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( setting a post on concrete )
|Setting A Vinyl Post On A
This is one method, among many, to set a hollow vinyl post on a concrete pad or sidewalk. It could be used for fence posts, hand rail or porch columns. We have shorter posts for our fences for this purpose. Specify "above-ground" installation when ordering. There are also special deck mount type fittings, which are expensive and they are not discussed further here. On wood decks, you would have to use those.
Use the post as a template by positioning it exactly where you want it on the concrete surface. Draw the outline of the post on the concrete.
Mark the centers of 4 holes that are to be drilled into the concrete. Move in from each corner towards the center of the post 1/2 the width of the hole to be drilled. Add 1/8" to 1/4" for a margin of error.
Using a hammer drill, which can be rented from a local tool rental store, drill a minimum of 4" into the concrete. Use a 5/8" to 1" drill bit, if 1/2" steel rebar is to be used. Drill clear through the concrete on shallow pads. If you drill entirely through the concrete, plug the bottom with a wadded piece of plastic bag or other object to prepare for filling the hole with liquid hydraulic cement. Drill the holes carefully to keep them vertical. Also pull the drill bit out as you drill to avoid getting it stuck. There could be rebar or wire in the concrete that will bind up or break the bit. Drill slow.
|After all four holes are drilled,
cut the rebar to a length equal to the hole depth plus the distance from the bottom of the
post to the middle rail or half way up the post. The exact height is not critical, but
avoid passing any mid-routed holes on the post. On corner, end and gate posts, the rebar
should go all the way near the top, just below the top routed hole on most styles of
Test the post fit by inserting the rebar into the drilled holes and sliding the post over all four pieces. See if the post can be plumbed on all sides using a level. If not, remove the post and tap the rebar on the sides to straighten them until the post can be plumbed. If the post won't fit over the rebar, don't panic. You screwed up, but you can drill another hole for the offending rebar and fill the bad hole later.
|Next mix hydraulic cement to a thick consistancy. As thick
as you can and still pour it easily. DO NOT use it thin. Add cement or water until you get
it right. Pour all four holes completely full and insert the rebar immediately. Hydraulic
cement sets up in 10 minutes in warm temperatures. You must work quickly or you will have
to redrill the holes.
Slide the post over the rebar immediately so you can plumb it and adjust the rebar for a correct fit.
After the hydraulic cement gets hard, measure for your next post spacing. Repeat for the second post.
Next install your rails. You must plug the bottom rail ends so concrete will not flow into them. Allowing concrete into any rail could eventually cause that rail to sag from the weight. You will fill the post with a concrete mix of sand, gravel and cement up to the previously specified height. DO NOT use the expensive hydraulic cement for filling posts, although you could pour in a few inches at the bottom only just to hold the post in place. If so you will have to plug the sides of the bottom of the posts to keep it from pouring out. Use electrician's or plumber's putty for plugging by rolling it into long strips and wrapping the bottom of the post and concrete pad, filling the crack. If some oozes out, no big deal, you can clean it up later.
After the sections are assembled and plumb, fill the post with concrete mix. Use bagged pre-mix, which is available in 60 or 80 pound bags. Any will do, such as Sakrete. Fill the post to a point just below the routed hole as discussed previously. Water will get into the routed holes after installation from rain and you want the concrete to be up high enough so the water won't pool inside the post. If you fail at this, you could later drill a drain hole in the vinyl in an inconspicuous place to allow the water to drain, if necessary. These little pools could be great nesting for mosquitoes and may cause frost damage to the posts in winter.