Is My Fence on the Boundary Line? A Sydney Guide

Almost every fence replacement we quote starts from the same assumption: that the old fence marks the boundary. Most of the time it is close enough that nobody thinks about it again. Occasionally it is not, and the time to find that out is before the new posts go in the ground, not after.

A dividing fence and a surveyed boundary are two different things. One is a structure somebody built, often decades ago, on a day when finishing the job mattered more than millimetres. The other is a line defined by your title and the registered plan of your land. They are usually in roughly the same place. They are not the same thing, and a fence is never proof of where a boundary runs.

Why older Sydney fences drift off the line

Nothing sinister is usually going on. In the older suburbs a boundary fence has often been rebuilt three or four times, and each rebuild was set out off the one before it. Small errors compound:

• Rebuilt in the old holes. The quickest way to replace a fence is to work off what is already there, so whatever the previous builder did gets inherited.

• Set in a little to dodge old concrete. Old footings are hard to remove, so a new post sometimes goes beside the old one rather than through it. Do that down a long run and the fence quietly shifts.

• Set out by eye instead of from the corners. A run that starts from the wrong reference point looks straight and still finishes well off where it should be.

• Built to follow a structure. Where a garage wall, dwarf wall or retaining wall came first, the fence tends to follow the structure, not the title line.

• Rear and side boundaries nobody ever pegged. Backing onto a laneway, reserve, drainage easement or a battleaxe handle, there may never have been a visible mark to build to.

• Marks that disappeared. Corner pegs get buried under paving, driveways, garden beds and landscaping within a few years of a subdivision.

When it actually matters, and when it does not

Being honest about this matters: most replacements go straight back on the existing line by agreement, and no survey is needed or warranted. It is worth establishing the real boundary when:

• you and your neighbour disagree about where the fence should sit, or one of you has raised it

• the neighbour has recently had a survey done, or is building and their builder has set out from the surveyed line

• the existing fence visibly cuts a corner, dog-legs for no reason, or runs through or around a structure

• the fence forms part of a pool barrier, where compliance is assessed on the barrier itself

• there is no old fence to copy at all, which is the usual situation when fencing a new build or a freshly subdivided block

• the fence is going in with a level difference or a retaining wall in the mix, so the wall and the fence have to be resolved together

• the other side is council land, a laneway, an easement or a company-owned property rather than a neighbouring house

• you intend to build near the line later, since setbacks for a carport, garage, pool or extension are measured from the boundary and not from the fence

How to find out where the line actually runs

Start with your own documents

Your title and the deposited plan for your land show the registered dimensions of the block, and copies are obtainable through NSW Land Registry Services. That paperwork is useful for a sanity check: if a fence is clearly in the wrong place, the plan will usually show it. What it cannot do is tell you where the line sits on the ground today, because transferring dimensions from a plan to a real yard with real slopes and real structures is the surveying job itself.

Look for survey marks, but do not trust them blindly

Corner pins, pegs, nails in a kerb or marks cut into a path are sometimes still there, particularly on newer estates. Treat them as a clue rather than an answer. A mark can be from an old informal set-out, can have been knocked during landscaping, or can belong to a different boundary altogether. Building a fence off a peg whose origin nobody can vouch for just creates a confident mistake.

A registered surveyor is the only thing that settles it

An identification survey locates your boundaries on the ground, marks the corners, and reports whether fences or structures sit over the line. Surveyors in NSW are registered and regulated through the Board of Surveying and Spatial Information, and a surveyor's set-out is what a builder, a council or a tribunal will actually work from. Where there is a genuine disagreement with a neighbour, the survey is almost always the cheapest part of the argument, and far cheaper than building a fence twice.

If the fence turns out to be off the line

An out-of-position fence is common and is not automatically something that has to be put right. What happens next is a conversation, not a demolition. In practice there are three outcomes: you agree to rebuild on the existing line even though it is not exactly the boundary, you agree to shift the new fence onto the surveyed line, or you agree a compromise line that clears the structures in the way.

