In order to offer my clients extremely sturdy and long-lasting fence posts and stairway terminal posts, I make them out of PVC filled with concrete.
While the photo here shows how I connect one of my concrete-filled posts to an existing concrete pad, more typically I dig footing holes to the appropriate size and depth, then place a couple of lengths of #4 rebar in the holes so that the steel extends 2 feet above grade. Then I fill the holes to grade with concrete. As this first pour sets, I assemble my post sleeves out of ¾-inch-thick PVC trim ripped to size. I fasten the sleeves together with screws, then carefully brace them in place around the rebar so that they are square and plumb (there’s no adjusting them later).
At this point, rails can be fastened to the hollow posts using pocket screws. If the rails will need to be fastened to the posts later, I’ll add 2x4 PT nailers inside the assemblies prior to the pour to hold the rail screws. The hollow PVC posts act as forms as I fill them with concrete, though it’s not necessary to fill them all the way to the top. Any screws driven through the PVC become embedded in concrete, and the rebar ties the two pours together. The result is an extremely solid concrete post that extends from below the frostline to 2 feet above grade. Simple or ornate, these posts just don’t wiggle, and they’ll never rot.
Don Alan is a deck builder in Chicago, Ill.