Post Caps

Post caps close off the open top of a steel or composite post. They keep water and debris out of the channel, which matters for the life of the post, and they give the top of the wall a finished edge instead of a raw section. On a galvanised post the coating protects the steel, but an open channel still collects water and leaf litter, and neither does the post any favours.

Matching the cap to the post

• H post cap for H posts, which have a channel on both sides of the web.
• C channel post cap for C posts, which have a channel on one side only. These sit at each end of a run.
• 90 degree post cap for square corners. These come left leaning and right leaning, so check which way your corner turns before you order. Getting this wrong is the most common mistake on this page.
• 45 degree post cap for splayed corners.
• Composite capping runs along the top sleeper rather than capping a post, giving a clean square edge across the whole wall. It is compatible with 100mm wide posts.
• Composite support doubles as a footing for your bottom sleeper, which adds stability while you are building.

How many

One cap per post, matched to that post's profile. On a straight run that means two C caps and the rest H caps. Add a corner cap for every corner post, with the correct lean on the 90 degree ones. Composite capping is ordered by the metre along the top of the wall rather than by the post.

Our wall calculator counts the caps with the rest of the take-off, so the number follows your post count automatically.

Worth knowing

Caps are a finishing item rather than a structural one, which is exactly why they get left off a materials list and then noticed the week after the wall goes up. They are cheap, and a second delivery for a handful of caps is not. If you are unsure which profile you have, send us a photo of the post top and we will tell you which cap it takes. The guide to choosing steel posts explains the C and H profiles if you want the background.