phyllis Annette Lockard [2011] NSWLEC 1292 at [40], Commissioner Fakes discussed a retaining wall that was partly damaged by trees. "40 I consider that while the physical pressure of the roots of Trees 3 and 4 has contributed to the displacement of the wall in their immediate vicinity, it is the age and construction of the wall, in combination with the pressure of soil and water that are likely to have migrated down slope over the decades the wall has been in existence, that are the major factors contributing to its condition. I also find it difficult to accept the applicant's contention that the trees have pushed the entirety of the wall onto his property. It is difficult to understand how this could occur in such an even fashion along its length. A more likely explanation is that the wall was constructed on his property in the first place."
3. Fakes C went on to order some contribution be made to the wall's repair or replacement on this basis. However, the details of each application are particular to the situation. It might be reasonable for the respondents in these proceedings to contribute to the cost of works proportionally to the extent to which their trees have caused damage, but this is so minor compared to the overall condition of the wall due to other factors that I would not be minded to make such orders.
4. Perhaps more importantly, I return to Mr Doyle's submission regarding the Court's jurisdiction at s 9 of the Trees Act. Orders can be made to remedy, restrain or prevent damage to property caused by the trees. It seems to me that the Court's jurisdiction in these proceedings extends to the areas of localised damage near trees T1-T4 identified by the experts and discussed above, but possibly no further. Of course, the Court's aim should always be to grant remedies that, as far as possible, might resolve all matters in controversy between the parties (s 22 of the Land and Environment Court Act 1979) but this must be done within the jurisdiction of the relevant act and its intention. In tree disputes under the Trees Act, the Court has made orders to remedy damage to property partly damaged by trees, but to my mind the damage caused by trees must give rise in some way to the need for those works. Here, the works are required, even on the applicants' own evidence, whether or not the trees have caused any damage. If replacing the entire wall was not required, it may be appropriate to order that small sections near each tree be repaired. This would be pointless, however, when the wall is likely to be demolished and replaced.
5. Pursuant to s 13A of the Dividing Fences Act 1991 (the 'Dividing Fences Act'), the Court's jurisdiction extends beyond the section of a dividing fence damaged by a tree, allowing the Court to make orders under that act for the remainder of the fence even where it has not been damaged by the tree. However, a retaining wall, even where it is on a boundary, is only considered a fence in the Dividing Fences Act (at s 3) if the wall supports a fence. RW1 does not support a fence.
6. Considering the above, I find that the Court does not have the jurisdiction to make orders for RW1 beyond those sections damaged by trees T1-T4. Due to the applicants' evidence that the entire wall needs remedy, it would not be appropriate to make orders for repairing only those sections damaged by T1-T4, nor for contributing to the cost of remedying those sections of damage.

The applicants' acts or omissions

1. If I am wrong in my conclusions above, I am also disinclined to make orders for remedying RW1, or for contributing to its costs, for further reasons.
2. The second relevant matter at s 12 to consider more closely takes in the acts or omissions of the applicants. Damage to RW1 near the trees in 2000 was described as 'large cracks' by Ms Gowland. The respondents did not purchase the property until 13 years later, by which time it might be assumed that the extent of damage had increased. It was another five years before the applicants raised the issue with the respondents. That is, during the 21 years that the applicants have known about the damage, the respondents have only been aware of it for the last three years.
3. In Cincotta v Huang [2011] NSWLEC 1086, Senior Commissioner Moore (as his Honour then was) and Commissioner Fakes made orders for a former owner of the respondents' property in that matter to pay for tree pruning works and for property repair works. The former owner had been joined as a respondent in those proceedings.
4. In Moutia v Jarrett [2013] NSWLEC 1129 at [29], Fakes C and Galwey AC found at [27]-[29]: "27 We also note that the respondent owned the property for only two months or so before the applicant noticed the seepage. We agree with the respondent that the damage to the pipes, particularly the crushing of the pipes as noted by the plumber, would take some time to occur, much longer than two months. Therefore, the vast majority of the damage occurred prior to the respondent's ownership of his property and therefore the tree. 28 We agree with the respondent that it would be unreasonable for him to have to contribute anything towards the cost of the applicant's plumbing costs. 29 As noted in previous judgments, an application for compensation for damage to property can only be made against the owner of the tree at the time the damage occurred - see Thornberry & anor v Packer & anor [2010] NSWLEC 1069 at [5]. If a property has changed hands over the period which the damage is said to have occurred, an applicant may make an application against the current owner but the former owner may be joined in the proceedings - see Smith & Hannaford v Zhang & Zhou [2011] NSWLEC 29 and Cincotta v Huang & ors [2011] NSWLEC 1086. The applicant has not sought to join the previous owner of the property."
5. It would be unreasonable for the respondents in these proceedings to pay for remedying damage to RW1, even that damage found to be caused by T1-T4, when most of that damage occurred before their ownership of the property. The applicants have not sought to join former owners of the respondents' property. No orders will be made in these proceedings for the respondents to contribute to the costs of works to RW1.

Do trees need to be removed?

