Post-and-wire fencing is the go-to boundary solution for lifestyle blocks across New Zealand — it's cost-effective, durable, and well-suited to our varied terrain and stock requirements. With the right preparation and materials, a confident DIYer can tackle a straightforward boundary run, though larger or more complex jobs are best left to a qualified fencer.
Plan Before You Dig
Before you touch a post driver, do your homework:
- Confirm your boundary. Check your certificate of title and survey plan. If there's any doubt about where the legal boundary sits, engage a licensed cadastral surveyor — fencing on the wrong line can be a costly dispute.
- Talk to your neighbour. Under the Fencing Act 1978, adjoining landowners generally share the cost of a sufficient fence. Serve a formal fencing notice if needed before starting work.
- Check for services. Contact Dial Before You Dig (0800 248 344) to locate any underground cables, pipes, or fibre lines along your fence line.
- Building consent. Most rural boundary fences are exempt from building consent under Schedule 1 of the Building Act, but always confirm with your local council before starting.
- Stock type. The number of wires, wire gauge, and spacing depend on what you're containing — cattle, sheep, deer, or horses all have different requirements.
Materials You'll Need
| Item | Typical Spec (as a guide) |
|---|---|
| Strainer posts | 150–200 mm diameter, H5 treated timber or steel |
| Line posts | 75–100 mm diameter, H5 treated timber |
| Stays/struts | H5 treated timber or steel |
| High-tensile wire | 2.5 mm HT wire is common (check with your supplier for the equivalent gauge designation) |
| Staples or clips | 40 mm galvanised fencing staples |
| Strainer assemblies | Inline strainers or ratchet strainers |
| Wire strainer tool | Tirfor or fencing pliers with built-in strainer |
You'll find fencing supplies at Mitre 10, Bunnings, and PlaceMakers. For rural-specific stock, a local farm supply store will often have better range and advice.
Step 1 — Set Your Strainer Posts
Strainer posts (also called end posts or corner posts) are the backbone of the fence — everything else is tensioned off them. Get these wrong and the whole fence will fail.
- Dig or bore holes at least 900 mm deep (deeper in soft or sandy soils — up to 1200 mm).
- Set posts in concrete or compact firmly with a rammer in stable clay soils. Concrete is recommended for strainers.
- Install a diagonal stay (strut) on the inside of each strainer, angled at roughly 45°, bearing against a buried foot block. For longer runs, use a box strainer (two posts with a horizontal rail and diagonal wire).
- Allow concrete to cure for at least 48 hours before tensioning wire.
Step 2 — Set Your Line Posts
- Space line posts 6–10 metres apart on flat ground. Reduce spacing on slopes, soft ground, or where stock pressure is high.
- Drive posts to a depth of at least 600 mm (750 mm on slopes or soft ground) using a post driver — manual, tractor-mounted, or hire a petrol-powered driver.
- Keep posts in a straight line using a string line or laser level between strainers.
- On undulating ground, intermediate strainer assemblies may be needed every 200–400 metres to maintain tension.
Step 3 — Run and Attach the Wire
- Unroll high-tensile wire carefully — it has significant stored energy and can spring dangerously. Wear heavy leather gloves and eye protection at all times.
- Attach the wire to the first strainer post using a figure-eight knot or a purpose-made wire anchor.
- Run the wire along the fence line, stapling loosely to each line post as you go. Do not drive staples fully home yet — leave them slightly proud so wire can slide during tensioning.
- For a standard sheep/cattle fence, run 7–8 wires: bottom wires closer together (100–150 mm) to prevent lamb or calf escape, wider spacing toward the top.
Step 4 — Tension the Wire
This is the most critical step. High-tensile wire must be tensioned correctly — too loose and stock will push through; over-tensioned and posts will lean or wire will snap.
- Attach an inline strainer or ratchet strainer to the far strainer post.
- Use a fencing pliers or wire strainer tool to pull tension gradually and evenly.
- Correct tension for 2.5 mm HT wire should be confirmed with the wire manufacturer's specifications — the wire should feel firm and ring when flicked, but not be bar-tight — the wire should feel firm and ring when flicked, but not be bar-tight.
- Once tensioned, drive staples fully home at line posts, leaving a small amount of play so wire can move slightly with temperature changes.
- Tie off securely at the strainer post.
Step 5 — Check and Finish
- Walk the full fence line and check every post is firm, all staples are secure, and wire is evenly tensioned.
- Cut any protruding wire ends flush and bend them back safely.
- Check gates align correctly if any have been installed.
Safety Notes
- High-tensile wire under tension is extremely dangerous. Never cut tensioned wire without releasing tension first.
- Always wear gloves, safety glasses, and steel-capped boots.
- Be aware of overhead power lines when using long posts or machinery. Contact your lines company if work is near lines.
- Review WorkSafe NZ guidance on rural work hazards.
When to Call a Professional
Post-and-wire fencing is not restricted work under NZ law, so homeowners can legally do it themselves. However, consider hiring a qualified fencer from tradedirectory.co.nz if:
- Your boundary runs over steep, rocky, or heavily undulating terrain.
- You're fencing for deer, horses, or other high-pressure stock that require specialist fence design.
- The run is long (several kilometres) and requires machinery and experience to complete efficiently.
- You're unsure about boundary location or neighbour obligations.
A professional fencer will work faster, have the right equipment, and can ensure the fence meets the standard required for your stock and terrain.
