Are Vinyl Post Inserts Needed?

When do you need vinyl post inserts?

Throughout the entire residential fence industry, there are very few standards with the exception of some broad-based ASTM standards.  As a matter of fact, the uniform building code and civil codes do not regulate residential fencing at all. This lack of standards is no exception for the vinyl fence industry.  As a result, some DIY box store distributors and extruders have defaulted to thin-walled materials to maintain a competitive edge.  

Posts vs Rails & Pickets

In some instances, thinner-walled pickets and rails are acceptable as extruders have engineered the profiles with structural webbing and crimps.  However, vinyl posts remain an issue as these larger profiles do not easily accommodate additional webbing which results in a considerable amount of additional materials.  To compensate, these distributors are recommending homeowners insert wood or steel posts.  This is not a good solution as these materials do not insert well into these posts, not leaving enough room for rails and providing inconsistent results.  Even though the post support may support the post, it does not support where the vinyl post attaches to the vinyl rail, leaving a weak link and a concentrated point for wind loading to cause failure.  In addition, post inserts do nothing to compensate for the thin-walled vinyl that is prone to cracking and splitting.

The solution

Use quality coextruded vinyl posts with a minimum wall thickness of .140.  A coextruded post offers a thin UVB inhibitive outer coating and a thick inner structural layer designed to flex and not crack and split.  Though these posts are traditionally more expensive; these posts typically have long extended warranties.  These posts are not only designed to withstand high winds but provide consistent support for the post and post attachment to the rails, leaving no weak link. 

Bottom line, be wary if your distributor or contractor is offering you a post insert in lieu of a thick-walled coextrude vinyl post.  It has the appearance of being an upgrade with down gradable results.