How it connects
Slides externally over the square vinyl post top with a snug friction slip fit, commonly bonded permanently using PVC/vinyl adhesive cement or silicone sealant.
Male and female halves
Female socket on the post cap mating over the male square end of the hollow vinyl fence post.
Usually connects to
- square vinyl fence post male end
- hollow PVC fence post top
Common sizes
- Standard square post profiles: 4" x 4" (true 4.0" vinyl post) and 5" x 5" (true 5.0" vinyl post), as well as nominal wood post adapter sizes (3.5"/3.625" and 4.5").
Where it is used
residential fencingdeck and porch railingsvinyl privacy fencingoutdoor perimeter fencing
Variations
- external pyramid post cap
- external gothic post cap
- external ball post cap
- flat external post cap
- solar post cap
How to recognise it
Recognized by a square downward-facing recess or collar/skirt on the cap base with an inner dimension matching standard vinyl fence post outside dimensions (e.g. 4x4 or 5x5 inches).
Often confused with
| Confused with | How to tell them apart |
|---|---|
| Internal vinyl post cap plug | Internal caps insert tabs or a male plug inside the hollow post profile, leaving the post top edges exposed, whereas female slip caps have an external perimeter skirt that drops over the outside. |
| PVC plumbing slip socket | Plumbing slip sockets are round cylindrical DWV/pressure pipe hubs conforming to ASTM D2466/D2665, rather than square profiles. |
Also called
external vinyl post cap socketslip-over post capfemale post cap collarexternal pyramid cap socket
Good to know
Unlike nominal lumber post caps sized for 3.5" or 5.5" wood posts, standard vinyl fence caps are molded to true square dimensions (typically 4.025" or 5.025" ID) to slip over hollow extruded vinyl fence posts.
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