Legislation cited: ACT Civil and Administrative Tribunal Act 2008 ss 7, 56, 79

Common Boundaries Act 1981 s 10

Encroachment of Buildings Act 1922 (NSW)

Encroachments Act 1944 (SA)

Encroachment of Buildings Act (NT)

Property Law Act 1974 (Qld)

Property Law Act 1969 (WA)

Subordinate

Legislation cited: Planning and Development Regulation 2008 Sch 1A, s 1A.10

Cases cited: Blackshaw & Evans v Campbell (No.2) [2016] ACAT 108

Brand v Chris Building Co Pty Ltd [1957] VicRp 91; [1957] VR 625

Campbell v Blackshaw & Evans [2017] ACAT 64

Campbell v Blackshaw & Evans [2018] ACTSC 39

Campbell v Blackshaw & Evans [2019] ACTCA 1

Excel Intelligent Pty Ltd v Thomson [2018] ACAT 4

Faull v Commissioner for Social Housing [2013] ACTSC 121

Giusida Pty Ltd v Commissioner for ACT Revenue [2016] ACTSC 275

Hill v Higgins [2012] NSWSC 270

In the Matter of AB [2018] ACAT 18

J&D Butland v M&J Cole [1995] NSWLEC 9

Williamson v Friend (1901) 1 SR (NSW) 23

List of

Texts/Papers cited: Warren Swain, Unjust enrichment and the Role of Legal History in England and Australia [2013] UNSWLawJl 41; (2013) 36(30) University of New South Wales Law Journal 1030

APPEAL TRIBUNAL: Presidential Member G McCarthy

1. The orders of the Original Tribunal made on 21 January 2019 are set aside.
2. Sim Hom Tam is removed as an appellant to this proceeding.
3. The appellant, at her own expense, construct a sandstone retaining wall on Block 4, Section 34, Lawson extending from the existing sandstone wall on Block 4, Section 34, Lawson, to a point where it abuts at right angles with the westernmost bluestone wall on Block 3, Section 34, Lawson. The construction work include all drainage and structural support work necessary to retain all soil on the respondent's land caused by any excavation (or cut) by the appellant on Block 4.
4. Upon completion of the work required by order 3, the respondent engage Lindsay Hicks Fencing and Maintenance to construct a Colorbond fence along the boundary between Blocks 3 and 4, 1.8m high, 'Monument' in colour and in a style to match the existing fence on the respondent's block PROVIDED THAT:
   • (a) the fence may, by agreement, be to a lesser height depending on the height of the sandstone retaining wall, to achieve a uniform distance not exceeding 1.8m between finished ground level on Ms Du's side of the retaining wall and the top of the fence along the entire length of the fence; and
   • (b) the appellant may at her discretion agree to construction of the fence on top of the existing sandstone wall and on top of the sandstone wall to be constructed under order 3.
5. The appellant and the respondent pay 50% each of the cost of constructing the fence described in order 4, including any costs relating to drainage, support and strengthening of the fence, PROVIDED THAT if the appellant agrees to construction of the fence on top of the existing and required sandstone wall per order 4:
   • (a) the respondent must obtain a quote from Lindsay Hicks Fencing and Maintenance to construct the fence on top of the existing and required sandstone wall; and
   • (b) if the cost of constructing the fence on top of the existing and required sandstone wall exceeds the cost of constructing the fence on the boundary, the respondent must pay any amount exceeding 50% of the cost of constructing the fence on the boundary.
6. The respondent provide the appellant with a copy of the final tax invoice for the fence constructed under order 4, and the appellant pay the respondent the amount determined under order 5 within four working days of receiving the tax invoice.

