Joining two fence sections at an angle is one of the trickier parts of a fencing project, but with the right approach it's very achievable for a capable DIYer. The key is getting your corner post set correctly and choosing the right joinery method for your fence style and the angle involved.
Understanding the Angle You're Working With
Before you pick up a tool, measure the angle between your two fence lines. Angles fall into a few broad categories:
- 90° (right angle) – the most common corner, straightforward to build
- Obtuse angles (greater than 90°) – common on sloping or irregular sections
- Acute angles (less than 90°) – trickier, and may need a specially sized post or a double-post solution
Use a bevel square or a digital angle finder to measure the exact angle on site. Don't assume — ground levels and boundary lines are rarely as tidy as a plan suggests.
Setting the Corner Post: The Foundation of a Good Join
The corner post is the most critical element. A poorly set post will cause the whole join to rack and fail over time.
Post sizing
For most residential timber fences in NZ, a 100 × 100 mm H5-treated timber post is the standard for corner and angle posts. The extra mass gives you more face area to fix rails into from two directions. For steel or aluminium fencing, use the manufacturer's specified corner post — these are usually a larger section or a purpose-made corner extrusion.
Setting depth and concrete
As a general guide, bury at least one-third of the post length in the ground, with a minimum of 600 mm for a standard 1.2 m fence and 750–900 mm for a 1.8 m fence. Set the post in concrete (a bagged rapid-set mix works well for DIY), sloping the top of the concrete collar away from the post to shed water. Allow the concrete to cure fully — typically 24–48 hours — before loading the post with rails.
Aligning the post to the angle
For anything other than a 90° corner, you have two main options:
- Single post, rails fixed to adjacent faces – Works well for angles between roughly 70° and 110°. Fix one fence rail to one face of the post, and the other fence rail to the adjacent face. The angle between the faces of a square post is 90°, so for angles close to 90° this is ideal. For other angles, you may need to cut a slight bevel on the rail ends so they sit flush.
- Double post – For acute or very obtuse angles, set two posts close together (one for each fence line) with a small gap between them. This gives each rail a clean, square fixing surface and avoids awkward bevel cuts.
Fixing Rails at an Angle
Once your post is set, you need to connect the horizontal rails from each fence section securely.
- Skew-nailing or screwing – Drive 100 mm galvanised or stainless-steel screws through the rail end at an angle into the post face. Use at least two fixings per rail end. Stainless steel is worth the extra cost near the coast.
- Rail brackets / joist hangers – Purpose-made galvanised rail brackets (available at Bunnings or Mitre 10) give a stronger, more consistent connection than skew-screwing alone. Some brackets are adjustable for non-90° angles.
- Through-bolting – For heavy-duty or structural applications, a M10 or M12 galvanised bolt through the post and rail gives excellent shear strength.
Fitting the Palings or Panels
Once rails are fixed, hang your palings or panels as normal on each fence run. At the corner itself:
- For paling fences, the last paling on each run will need to be ripped (cut lengthwise) to fit neatly against the post or the adjacent paling. A circular saw with a rip fence makes this straightforward.
- For pre-made panels, you'll almost always need to trim the panel at the angle. Measure carefully and cut with a circular saw. Seal any cut ends of treated timber immediately with an end-grain preservative to help protect the cut surface — note that end-grain sealing is good practice but does not fully restore the original treatment rating; check with your timber supplier for guidance.
- For aluminium or steel panel systems, check with the manufacturer — many have purpose-made angle connectors or adjustable corner posts that avoid the need for cutting.
Bracing for Strength
Angle joins and corner posts take more lateral load than mid-run posts. Consider adding a diagonal brace rail from the corner post back to the next post along each fence line, especially for taller fences or exposed, windy sites. This is standard good practice under NZ conditions and aligns with the principles in BRANZ guidance on timber fencing.
A Note on Treated Timber and NZ Standards
All timber in ground contact must be H5 treated; timber above ground but exposed to weather should be at least H3.2 treated. This is a requirement under the NZ Building Code and is important for durability in our climate. Check the MBIE Building Performance website for guidance on when a fence requires a building consent — most residential boundary fences under 2.5 m are exempt under Schedule 1 — but confirm the exact height threshold and any conditions with your local council, but always confirm with your local council before you start.
When to Call a Professional
If your angle join involves:
- A retaining wall or a fence on top of a retaining structure (which almost always requires consent and may need an engineer)
- Complex geometry across sloping ground
- Shared boundary fences where neighbour agreement is needed
- Any electrical fencing components (which must comply with WorkSafe NZ requirements — see WorkSafe NZ)
…it's well worth getting a qualified fencer involved. A professional will get the post alignment right first time and ensure the structure is built to last. You can find experienced local fencers on tradedirectory.co.nz.
