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Expert Advice • 27 Jan 2026

Do You Need a Survey Before Building a Fence in Sydney?

Surveyor measuring fence line

Quick Answer

Yes, highly recommended. While not strictly "legally required" for every single fence, building without a survey leaves you liable for encroachment. If you build on your neighbour's land, you may be forced to tear it down at your own cost. A Boundary Identification Survey costs a fraction of the price of a legal dispute.

You're about to build a new fence. You and your neighbour have agreed on the style and cost. But do you know exactly where the boundary line is?

Old fences are rarely on the exact legal boundary. In Sydney, we frequently see fences that are 10cm to 50cm off the line. Over a 30-meter boundary, that adds up to a significant amount of land value lost or gained incorrectly.

The Legal Position in NSW

The Dividing Fences Act 1991 (NSW) governs fence construction. Here is what you need to know:

  • No Survey Required? Strictly speaking, the act doesn't mandate a survey if owners agree.
  • You Are Responsible: If you build the fence in the wrong spot, you are liable.
  • Adverse Possession: Just because an old fence has been there for 20 years doesn't mean that's the new boundary.

3 Reasons to Survey First

We recommend a Boundary Identification Survey for three simple reasons:

  1. Peace of Mind: You build knowing 100% that the structure is on your land.
  2. Dispute Prevention: A signed plan from a registered surveyor is a legal document. It stops arguments before they start.
  3. Property Value: Ensuring you claim all the land you own maximizes your property value when you sell.

Frequently Asked Questions

Do I need a survey if replacing an old fence?
If you are replacing it in the exact same post holes, you generally don't need a new survey. However, if the old fence was leaning or you are moving the line, you should get a survey.
Is a boundary survey legally binding?
Yes. A survey plan signed by a Registered Land Surveyor is a legal document that defines the property boundaries and can be used in court if a dispute arises.
How much does a fence survey cost?
For a standard residential block in Sydney, a Boundary Identification Survey typically starts from $1,400 + GST. This includes marking the corners and providing a sketch plan.