Add a few more inches of gravel then concrete. The bottom of the concrete needs to be below frost depth so dig at least an additional 6 inches or so. Without concrete footings (and often a wood member inside posts) vinyl fencing is not all that strong.
How Deep Should a Fence Post be for Vinyl? Rule of thumb 30 inches works best with most PVC fence posts. Anything less than that is based on other factors like manufacturer design and installation specs. Post holes should be deep enough to hold 1/3 the length of your post plus 6 more inches for a gravel base. Vinyl Fence Post Holes
Aug 15 2010 A vinyl fence post is a support structure of your vinyl fence. The positioning of your vinyl fence post is essential to the durability of your vinyl fencing. Step 1 - Mark your Location. Determine the total span of your vinyl fence and calculate the amount of vinyl fence post that you need to install. Ideally you need to have one vinyl fence post placed every six …
Oct 23 2019 Oct 23 2019 If you're still intent on setting fence posts yourself rather than having a professional do it the key is in filling the hole only halfway up with concrete. Even though it seems this would result in less stability this is not the case. Instead you're depriving Jack Frost of a lip he can use to get a tighter grip on the concrete footing.