1. The appellant, Amanda Tam, lives at 17 Bellbird Loop, Lawson. Her house is on Block 4, Section 34, Lawson. Ms Tam is the (or a) Crown lessee of Block 4.[1]
2. The respondent, Xia Du, lives at 19 Bellbird Loop, Lawson. Her house is on adjoining Block 3, Section 34 Lawson, to the south of Block 4. Ms Du is the (or a) Crown lessee of Block 4.
3. Both blocks face onto Bellbird Loop on their western (front) boundaries. The land is sloped, running downwards from east to west.
4. Ms Tam and Ms Du have constructed discordant retaining walls between their respective properties.
5. Ms Tam has constructed a sandstone retaining wall commencing near the eastern (rear) boundary, extending towards the western (front) boundary.
6. Mr Milburn, a registered surveyor, provided a survey dated 4 October 2018 (the Survey) that records that a small portion of the sandstone wall that was visible towards the rear of the block encroaches onto Block 3 by 0.115m. The Survey states "only the visible wall has been surveyed, wall below ground level not surveyed." Mr Milburn's survey shows that the remainder of the sandstone wall, moving westwards, is approximately 0.02m clear of the boundary above ground level. He also notes "no provision made for fence posts on top of sandstone wall."
7. Mr Milburn provided an updated survey dated 12 December 2018 (the Updated Survey) regarding the encroachment of the sandstone wall. He states that "the wall about 0.20m below ground level encroaches onto Block 3 up to 0.18m where visible."[2]
8. By reference to an engineering design prepared by Mr Van der Veen regarding how the sandstone wall is (or should have been) constructed, Ms Du contended that 2m or more below ground level the footings of the sandstone wall encroach onto her land by 600mm.
9. Approximately 46.5m from the eastern (rear) boundary, Ms Tam's sandstone wall abuts a bluestone wall constructed by Ms Du (the Abutment Point). The bluestone wall continues westwards approximately along the boundary between the two blocks towards the front of the blocks before turning at a right angle (the Corner) to continue southward into Ms Du's block in order to construct (or retain) a terrace outdoor area on her block. A photo of the walls tendered in evidence in the initial proceeding shows a water tap at the Corner.[3]
10. Mr Milburn's Survey and the Updated Survey record that Ms Du's bluestone wall, from the Abutment Point to the Corner, encroached (at the time) onto Ms Tam's property by 0.17m.
11. Further along the boundary between Blocks 3 and 4, Ms Du has constructed a second bluestone wall running at a right angle from the boundary southwards into her land, presumably to create what will become a second lower terrace. The westernmost end of that second wall (the Western End) encroaches onto Ms Tam's land by 0.17m.
12. Nothing is constructed on the boundary between Blocks 3 and 4 between the Corner and the Western End. For safety and security reasons, a temporary fence has been erected across this portion of the boundary. Both parties want an additional piece of retaining wall over that length.
13. From the Western End, moving westwards along the boundary between the two blocks towards the front boundary, Ms Du has constructed a dark coloured metal fence.[4] That metal fence is clear of the boundary, and does not encroach onto Ms Tam's land.
14. The parties fell into dispute about how to address the mutual encroachments of their walls, what kind of retaining wall ought to be built between the Corner and the Western End and who should pay for it, and about the kind, height, colour and location of additional fencing required along their common boundary.
