Fence Post Caps
(4 Products)Fence post caps are protective covers that fit over the top of timber posts. They help prevent rainwater from soaking into the exposed end grain - a common entry point for rot and decay, even in treated wood. Without a cap, the post top is left open to the elements and tends to split or soften after a few seasons.
Understanding Post Caps
A post cap is a protective cover that fits on top of a timber fence post. It protects the most exposed part of the post (the flat, sawn end) from the elements.
That open grain at the top acts like a sponge, soaking up rainwater and morning dew. And when moisture gets in, especially during repeated cycles of wet and dry weather, it leads to splitting, swelling, and eventually rot. Even pressure-treated wood isn’t immune.
Left unprotected, post tops are usually the first part of a fence to fail. A well-fitted cap stops all that before it starts.
A good cap:
- Stops water soaking into end grain
- Reduces cracking and weather wear
- Blocks UV degradation
- Keeps insects out
- Looks clean and finished
Why You Shouldn't Skip Caps
One of the most common oversights in fencing is assuming that pressure-treated timber is waterproof. In reality, it’s water-resistant - not impervious.
The preservative treatment slows decay but doesn’t eliminate it. When the top of a fence post is left exposed, it remains vulnerable. Moisture collects, absorbs into the end grain, and sets the stage for long-term damage.
Posts that may appear sound at a glance can feel soft or hollow when tapped. Fence panels begin to lean, and it’s easy to blame wind or poor fixings - when the real problem is rot working its way down from the top. In many cases, lifting a neglected or poorly fitted cap reveals damp, softened timber underneath.
It’s a small oversight with costly consequences. And the fix (a well fitted, treated post cap) is simple, affordable, and effective.
Choosing Between Green and Brown Treated Timber
Green Treated Timber
- Has a greenish hue from the copper-based preservatives used in the pressure-treating process
- Often fades to a soft grey-green tone over time
- Commonly used in domestic gardens and landscaping
Brown Treated Timber
- Has an added brown dye or stain on top of the standard treatment
- Gives a richer, darker appearance that blends in better with soil, stone, decking, or log cabins
- Favoured in rural areas, parks, and older properties for a more “settled” aesthetic
We supply matching green and brown treated fence posts, so you can keep a consistent look from cap to ground.
Fitting Post Caps
What You’ll Need:
- Exterior wood glue, grab adhesive, or waterproof PVA
- Galvanised screws (optional)
- A drill with pilot bit
- Sandpaper (for old or weathered posts)
Step-by-Step:
- Dry Fit First: Place the cap on the post to check sizing. If it’s tight, sand the post top slightly.
- Apply Adhesive: Use a bead of exterior wood adhesive inside the cap rim or directly on the post top.
- Seat the Cap: Press it down firmly and check it's level (use a spirit level if needed).
- Secure with a Screw (Optional): Drill a pilot hole and drive one stainless or galvanised screw through the side or top of the cap.
- Seal if Required: If using raw timber caps, treat them with the same oil or sealant as the rest of the fence.
Signs It’s Time to Replace Old Post Caps
- Cap is loose or missing altogether
- Visible cracks or splits in the wood
- Water pooling on top of the cap
- Discolouration (black stains usually mean water ingress or fungal growth)
- Insect holes or soft wood underneath
Even if the post itself is still solid, replacing a few worn-out caps can add years to the structure.
Frequently Asked Fence Post Caps Questions
Do I Really Need Fence Post Caps, Or Are They Just For Looks?
A post cap protects the exposed top of a timber post, which is where water tends to soak in. Over time, that moisture causes splitting, rot, or softening - especially in winter when it freezes and expands. Even pressure-treated timber isn’t immune. A cap helps stop that damage before it starts.
Can I Add Caps To Posts After The Fence Is Built?
You can add them any time, as long as the post tops are still in good shape. Just make sure the surface is dry and clean before fitting. If the top is badly split or already soft, it’s worth trimming it down slightly or sealing it before capping.
How Are Post Caps Fixed In Place?
Most are glued on using exterior-grade adhesive or screwed down through the top or side. If you’re using screws, go for stainless or galvanised to prevent rust. Always fit caps when the timber is dry for a solid bond.
What Happens If I Don’t Use Caps At All?
You’ll probably be fine for a while, but over time, the post tops will start to split or rot. Once moisture gets in, it weakens the whole post - sometimes from the inside out. Caps are a small investment that can easily double the life of a timber fence.
Are All Post Caps Pressure-Treated?
Not necessarily. Some cheaper versions are just stained or surface-treated, which won’t last as long. It’s best to choose caps that are pressure-treated, especially if you’re installing them on new fencing. Ours are all pressure-treated to match either brown or green posts.