Whichever it is, get it in writing before anybody orders materials. The practical side of that conversation is covered in our guide to replacing a fence without upsetting your neighbour, and the formal process for dividing fences in NSW, including fencing notices and what happens when owners cannot agree, sits with NSW Fair Trading and is summarised in our guide to who pays for a dividing fence in NSW.

Two things are outside a fencing contractor's lane, and we will say so on site rather than guess. Long-standing occupation of land, encroachment claims and anything touching on possessory rights are legal questions for LawAccess NSW or a solicitor. And a structure of the neighbour's that crosses the line, such as a slab edge, a brick pier or a garage wall, changes the method as well as the line, because we cannot cut, underpin or fix into someone else's building without their agreement.

Posts, palings and the question of which side is yours

A dividing fence between two homes is generally a shared asset rather than one owner's property, which is why the question is almost never settled by pointing at the posts. Nominally the fence straddles the boundary and the posts are centred on it. In practice they get set to clear what is already there: an old footing, a paved edge, a tree root, a neighbour's garden bed built up against the line.

The same goes for which face gets the rails. On a shared boundary that is a preference to be agreed, not a rule, and the options for handling it are set out in our timber paling fence guide. The one thing worth insisting on is that neither side treats the fence as a structure to build off afterwards, because soil, screens and shade sails hung on a boundary fence are what pull it out of line again.

Getting it right on a replacement

The practical protection on a like-for-like replacement is to record the existing line before the old fence comes out. A stringline down the existing run, photographs, and a couple of measurements taken off something permanent such as a house corner or a driveway edge mean the new fence can be put back exactly where the old one was, even after the old posts and footings are gone. That matters more than people expect, because getting the old fence and its footings out is what destroys the only reference anyone had.

If a surveyor is coming, book them before the demolition rather than after. And when you are comparing quotes, ask each contractor which line they are working to and how they are setting out, alongside the other questions in our guide to getting a fencing quote in Sydney. A quote that says nothing about set-out is a quote that has assumed the old fence was right.

Frequently asked questions

Is my fence the legal boundary of my property?

No. A fence is a structure, and the boundary is a line defined by your title and the registered plan. They are often close together, but the fence is not evidence of the boundary and has no standing as one. Only a survey by a registered surveyor establishes where the line is on the ground.

Do I need a survey before replacing a fence?

Usually not. If you and your neighbour agree the existing fence is in the right place and you are putting a new one back on the same line, a survey adds cost for no benefit. It becomes worth doing when there is a disagreement, when there is no existing fence to work from, when the fence forms part of a pool barrier, or when something is going to be built near the line.

Who pays for a survey on a shared boundary?

That is a matter for the two owners to agree, in the same way the fence itself is. Where owners cannot agree on boundary fencing costs, the process under the Dividing Fences Act is the avenue, and NSW Fair Trading explains it. We do not advise on cost splits, and no contractor's opinion changes what the legislation says.

My neighbour says our fence is on their land. What should I do?

Do not agree to move anything, and do not refuse outright, until the line is actually established. Ask what the claim is based on, and whether there is a survey. If there is not, a survey is the sensible next step, and the result is the same for both of you. Keep the conversation in writing from that point, and treat any legal question about the land itself as one for LawAccess NSW or a solicitor.

Can a fence be installed exactly on a surveyed line?

Where a surveyor has marked the corners, yes, the run is set out directly from those marks. Where structures, old footings or a level difference sit in the way, the practical line gets agreed first, because a fence built hard against someone else's slab or wall creates a maintenance problem for both sides. Either way, it is a decision made before the holes are dug, not during.

If you are replacing a boundary fence anywhere across Sydney and you are not certain the old one was in the right place, we are happy to talk it through on site before anything comes down. You can see what is involved on our boundary fencing page, browse the full range on our fencing services page, or get in touch for a quote.