In the past, many decks were built with 4×4 support posts (also called structural posts). But these can bow seriously, even if a deck is only 3 feet off the ground. For that reason, we strongly recommend that you use 6x6s instead, even if your building department does not demand them. And if a deck is over 10 feet tall, you should install bracing.
This article shows installing non-notched posts on top of concrete footings that rise above the ground, to support framing that has already been built on temporary supports.
[tip] Wait for the Concrete to Cure
Allow at least two days for the concrete to cure before drilling holes and installing a post. If you install the post the same day as you poured the concrete, the footing could crack.
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Mark the post’s corner on the footing.
1. The support post’s side should be flush with the outside of the beam or doubled header.
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Draw the outline.
Use a level to mark the post’s corners, then use a square or straightedge to mark its outline.
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Heavy-duty hammer drill.
You can try to drill holes in concrete with a standard 3/8-inch drill, but it will be very slow going. Save yourself time and energy by using a standard-voltage heavy-duty hammer drill like this one, which will bore down with ease.
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Sleeve anchors.
Use sleeve anchors of a size recommended for your post base. The packaging will tell you the size of the drill bit to use, as well as how deep to drill the holes.
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Mark for the hole.
2. Position the post base as shown with its inside area aligned with the pencil lines. Scribe a circle where the base’s lag screw will go.
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Drill the Hole.
Drill a hole of the recommended size, a half inch or so deeper than the sleeve anchor. Pull out most of the dust by lifting the drill bit quickly as you drill, two or more times.
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Tap the anchor in.
3. Reposition the post base, aligned with the layout lines, and tap a sleeve anchor down into the hole.
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Tighten the bolt.
Use a crescent wrench or a socket wrench to tighten the nut, which will cause the anchor’s sleeve to expand so that it grips the concrete firmly.
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Measure for post
4. Install a post cap, also called a post-to-beam connector, onto the beam or doubled joist above; use a level to be sure it is plumb with the post base.
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Tap in the post.
Measure the distance between the two hardware pieces, then subtract 1/16 inch or so to account for imperfect cuts.
Use a hand sledge to tap the 6×6 into place, check for plumb, and drive nails into all the hardware holes to secure the post.
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Finish with nails.
Use a hand sledge to tap the 6×6 into place, check for plumb, and drive nails into all the hardware holes to secure the post. With the posts in place, you can remove the temporary supports.