The Wall Two Buildings Depend On

The Wall Two Buildings Depend On

General information for South Australian landowners only. This is not legal, building or engineering advice. Whether a wall is a party wall, what rights and duties attach to it, what notice is required, and what your proposal does to a neighbouring building are questions for an SA property lawyer, a building certifier and a structural engineer against your actual property and proposal. The governing legislation and the requirements under it are amended over time, so confirm the live position before you rely on anything here.

The one part you cannot decide about alone

Owners think about a boundary as a line with their property on one side. For most of a site that is a workable picture.

A shared wall breaks it. It is a single structure doing structural work for buildings in separate ownership, which means it is the one part of your building where "it's my property, I'll decide" is not the operative rule — and where the decision you want to make may require you to be standing on someone else's land to carry it out.

This is not a boundary dispute topic. It is a project topic, because the constraint bites at the point where owners are least willing to absorb delay: at demolition, at excavation, and at the start of construction.

This article is about how that shared structure is handled. It is not about retaining walls, which are their own subject: retaining walls, boundaries and sloping blocks. And it is not about where the boundary actually runs, which is the fence is not the boundary.

It is a defined thing, and it comes with a consent

Start with what the term actually means, because owners use it loosely and the legislation does not.

A party wall is defined as "a wall built to separate 2 or more buildings or a wall forming part of a building and built on the dividing line between adjoining premises for their common use", and the published summary states that a party wall cannot be built without the written consent of the adjoining owner, with notice describing the proposed wall to be served on them (source: Law Handbook SA — Building work affecting other land).

Read that consent requirement before anything else. It means the wall your scheme depends on may not be yours to create unilaterally — which is a very different starting point from a boundary you may build up to.

There is a further step that owners almost never have in their programme: the published summary states that the owners must then register easements of support in respect of the party wall with Land Services SA (source: Law Handbook SA — Building work affecting other land). So the arrangement is not only physical; it is meant to end up on the title.

On the ongoing position, the published summary is that building owners have both rights and responsibilities in respect of party walls (source: Law Handbook SA — Building work affecting other land). What those are on your wall, and who owns what, are questions for your SA property lawyer — this article does not resolve them.

Whether a particular wall is a party wall at all — as opposed to two walls built close together, or one wall wholly within one title — is a question of fact about your buildings, answered by a licensed surveyor on position and your lawyer on rights. Owners get this wrong in both directions, and the assumption is expensive either way.

What the framework gives the owner doing the work

Here is the part that surprises owners, and it surprises them because it is more generous than they expect.

The published material describes a building owner as having rights in respect of a party wall — including to make good, underpin or repair a defective party wall, and to pull down and rebuild a party wall that is defective or not strong enough for a proposed building (source: Law Handbook SA — Building work affecting other land).

And further: a building owner has a right to enter and remain on the adjoining owner's land or premises to carry out building work in relation to a party wall, provided written notice of the proposed date and time is given to the adjoining owner — with notice to be given as early as possible in an emergency (source: Law Handbook SA — Building work affecting other land).

Read that carefully before treating it as good news. It is a right that arrives attached to a procedure, and the procedure is the part that lands in your programme. Whether you have such a right on your project, and what you must do to exercise it, is for your SA property lawyer against your actual situation — but the shape is worth carrying: access to a neighbour's land for this work is a process with a notice step, not a conversation over the fence.

What the framework gives the neighbour

The same subject, from the other side, and this is the part that appears in programmes as delay.

Where building work affects the stability of other land or premises, the published position is that the building owner must serve on the owner of the affected land or premises a notice of intention to perform the work and of the nature of that work, a stated minimum period before the building work starts (source: Law Handbook SA — Building work affecting other land). The building owner is also described as having to take every precaution to protect the neighbouring land or premises, including any action required by the council (source: Law Handbook SA — Building work affecting other land).

This article states no notice periods — what applies to your work is for your lawyer and the relevant authority against your actual proposal, and requirements change. What matters for planning the job is that there is a period, it runs before work starts, and it is triggered by an effect on stability rather than by a boundary being crossed.

That trigger is the trap. Excavation for footings, underpinning, or removing a structure that is currently doing structural work can affect a neighbouring building without any part of your work sitting on their land. Whether your proposal has that effect is a structural engineer's question, and it is one worth asking before the programme is issued rather than after the excavator is booked — ground conditions bear on it directly: reactive clay and site classification.

Support is a right, which is why "my half" is not a plan

The idea owners most often arrive with is that they can demolish their side and leave the neighbour's standing.

Support between adjoining buildings is treated as its own subject, and as noted above the published summary describes owners registering easements of support in respect of a party wall with Land Services SA (source: Law Handbook SA — Building work affecting other land). SA has also published an older building advisory notice on easements of support for party walls, issued under legislation since replaced — useful for background, but confirm the current requirements rather than relying on it (source: PlanSA — Building advisory notice 08/02).