1. If RW1 is left as is, trees T1-T4 will continue to cause damage. Their removal would prevent this. However, considering the significant contribution of T2 to the local landscape and environment, its retention, if possible, is preferred. Mr Simington said as much, but submitted that there was no solution on the table that would allow for T2's retention. Similarly, the overwhelming evidence of the engineers was that, to construct a new retaining wall along the boundary, T1, T3 and T4 would need to be removed. Regarding T2, they wrote at paragraph 26 of their original joint report: "26. DB and PW are of the opinion that it is preferable that Tree 2 be removed due to its close proximity to the new wall. DB and PW consider that if Tree 2 was left in place there would be a risk of the continual growth of the tree causing damage to the retaining wall and driveway in the future. DW is of the opinion that Tree 2 does not need to be removed for construction of the proposed retaining wall, provided the owners accept the risk of possible future damage. DW notes that arborist advice can be obtained and the design detailed to manage the future risk of damage."
2. The preferred option for replacing RW1 is a soldier pile wall with concrete sleepers. Mr Willows suggested other options, including leaving RW1 as it is and replacing the applicants' driveway with a fully suspended driveway, but considering his earlier 2019 report where he found RW1 posed a high risk, I did not give much weight to these suggestions. During the hearing Mr Bliss and Mr Waugh qualified their written evidence, conceding that T2 could possibly be retained. Their written comments referred to the likelihood of damage to the bottom of the wall if roots grow against it. However, they said that the risk of future damage would be minimised if a retaining wall is constructed on piers, with pier locations determined prior to finalising design, and all parts of the retaining wall installed with clearance to T2's roots. This would allow a new retaining wall to be constructed on the boundary without removing T2.
3. For the reasons above, and wishing to reduce the issues in dispute between the neighbours, I will make orders for removing T1, T3 and T4, but not for removing T2. As is usual in these matters, the applicants have not caused the need for removing trees so tree removal will be at the respondents' expense. Should the parties later agree that T2 should be removed, an application for consent to remove it can be made to Council.

Several issues remain unresolved

1. The applicants and respondents agree on some issues in these proceedings, but not on others. The respondents' earlier proposal to the applicants included: removing the trees and RW2 at their own cost; and, allowing the applicants to rebuild RW1, but wholly on the applicants' land, remove soil from the respondents' land, with all approvals for and costs of those works to be met by the applicants.
2. Ideally, the orders made in these proceedings would settle all elements of this dispute, but I have not found the jurisdiction within the Trees Act to do so. The details of rebuilding RW1, potential removal of RW2, and contributions to the costs of the works - these issues remain unresolved here. The grounds for their dispute appear to rely on each party's opinion as to who the retaining wall benefits, and whose responsibility it is. It is hoped that they can resolve these issues without having to rely on further court action in another jurisdiction. It is common in matters involving retaining walls for the parties to refer to the Conveyancing Act, in particular s 177(2): (2) Accordingly, a person has a duty of care not to do anything on or in relation to land (the supporting land) that removes the support provided by the supporting land to any other land (the supported land).
3. Section 177 of the Conveyancing Act abolished the common law right to bring an action in nuisance in respect of the removal of supporting land (s 177(8)), establishing a duty of care in relation to the right of support for land for the common law purpose of negligence (s 177(1)). The duty of care extends to built structures only where they have replaced the support formerly provided by the supporting land (s 177(4)). While s 177 establishes the framework for negligence relating to supporting land, which can include retaining walls, on my reading it does not establish, nor attempt to establish, ownership of a retaining wall. In these proceedings, neither party, through their acts or omissions, has caused a loss by removing support for supported land, so the Conveyancing Act provides little assistance. RW1 was constructed by the owner of the applicants' land many years ago. That person is not a party to these proceedings. The applicants and respondents have each bought their properties with RW1 in existence, roughly on their common boundary. Regardless of the aims of its builder, RW1 now benefits both parties by retaining the applicants' raised level land and driveway, and by preventing the raised land slipping onto the respondents' property: see Yared v Glenhurst Gardens (2002) 10 BPR 19,485; [2002] NSWSC 11 at [107]. An upgrade to RW1 would perhaps benefit the applicants more than the respondents, as they require it to support traffic on their driveway. If I had found it appropriate to order works to RW1, apportioning approximately one third the cost of those works to the respondents would seem reasonable.
4. Similar to a dividing fence on a common boundary, it seems to me that RW1 is the property of the applicants and the respondents, requiring agreement between them for any actions to the wall. Unlike a fence, it does not fall within the jurisdiction of the Dividing Fences Act. I have also found, for reasons described above, that I should not make orders to remedy damage to the wall under the Trees Act.

Orders

1. Based on the foregoing, the Court orders: 1. The application to remove T1, T3 and T4 is granted; the remainder of the application is refused. 2. Within 30 days of the date of these orders, the respondents are to engage and pay for a suitably qualified arborist (minimum AQF level 3), with all appropriate insurances, to remove T1 (Black Bean), T3 (camellia) and T4 (camellia). The works must be done in accordance with the 2016 Safe Work Australia Guide to managing risks of tree trimming and removal work. 3. The respondents are to give the applicants 2 days' notice of the works. 4. The applicants are to allow all access necessary for the works to be completed during reasonable hours of the day. 5. The exhibits are returned, except for Exhibits A, B and 1.

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