15. Ms Du filed an application in the Tribunal for an order under the Common Boundaries Act 1981 seeking an order that the parties construct a Colorbond fence, 46.5m long and 1.8m high, along the common boundary running from the eastern (rear) boundary to the Western End. Ms Du wanted the Colorbond fence to be erected on top of the sandstone wall. Ms Tam wants it on the boundary.[5]
16. Ms Du also wanted, for understandable safety and security reasons, a retaining wall to be constructed over the distance from the Corner to the Western End. This proposed wall, she said, has been approved by the ACT Planning and Land Authority (ACTPLA) as part of an approved development plan for works on Ms Tam's property.
17. Ms Tam would not agree to the construction of a fence until the issue of the encroachment of the bluestone retaining walls had been addressed.
18. There was also a dispute about the colour of the proposed fence. Ms Tam wanted the fence to be 'Windspray' in colour. Ms Du wanted it to be 'Monument' in colour. On 22 November 2018, after noting that Ms Tam had not completed any fencing on her property, the Original Tribunal determined that the fence be 'Monument' in colour to match the colour of existing fences on Ms Du's property.[6]
19. On 14 December 2018,[7] consequent upon irreconcilable differences between the parties, the Original Tribunal issued orders requiring Ms Tam and Ms Du to rectify the encroachments of their respective walls and to construct a Colorbond fence on the boundary.
20. On 21 January 2019, the Original Tribunal made an order, varying the dates by which Ms Tam and Ms Du were to rectify the encroachments of their respective walls. The orders made on 21 January 2019 that are now under appeal were, in substance, as follows:
    • (1) Ms Tam[8] "remove, alter or reconstruct" the existing sandstone retaining wall constructed by her "so as to ensure that no part of the retaining wall encroaches above or below ground level upon any part of [Ms Du's] block."
    • (2) Ms Tam, at her own expense, complete all retaining walls, including drainage work in accordance with the development approval in relation to their construction. The work include retaining walls and drainage work necessary to retain the excavation cut by Ms Tam and Sim Hom Tam during the construction of their house.
    • (3) Ms Tam bear all costs of the work to be done under orders 1 and 2.
    • (4) Ms Du has leave to relist the matter on 24 hours' notice should Ms Tam not comply with orders 1 and 2.
    • (5) Ms Du "remove, alter or reconstruct" the existing bluestone retaining wall "constructed by her so as to ensure that no part of the retaining wall encroaches above or below ground level upon any part of [Ms Tam's] block."
    • (6) Ms Du bear all costs of the work to be done under order 5.
    • (7) Upon completion of the work required by orders 1, 2 and 5, Ms Du engage Lindsay Hicks Fencing and Maintenance to construct a Colorbond fence along the boundary between Blocks 3 and 4, 1.8m high, 'Monument' in colour and in a style to match the existing fence on Ms Du's block.
    • (8) Ms Tam and Ms Du pay 50% each of the fencing costs, including any costs relating to drainage, support and strengthening of the fence.
    • (9) Ms Du provide Ms Tam with a copy of the final tax invoice for the Colorbond fence, and Ms Tam pay Ms Du 50% of the total invoiced cost within four working days of receiving the tax invoice.
21. The Original Tribunal provided reasons for its decision dated 22 March 2019. On 30 May 2019, I stayed the orders made on 21 January 2019 until further order.

