Marking out a straight fence line before you start digging is one of the most important steps in any fencing job. Get it right and your fence will look professional and sit exactly where you want it; get it wrong and you could end up with a crooked fence — or worse, one that encroaches on your neighbour's property. Here's how to do it properly.
Confirm Your Boundary First
Before you mark anything, make sure you know exactly where your legal boundary sits. Never assume a fence, hedge, or garden edge marks the true boundary. Your property's legal boundaries are defined by survey pegs, which are typically small metal pins or wooden stakes set by a licensed cadastral surveyor.
- Check your Record of Title and survey plan (available from Land Information New Zealand or your solicitor).
- Look for existing survey pegs at the corners of your section — they may be buried just below the surface.
- If you can't locate pegs, engage a licensed cadastral surveyor to re-peg the boundary before you build. This is money well spent to avoid a costly dispute later.
For boundary fencing between neighbours, the Fencing Act 1978 sets out how costs and responsibilities are shared. It's worth familiarising yourself with this if you're building on a shared boundary.
Tools You'll Need
- Tape measure (at least 30 m for longer runs)
- Builder's line (also called a string line or bricklayer's line)
- Line pegs or timber stakes
- Hammer or mallet
- Spray paint or chalk (for marking the ground)
- Spirit level (optional, for checking level over short distances)
- 3-4-5 triangle method or a builder's square (for right-angle corners)
Step-by-Step: Marking a Straight Line
1. Identify Your Start and End Points
Locate the two endpoints of your fence run — usually boundary pegs or existing structures like a gate post or house corner. Drive a timber stake firmly into the ground at each end.
2. Run a String Line
Tie your builder's line tightly between the two end stakes, keeping it as taut as possible. A sagging line will give you a curved fence. Pull the line tight and tie it off at the same height at both ends — typically around 100–150 mm above ground level so it's easy to see but doesn't interfere with your work.
3. Check for Sag on Long Runs
On runs longer than about 10–15 metres, a string line can sag in the middle even when pulled tight. To fix this, drive an intermediate stake at the midpoint and support the line from below so it stays perfectly straight. Check by sighting along the line from one end — it should look like a single point.
4. Mark the Post Positions
Once your line is set, use a tape measure to mark each post position along the line. Standard post spacing in NZ is typically 1.8 m to 2.4 m centres, depending on your fence style, rail size, and wind exposure — check your fence manufacturer's or timber supplier's recommendations for your specific situation.
Mark each post position with a stake or spray paint on the ground directly below the string line. Drop a plumb bob or use a spirit level held vertically against the line to transfer the mark accurately to the ground.
5. Squaring a Corner (3-4-5 Method)
If your fence needs to turn a corner at 90°, use the 3-4-5 triangle method:
- From the corner peg, measure 3 m along one fence line and mark it.
- From the same corner peg, measure 4 m in the approximate direction of the new fence line and mark it.
- Adjust the second line until the diagonal distance between the two marks is exactly 5 m.
- The angle at the corner peg is now a true 90°.
For larger sections, you can scale this up — 6 m, 8 m, 10 m works just as well and gives greater accuracy.
Dealing with Slopes
On sloping ground, you have two main options:
| Method | Description | Best for |
|---|---|---|
| Stepped fence | Each panel drops in steps following the slope | Most NZ timber paling fences |
| Raked (parallel) fence | Rails and palings follow the slope continuously | Picket fences, some modern styles |
For a stepped fence, set your string line level using a line level or water level, then step down at each post. For a raked fence, simply follow the slope with your string line.
Setbacks and Building Consents
In many NZ councils, fences over 2.0 m in height require a building consent. Fences under 2.0 m are generally exempt under Schedule 1 of the Building Act 2004, but rules vary by zone and location — always confirm with your local council before you start. MBIE Building Performance has useful guidance on what requires consent.
Also check your district plan for any setback rules from the road boundary, particularly for front fences.
When to Call a Professional
If you're unsure about your boundary location, always get a surveyor involved before building — it's far cheaper than moving a fence after the fact. For longer fence runs, uneven terrain, retaining fence combinations, or if you simply want the job done right first time, a qualified fencer will have the tools and experience to mark out and install your fence accurately. You can find licensed local fencing contractors on tradedirectory.co.nz.
