Freight is calculated based on your location and order size.We'll contact you with a freight cost within 1 business day before processing payment.
The C post cap is the finishing detail that separates a professionally completed retaining wall from an unfinished one. Designed specifically for 100PFC (Parallel Flange Channel) C-channel end posts, this galvanised steel cap seals the open top of the post cavity against water ingress, debris, and corrosion, protecting your investment for the life of the wall.
End posts cop the worst of the weather. They're at the exposed ends of the wall, often in corners or against fences, where water runs off the top sleeper course and directly into the post cavity if it's left open. In 50 years of building retaining walls, I've replaced more end posts than middle posts, and almost every failure started at the top of an uncapped post.
Specified and supplied by the Retaining Walls Direct trade team. Last updated August 2026.
The 100PFC C-channel post is used at the ends of retaining wall runs and at changes in wall direction. Unlike the H-beam middle post which has sleepers sliding in from both sides, the C-channel end post captures sleepers on one side only, making it the structural termination point of the wall. This means it carries significant lateral load from the retained soil, particularly at the base. Protecting the top of this post from corrosion is critical to maintaining the structural integrity of the entire wall end.
| Post Type | Section Size | Compatible Cap |
|---|---|---|
| C-Channel End Post | 100PFC | ✅ This product |
| H-Beam Middle Post | 100UC | H Post Cap |
| 90° Corner Post | 100PFC | 90° Corner Post Cap |
| C-Channel End Post | 150PFC | Contact us for 150-series caps |
C post caps are tool-free to install. Once your end posts are cut to final height and the top sleeper course is in place, press the cap firmly over the post top. The friction fit is secure under normal conditions. For coastal, high-wind, or high-humidity environments, apply a small bead of construction adhesive inside the cap rim before fitting to create a permanent weatherproof seal.
Tip: Fit caps as the very last step of the installation, after all sleepers are placed and backfill is complete. Caps fitted during construction are frequently dislodged during compaction and backfilling operations.
The C post cap is shaped to fit the open C-channel profile of a 100PFC end post. The H post cap fits the square hollow section of a 100UC H-beam middle post. They are not interchangeable, each is profiled to the specific post section it covers. Check your post type before ordering.
Yes. Even if the post base is in the ground, the top of the post above the final sleeper course is exposed to the weather and should always be capped. The cut end of the post at the top is where galvanising is most compromised and where corrosion initiates fastest.
Count your end posts (C-channel 100PFC), typically two per straight wall run (one at each end), plus additional posts at any wall terminations or step-downs. Corner posts use a different cap profile, see the compatibility table above.
The 45° angle post uses the same 100PFC section as the end post, so this cap will fit the post top. However, the angle post top is typically cut at a compound angle on site, confirm the cut profile before ordering.
No, this cap is sized for 100PFC C-channel posts only. Contact our team for 150-series post cap availability.
C post caps ship Australia-wide via standard freight. Lightweight and easy to combine with your post, sleeper, and drainage order for a single delivery. Trade account pricing available for builders, landscapers, and civil contractors, contact our team for volume pricing.