1. An applicant may appeal to the Appeal Tribunal "on a question of fact or law."[9] By reference to this phrase, an applicant on appeal must show an error of fact or law in the decision under appeal and that the error affected the result.[10]
2. On the appeal, Mr Barrington-Smith appeared for Ms Tam. Ms Baker appeared for Ms Du. Mr Barrington-Smith alleged two errors of fact, three errors of law and four errors that he described as "discretionary errors."
3. The alleged errors of fact were as follows:
   1. Mistaken conclusions about the conduct of the parties in negotiations concerning the fence and inferences drawn.
   2. Concluding that there was no evidence as to a development application or approved plans.
4. The alleged errors of law were as follows:
   1. The misapplication of section 7 of the ACAT Act created issues of procedural fairness.
   2. The scope of section 56 of the ACAT Act and the powers granted under the Common Boundaries Act 1981 (ACT).
   3. Jurisdictional error via a failure to provide finality to the dispute.
5. The alleged discretionary errors were as follows:
   1. A denial of procedural fairness in pre-hearing procedures and inferences drawn.
   2. A denial of procedural fairness, and contravention of section 30 of the ACAT Act, in denying the Applicants the right to be represented in the manner elected and inferences drawn concerning delay
   3. A denial of procedural fairness, reliance on irrelevant matters and a failure to rely on relevant matters through the acceptance and refusal of parties' submissions.
   4. A denial of procedural fairness and consideration of irrelevant matters through adducing submissions and evidence in the absence of the Applicants.
6. I regret to say that I found all the alleged errors, on their face, to be meaningless.
7. Ground 1 does not state what conclusions the Original Tribunal drew about the conduct of the parties or how it affected the orders made concerning the fence. What inferences were drawn, or who drew them, or how they affected the result is also unknown.
8. Ground 2 appears to be factually wrong because the Original Tribunal referred to Ms Tam's evidence about the development application,[11] which I presume to mean the development approval for construction of her home which would necessarily have included approved plans. Also, there is no indication as to how the evidence about the development application affected the result.
9. Ground 3 refers to section 7 of the ACT Administrative and Civil Tribunal Act 2008 (the ACAT Act), which requires the Tribunal to ensure that its procedures "are as simple, quick, inexpensive and informal as is consistent with achieving justice", but also that it "observe natural justice and procedural fairness". Ground 3 says nothing about how or why the Original Tribunal misapplied section 7 or how the alleged misapplication "created issues of procedural fairness."
10. Ground 4 refers to section 56 of the ACAT Act, which describes different kinds of orders that the Tribunal may make. Ground 4 also refers to unstated powers granted, presumably to the Tribunal, under the Common Boundaries Act 1981. However ground 4 does not identify what orders the Original Tribunal made, or did not make, pursuant to those powers or why it erred in doing so or not doing so.
11. Ground 5 alleges a failure to provide finality to the dispute, but does not identify anything that remained to be decided.
12. Grounds 6, 7, 8 and 9 all allege a denial of procedural fairness, but none of the grounds states any fact or circumstance giving rise to that denial or indicates how it affected the result.
13. The only detail regarding a denial of procedural fairness appears to be the Original Tribunal "adducing" submissions and evidence from Ms Du in the absence of Ms Tam. I was prepared to presume Mr Barrington-Smith intended to say that Ms Du, not the Original Tribunal, adduced (further) submissions and evidence and that the Original Tribunal denied Ms Tam procedural fairness by accepting them in the absence of Ms Tam, but ground 9 still does not state what the submissions or evidence were or indicate how their acceptance affected the result.
14. At hearing, Mr Barrington-Smith explained that ground 9 involved a complaint that the Original Tribunal accepted further submissions from Ms Du, but rejected further submissions from Ms Tam. However, the alleged error fell away upon Mr Barrington-Smith accepting that "we're left guessing largely"[12] as to which submissions were accepted and not accepted. Mr Barrington-Smith stated that "the only concrete proof" about acceptance or otherwise of Ms Du's submissions was a reference to the fencing contractor named in order 7 of the Original Tribunal's orders, but that had no consequence upon Mr Barrington-Smith stating "that we don't take particular issue with who the fencing contractor is, provided that the job is done as required."[13]
15. Mr Barrington-Smith provided a 16 page document, single spaced, entitled "Amended reasons for appeal" providing further detail in relation to each of the nine alleged errors. I carefully considered the document, but regret to say that it did not shine any light on why the Original Tribunal erred in relation to any of grounds 1, 2, 3, 6, 7, 8, or 9 in a way that affected the result.
16. The document assisted me only in relation to grounds 4 and 5.
