Inside the post or over the outside?
| Cap arrangement | Measure on the mating post |
|---|---|
| Internal insert | Opening dimensions, profile and wall thickness; note any internal obstruction |
| External cover | Outside dimensions of the finished post and the shape of its corners |
| Mechanically retained cap | The relevant fit dimensions plus hole positions or other retaining features |
Cap selection starts with the finished post. Wall thickness, seams, corner radii and coating can change fit even when the outside trade size remains the same. For a rectangular section, record both dimensions. A single trade size can conceal a different profile or fit convention. The post specification and cap reference should use the same drawing or measurement basis.
Why wall thickness changes an insert fit
Consider an ideal rectangular post with outside dimensions of 60 × 40 mm and a uniform 2 mm wall. Its calculated inside dimensions are 60 − 2 × 2 = 56 mm and 40 − 2 × 2 = 36 mm. Increasing the wall thickness makes that opening smaller even though the outside size stays the same.
This is a dimensional example, not a cap size recommendation. Corner radii, weld seams, coatings and manufacturing tolerances affect the actual fit. The cap's retaining ribs or fasteners also need room to engage; the calculated opening alone does not define the cap dimensions.
Order approved replacement caps and mixed sizes by post reference
For a replacement, the existing part code is useful when it identifies the exact component. Otherwise, measurements of the opening and a photograph of the retaining detail are more useful than a photograph of the fence from a distance. A trial fit on the intended post checks both seating and retention.
For mixed orders, list caps against the matching post reference, material, finish and quantity. Separate size labels help an installation team distinguish otherwise similar parts. FencingWise can include caps with the post package or quote them as identified replacement components.
Custom order specification: fence post caps
| Order detail | What to define with our team |
|---|---|
| Mating dimensions | Provide internal opening for inserts or finished outside dimensions for covers. |
| Cap construction | Identify profile, material, retaining ribs, clips or specified fasteners. |
| Batch identification | List cap-to-post references, colour or finish and quantities for each size. |
Agree a trial fit on the intended post where samples are requested, checking both seating and retention. Retain the approved component reference for the batch. Any sealing or drainage requirement must be separately specified rather than inferred from a fitted cap.
Can several cap sizes be supplied in one order?
Yes, list each cap with its post profile, fit dimensions and quantity. We review individual references and packing units so similar-looking sizes remain distinguishable on receipt.