Attaching fence rails to timber posts correctly is one of the most important steps in building a fence that stays strong, straight, and looking good for years. The best method depends on your fence style, the timber you're using, and how much load the rails need to carry. Here's a practical guide to the most common and reliable approaches used by NZ fencers.
Choose the Right Timber First
Before you think about attachment methods, make sure your posts and rails are fit for purpose. In New Zealand's variable climate — from the wet West Coast to the UV-intense Northland — timber selection matters enormously.
- Posts should be H5-treated timber (e.g., radiata pine) for in-ground use, as required for ground contact under NZ building practice.
- Rails should be at least H3.2-treated for above-ground exterior use.
- Hardwoods like macrocarpa or kwila are naturally durable alternatives and are popular in NZ.
Always check treatment levels on the timber label or ask your supplier at Bunnings, Mitre 10, or PlaceMakers.
Method 1: Notching (Mortise or Housing Joint)
Notching is the traditional method and is still widely used by professional fencers. You cut a shallow rectangular recess (housing) into the post face, and the rail sits snugly inside it.
How to do it
- Mark the rail position on the post with a pencil and square.
- Use a circular saw or chisel to cut a notch roughly one-third of the post's depth — no deeper, or you'll weaken the post.
- Seat the rail into the notch and secure with galvanised or stainless steel nails or screws.
Pros and cons
- ✅ Very strong mechanical connection
- ✅ Keeps rails aligned and prevents twisting
- ✅ Neat, traditional appearance
- ❌ Time-consuming, requires accurate cutting
- ❌ Reduces post cross-section slightly
Method 2: Face-Fixing (Butt Joint with Fixings)
The simplest method: the rail butts up against the side of the post and is fixed directly with screws or nails.
- Use 75–90 mm galvanised or stainless steel screws (two per rail end, minimum) for a solid connection.
- Pre-drill to avoid splitting, especially near rail ends.
- This method works well for lighter paling fences and is fast to install.
Important: Always use hot-dipped galvanised or stainless steel fixings with treated timber. H3.2 and H5 treated timber contains preservatives that corrode plain steel and zinc-plated fixings rapidly. This is a common and costly mistake.
Method 3: Metal Rail Brackets
Pressed metal rail brackets (sometimes called rail hangers or fence rail clips) are a popular modern option available at most NZ hardware stores. They bolt or screw to the post face and cradle the rail.
Types available
- U-channel brackets — the rail slides into a U-shaped metal channel fixed to the post.
- Adjustable angle brackets — useful on sloped ground where rails run at an angle.
- Through-bolt rail connectors — for heavier post-and-rail fencing.
Pros and cons
- ✅ Fast to install, no cutting required
- ✅ Consistent rail height and alignment
- ✅ Good for DIYers without advanced carpentry skills
- ❌ Can look less tidy on feature fences
- ❌ Must be galvanised or stainless to resist corrosion
Method 4: Cleats (Timber Blocks)
Cleats are small blocks of timber screwed to the post, with the rail resting on top of or against them. This is a quick method often used for temporary or rural fencing.
- Use offcuts of treated timber, at least 40 × 40 mm.
- Fix cleats with two screws per cleat into the post.
- Rest or nail the rail onto the cleat.
Cleats are less robust than notching or brackets for high-traffic or structural fences, but they're handy for garden or paddock fencing.
Spacing and Layout Tips
| Fence Type | Typical Rail Spacing | Number of Rails |
|---|---|---|
| Standard paling fence (1.2–1.5 m) | Top and bottom | 2 |
| Tall privacy fence (1.8 m) | Top, mid, bottom | 3 |
| Post-and-rail (farm/rural) | Evenly spaced | 2–4 |
| Picket fence (1.0 m) | Top and bottom | 2 |
- Position the top rail 100–150 mm from the top of the fence.
- Position the bottom rail 150–200 mm from ground level to allow airflow and reduce moisture contact.
Do You Need a Building Consent?
In most cases, residential boundary fences under 2.0 metres in height are exempt from building consent under Schedule 1 of the Building Act 2004 — but this depends on location, proximity to boundaries, and your local council's rules. Always check with your local council before starting. You can find general guidance at MBIE Building Performance.
Finishing and Maintenance
- Seal any cut ends of treated timber with an end-grain preservative — cutting exposes untreated wood.
- Consider painting or staining rails with a quality exterior timber stain from Resene or Dulux to extend service life.
- Check fixings and rail connections every couple of years, especially after wet winters.
When to Call a Professional
Fencing is generally DIY-friendly, but there are times when it pays to bring in a qualified fencer:
- Retaining walls combined with fencing — if the fence sits on or near a retaining wall over 1.5 m, engineering input and consent may be required.
- Sloped or difficult ground — getting rails level and posts plumb on a slope takes experience.
- Large projects or tight timelines — a professional fencer will work faster and often source better materials.
- Boundary disputes — a fencer experienced in NZ law can help navigate the Fencing Act 1978.
You can find qualified local fencers on tradedirectory.co.nz.