17. Ground 4, the document revealed, entailed a submission that the Original Tribunal did not have power under the Common Boundaries Act 1981 to order either party to rectify the respective encroachments of their walls, and that the Original Tribunal's "incidental power" under section 56 of the ACAT Act did not otherwise give it that power. However, Mr Barrington-Smith appeared not to press that ground upon acknowledging that the Tribunal has power to make orders requiring a person to rectify an encroachment under the law of nuisance.[14]
18. Ground 5 fell away upon the document revealing that the alleged "jurisdictional error" was the Original Tribunal's refusal to accept Ms Tam's further submissions. I have real doubt about whether a failure to accept further submissions can constitute jurisdictional error, but even if that were so it was not of consequence because Mr Barrington-Smith could not point to anything in his non-accepted submissions that could, if accepted, have affected the result. Also, I could not envisage a means by which further submissions (regardless of what they contained) could have any bearing on why the Original Tribunal's orders did not achieve "finality to the dispute."
19. Of greatest concern about the appeal was that none of the alleged errors addressed the ongoing issues of concern to Ms Tam and Ms Du about their retaining walls or the necessary fence.
20. The circumstance placed me in a considerable dilemma. Where none of the alleged errors raised any question of substance, I was inclined to dismiss the appeal. However, that would have left Ms Tam and Ms Du in an ongoing circumstance of uncertainty regarding construction work, existing and proposed, on their common boundary.
21. Fortunately, in the course of the appeal hearing, Ms Tam and Ms Du made a number of sensible comments and practical suggestions which enabled me, I hope, to determine this appeal in a manner that will permit the parties to complete the necessary construction work on their boundary and with peace of mind about its lawfulness. I first note the areas of resolution.
22. Referring to order 5 of the Original Tribunal's orders, Ms Du has shaved her bluestone walls so that no part of them encroaches onto Ms Tam's land. I state for the record my view that Ms Du is entitled to keep her bluestone walls in their present form and to extend them within the boundaries of her land as she chooses.
23. With the bluestone wall shaved to the boundary, it is now possible to continue the sandstone wall westward along the common boundary from the Abutment Point to the Corner. This would involve the continued sandstone wall sitting parallel and presumably built up to the existing bluestone wall along the common boundary with each wall sited approximately on either side of the boundary line. As I understand it, Ms Du agreed to Ms Tam extending or continuing the sandstone wall in this way provided Ms Tam paid for it. Ms Tam agreed to pay for it. In my view, that is a sensible and balanced outcome, given the present circumstances. It gives Ms Tam the continuity of her sandstone wall from east to west with a clear (or even) line, as she seeks, but she needs to pay for it. I will make an order to that effect.
24. Ms Du also agreed that Ms Tam could further continue the sandstone wall from the Corner to the Western End in order to fill (or complete) the existing open area along the boundary provided Ms Tam paid for it. Ms Tam agreed.[15] In my view, this too was a sensible compromise. It enables Ms Tam to have a common sandstone wall along the whole of her common boundary as she seeks, but at her cost. I will make an order to that effect.
25. The continuation of the sandstone wall between the Corner and the Western End would be on Ms Tam's land and, I presume, would involve further excavation (or cut) on Ms Tam's land.[16] The continued sandstone wall would therefore need sufficient structural integrity to retain soil and vegetation on Ms Du's land. The construction work will necessarily involve:
    • (a) temporary excavation of soil on Ms Du's land in order to provide a clear workspace for construction of the continued sandstone wall;
    • (b) construction of footings that will, in part, permanently encroach onto Ms Du's land by up to approximately 600mm depending on the height of the wall and the level of excavation (or cut); and
    • (c) remedial earthworks to make good the excavation of soil on Ms Du's land in a manner to return Ms Du's land to natural ground level (or higher by agreement) which may be to the height of the continued sandstone wall.
26. All of this work including the encroachment of the footings onto Ms Du's land is contemplated in the order I will make that Ms Tam construct the continued sandstone wall between the Corner and the Western End at her cost. For reasons discussed below, in my view the necessary encroachment of the footings would be lawful.
27. Referring to order 7, Ms Du wished the Colorbond fence to be constructed by Lindsay Hicks Fencing and Maintenance. Ms Tam did not oppose that aspect of order 7,[17] or the colour or style of the proposed fence. I will order accordingly.
28. With these issues resolved, only two issues remained for determination:
    • (a) Arising from order 1, the extent, if any, to which Ms Tam should be required to rectify the encroachments of her sandstone wall, above and below ground level.
    • (b) Arising from order 7, the location of the proposed Colorbond fence.