The concept is what matters here: a building can hold a right to be supported, which is a very different thing from a preference about how the wall looks. If that right exists in your situation, removing the support is not simply your decision about your structure — and what you may do instead is a legal and engineering question in combination, not either one alone.

For a project, this is a sequencing fact. A demolition plan that assumes a clean separation, and a demolition plan that includes temporary support, notice and a certifier's involvement, are different programmes with different costs. The general shape of taking a building down in Adelaide is in demolition approvals and disconnections, and where character provisions add a further layer, historic and character area demolition.

And if something ends up on their land

One related concept is worth naming so it is not confused with the above.

Where part of a structure — including below ground — crosses the boundary, the published material treats it as an encroachment, dealt with under its own legislation (source: Law Handbook SA — Encroaching buildings).

That is a different question from a shared wall. The cited material treats party wall questions and structures crossing a boundary as separate subjects with separate remedies, and owners run the two together. Which one you have is a question of fact — position from a licensed surveyor, consequences from your SA property lawyer.

What this means for the programme

Not a legal conclusion. A planning one.

• Establish the wall's status before design is fixed. Whether it is shared, and where it sits, changes what may be drawn — and it is a survey and legal question, not a site-visit impression.

• Get the effect-on-stability question answered early. The cited material describes an effect on stability as what brings the notice requirement into play, and whether your work has that effect is an engineer's answer.

• If notice is required, put the confirmed period on the programme as a real duration, before the trade is booked. It runs before work starts, which means it cannot be absorbed once work has started.

• Treat access to a neighbour's land as a process. Even where a right exists, it comes with a procedure — and where relations are already strained, the procedure is the whole of it.

• Do not assume goodwill will hold or that its absence is fatal. Both assumptions produce bad plans. Ask your lawyer which process applies and plan around it, rather than around the relationship.

Where the same neighbour also has a say in the planning process, that is a separate track running in parallel: what a neighbour's objection actually does. Keeping both straight — and keeping the sequence — is the job described in what a development manager actually does.

Frequently asked questions

Can I demolish the part of a shared wall on my side? Not as a general proposition. Support between adjoining buildings is its own subject, and what you may do turns on the facts and your documents. That is a question for your SA property lawyer with a structural engineer, before demolition is programmed.

Do I have to tell my neighbour before I start? Where work affects the stability of other land or premises, the published position describes a notice of intention served a stated period before work starts. Whether it applies to your work is for your lawyer and the relevant authority.

Can I go onto their land to do the work? The published material describes a right of entry in relation to party wall work, subject to written notice of the proposed date and time. What that means in your case is a legal question, and the procedure is the part to plan around.

Who pays to maintain it? The published summary describes building owners as having both rights and responsibilities in respect of party walls. How that applies to a particular cost is for your lawyer, against your title and documents.

My extension will excavate near the boundary but not touch their building. Whether it affects stability is an engineer's question, not a distance judgement — and the effect, not the boundary, is what the published material describes as the trigger.

Who decides what, and where Cyberate PM sits

• Whether a wall is a party wall, what rights attach, and what notice is owed — your SA property lawyer.

• Where the wall and the boundary actually sit — a licensed surveyor.

• Whether your work affects the stability of a neighbouring building, and what support it needs — a structural engineer.

• What the building rules require of the work — a building certifier.

• What the temporary works and sequence cost — a quantity surveyor (QS) or your builder.

Cyberate PM does none of those. We do not advise on rights, survey boundaries, or design structures. We work owner-side: we get the wall's status established before the design is fixed, get the effect-on-stability question to an engineer early enough that a notice period is a programme line rather than a stoppage, and hold the sequence so demolition does not arrive at a wall nobody has resolved. What that role covers is set out in what a development manager actually does.

Before you programme demolition or excavation

• Is this wall shared — confirmed by survey and by a lawyer, not by appearance?

• Does my work affect the stability of the neighbouring building?

• If it does, what notice is required, and is that period on the programme?

• Do I need access to their land, and what is the procedure for it?

• Has temporary support been designed, priced and sequenced?

• Is anything on my building, above or below ground, already over the line?

The wall is the one part of the building you cannot decide about alone. Find out what it is before you plan to remove it.

The governing legislation, notice requirements and building rules are amended over time, and published advisory material may have been issued under earlier legislation. Nothing here states what applies to your property. Confirm the current position with your own legal, engineering and certification advisers before acting. Reflects publicly available material as at August 2026.

Sources

• Law Handbook SA — Building work affecting other land

• Law Handbook SA — Encroaching buildings

• Law Handbook SA — Neighbours

• PlanSA — Building advisory notice 08/02: Easements of support for party walls