1. Disputes between neighbours where a building or structure of one neighbour straddles or overhangs the boundary of the other so as to encroach onto the other's land have been occurring for more than a century. In New South Wales, Queensland, South Australia, Western Australia and the Northern Territory, resolution of these disputes is now dealt with under broadly similar legislation.[18] However in Victoria, Tasmania and the ACT, disputes of this kind remain to be determined under the common law. Regrettably, the common law in this area is complex and uncertain. It also explains why several jurisdictions have taken the general common law principles and distilled them into statute.
2. There are sound public interest reasons for legislation of this kind. In Clarke v Wilkie[19] the Supreme Court of South Australia, per Wells J said:

In my judgement, the [Encroachments Act 1944 (SA)] was plainly remedial and innovative in character, and was designed to set at rest the depressing, and often prolonged, disputes between neighbours over boundary lines and alleged encroachments that are both substantial and permanent. Such disputes are age-old and invariably, in the protagonists, cause intense emotion and the suspension of rational thought.

1. This case highlights why, in my view, the ACT should also consider legislating to provide an expedient means of resolving disputes of this kind in the Territory.
2. Nevertheless, in this case, I am obliged to apply the common law. It provides that a building or structure that encroaches onto the land of a neighbour belongs to the neighbour[20] who may occupy it and prevent its owner from occupying it. That of course has an artificial application in the case of underground foundations for a retaining wall.
3. The owner of the land (and in this case Ms Du) on whose land the encroaching structure stands may also demolish it.[21] However, recent judgments have disagreed with the concept of 'self-help' to remedy an encroachment. The more appropriate course is to seek a court order, by way of mandatory injunction, requiring the encroachment to be removed. However, remedies of that kind are discretionary. A court, exercising equitable principles, will grant or refuse an application for an order that a person remove a building or structure that encroaches onto a neighbour's land according to the circumstances of the encroachment. It will consider factors such as whether the encroachment is minor, whether it causes inconvenience and whether the encroachment was inadvertent. Where factors of that kind are present, a court will also look to whether compensation is a more appropriate remedy, rather than demolition.[22]
4. Turning to the facts in this case, Ms Tam explained that she was willing to 'shave' the existing sandstone wall to address any encroachments above ground level, but did not wish to address the likely encroachments below ground level. Her concern was that without the below ground structural support, the wall would collapse or be at risk of collapsing.
5. In defence of Ms Tam's position, Mr Barrington-Smith characterised the encroachments of the sandstone wall as "trivial".[23] He relied on a decision of the NSW Land and Environment Court in J&D Butland v M&J Cole[24] in which the Court considered four different encroachments between two residential properties. For many reasons, that decision did not assist. First, the decision concerned an application under the Encroachment of Buildings Act 1922 (NSW), not the common law. Second, the encroachments were all above ground. Third, the Court regarded three of the encroachments of between 5cm and 35cm as "so minor as to be trifling" but did not hold that view regarding an encroachment of a section of sandstone retaining wall "by variable distances ranging between 18cm to 65cm" (noting that the below ground encroachment in this case is approximately 600 mm) Fourth, regarding that encroachment in J&D Butland, the applicant's concern was about the risk of injury to themselves or other occupants on their land caused by a collapse of the wall rather than the encroachment.
6. Applying common law principles, doing the best I can, in my view a court would not require Ms Tam to rectify the encroachment or order to pay Ms Du compensation for it.
7. Above ground, the encroachment of approximately 0.18m where visible is so minor that, in my view, no court would order it to be rectified. I draw support for that view from a decision of the NSW Supreme Court, per Harrison J, in Hill v Higgins.[25] In that case, the Court considered a retaining wall that encroached onto a neighbour's land by between 3cm and 15cm with an average encroachment of approximately 5.5cm. The Court said:

The extent of the encroachment, and hence the trespass, by the wall is truly insignificant. It causes no readily discernible structural incursion onto Mr and Mrs Hill's property and did not in my opinion have any detectable, let alone adverse, impact upon Mr and Mrs Hill's exercise or enjoyment of his or her proprietary rights.[26]

1. It is commendable that Ms Tam is willing to shave the wall back to the boundary, but in my view that is not necessary.
2. Below ground, referring in particular to the foundations, I am not persuaded that support for a wall constructed 2m below natural ground level that encroaches onto Ms Du's land by 600mm, if that were to be established, is anything but a minor encroachment. In my view, no court would order it be rectified. Such rectification action would make it impossible for structures to be built safely and satisfactorily on a boundary. I took into account Ms Du's wish to plant along the boundary, particularly fruit trees, and her concern that the footings might interfere with their root structure, but no evidence was led to that effect and I respectfully doubt that footings 2m below the surface would have that consequence.
3. To address Ms Du's concerns about the future saleability of her property,[27] I also record my view that no reasonable prospective purchaser of Ms Du's property could or would have a proper basis for objecting to the encroachment, above or below ground level.
4. On reviewing the transcript of the hearing before the Original Tribunal, it is apparent that it ordered Ms Tam and Ms Du to address the encroachments of their respective retaining walls not because it thought that was a necessary action but because of the mutual disharmony between the parties. I can understand the Original Tribunal's response, but have nevertheless concluded that as a matter of legal principle, having regard to the minor encroachment of the sandstone wall (above ground and below ground), the Original Tribunal's order 1 should be set aside. I will order accordingly.
5. I should also record that any encroachments onto Ms Du's land of footings necessary to construct the additional lengths of sandstone wall from the Abutment Point to the Corner and from the Corner to the Western Edge should be treated in the same manner, provided that the footings encroach only to the extent that is structurally necessary to support the wall and to retain soil on Ms Du's land in a safe manner.

1. It is self-evident from the excavation work on Ms Tam's side of the existing sandstone wall and bluestone wall, in contrast to earthworks built up to or near the height of the walls on Ms Du's side of the retaining walls, that a fence needs to be constructed above the wall and the proposed sandstone walls for reasons of safety and to provide privacy and security between the two blocks.
2. The fence can be up to 1.8m in height, but may not need to be that high having regard to the existing and proposed retaining walls. 1.5m or less might be sufficient.[28] I will order that the fence be 1.8m high, with the proviso that it can, by agreement, be to a lesser height (depending on the height of the sandstone retaining wall) to achieve a uniform distance not exceeding 1.8m between finished ground level on Ms Du's side of the retaining wall and the top of the fence along the entire length of the fence.
3. The question to be determined is the location of the fence. Should it be on the boundary which would entail its construction on the edge of the existing and proposed sandstone retaining walls, or can it be at or near the centre of the walls even though this would involve a small encroachment onto Ms Tam's land?
4. The Original Tribunal ordered that the fence be constructed "upon the boundary line" primarily (as I understood it) because the parties could not agree upon the location of the fence and would not negotiate in good faith regarding its path. The Original Tribunal was also satisfied on the evidence that the fence could not be constructed on the boundary line without first addressing the encroachments.
5. Those circumstances no longer apply. Regarding negotiation, the parties, to their credit, approached the appeal in a co-operative manner seeking primarily some certainty about what is lawful and permissible in order to complete construction works to their mutual benefit. Regarding the encroachments, for the reasons given, the minor encroachment of the sandstone wall need not be addressed and the bluestone wall has been shaved.
6. There would appear to be two options regarding location of the fence.
7. The first is to construct the fence on the boundary line in accordance with the Original Tribunal's order 7(a). This would eliminate or minimise any encroachment, but placement of the fence on the edge or on the corner of the sandstone wall might give rise to difficulties in construction and possible damage to the wall.
8. The second is to construct the fence on top of the sandstone wall, after the wall has been completed along its full length. This may be a more structurally sound manner to construct the fence and perhaps more aesthetically pleasing, but would involve a minor encroachment onto Ms Tam's land to the extent that the fence is set back towards her land from the (southern) top edge of the wall facing Ms Du's land. This might also involve additional cost. Placement might not be at the centre of the wall, but only in from the southern top edge to the extent necessary for the fence to be constructed in a stable manner.
9. I have concluded that where the options are (i) to build on the boundary or (ii) to build in from the boundary towards Ms Tam's land, it is for Ms Tam to decide where the fence should be located. Ms Du could not properly complain about construction of the fence on the boundary or about its construction away from the boundary towards Ms Tam's land.
10. The only comment I make is that if construction of the fence on top of the existing and proposed sandstone wall would involve additional cost and Ms Tam agrees to construction of the fence on top of the wall, Ms Du should pay that additional cost to reflect the minor encroachment onto Ms Tam's land and that its location on top of the wall would be for Ms Du's benefit. It is a matter for them to discuss.
11. I should also note that section 1A.10(3)(a)(i) of schedule 1A to the Planning and Development Regulation 2008 provides a statutory horizontal "tolerance" of 50mm, meaning that neither party has a basis to object if the fence is constructed not more than 50mm horizontally from the boundary. This adds to my view that if Ms Tam agreed to construction of the fence on top of the wall between 50mm and 100mm in from the southern edge of the wall, the encroachment would be so minor that no rectification order would be made to rectify it.

1. Given the extent of agreement that now exists between Ms Tam and Ms Du and my conclusions regarding encroachments and about the location of the proposed fence, the better course is to set aside all the Original Tribunal's orders made on 21 January 2019 and to make orders in substitution that reflect the agreement of the parties and my conclusions about existing and future work. This will also address the difficulty that Sim Hom Tam is not a party to the appeal.

[1] In the initial proceeding, Sim Hom Tam was a second respondent, however the solicitor for Ms Tam, Mr Barrington-Smith, said that an order was made "excising Sim Hom Tam from proceedings": Transcript of proceedings 30 May 2019 page 2, lines 7-8. However, this is not clear, and so as a matter of caution I will order the removal of Sim Hom Tam as an appellant to this proceeding.

[2] Much unnecessary legal debate occurred about the admissibility of the updated survey. I determined it should be part of the evidence because it gave more objective, factual and uncontentious information about the encroachment of the sandstone wall - that being a key issue on the appeal.

[4] Exhibit R3 in the proceeding before the Original Tribunal

[5] Transcript of proceedings 30 May 2019 page 98, line 44

[6] Original Tribunal's reasons for decision, paragraph 12

[7] A copy of the orders was issued incorrectly dated 18 December 2018. The Tribunal Registry later re-issued orders correctly dated 14 December 2018

[8] The orders made on 21 January 2019 directed to Ms Tam were also directed to Sim Hom Tam. I have omitted that detail in the summary of the orders, noting that Sim Hom Tam is not a party to the appeal.

[9] ACT Civil and Administrative Tribunal Act 2008, section 79

[10] Giusida Pty Ltd v Commissioner for ACT Revenue [2016] ACTSC 275 at [29]-[39]; Excel Intelligent Pty Ltd v Thomson [2018] ACAT 4 at [46]-[55] cited with approval in In the Matter of AB [2018] ACAT 18 at [41]. See also Faull v Commissioner for Social Housing [2013] ACTSC 121 on the principles affecting an appeal on a question of law

[11] Tribunal's reasons for decision dated 22 March 2019, paragraph 22

[12] Transcript of proceedings 30 May 2019 page 53, line 31

[13] Transcript of proceedings 30 May 2019 page 54, lines 5-7

[14] Blackshaw & Evans v Campbell (No.2) [2016] ACAT 108; Campbell v Blackshaw & Evans [2017] ACAT 64; Campbell v Blackshaw & Evans [2018] ACTSC 39; Campbell v Blackshaw & Evans [2019] ACTCA 1

[15] Transcript of proceedings 30 May 2019 page 97, lines 1-19

[16] I refer to the photograph at exhibit R3 before the Original Tribunal, which shows that significant excavation works would be necessary on Ms Tam's land between the Corner and the Western Edge

[17] Transcript of proceedings 30 May 2019 page 104

[18] Encroachment of Buildings Act 1922 (NSW); Property Law Act 1974 (Qld); Encroachments Act 1944 (SA); Property Law Act 1969 (WA); and Encroachment of Buildings Act (NT)

[19] Clarke v Wilkie (1977) 17 SASR 135, 139

[20] Brand v Chris Building co Pty Ltd [1957] VicRp 91; [1957] VR 625

[21] Williamson v Friend (1901) 1 SR (NSW) 23

[22] See Warren Swain Unjust enrichment and the Role of Legal History in England and Australia [2013] UNSWLawJl 41; (2013) 36(30) University of New South Wales Law Journal 1030

[23] Transcript of proceedings 30 May 2019 page 48, line 28

[24] J&D Butland v M&J Cole [1995] NSWLEC 9

[25] Hill v Higgins [2012] NSWSC 270

[26] Hill v Higgins [2012] NSWSC 270 at [46]

[27] Transcript of proceedings 30 May 2019 page 76, lines 12-21

[28] Transcript of proceedings 30 May 2019 page 99, lines 32-44