How to Attach a Post Before Pouring a Concrete Slab Basement

Measure the height between the concrete footing and the ceiling joist or beam that the post will support. Check the post length to make sure it is the correct height.

Set the post vertically on top of the concrete footing. Raise the top cap of the post so that it sits directly under the beam it will support. Screw or hammer fasteners through the top cap's pre-drilled slots and directly into the beam.

Place a carpenter’s level vertically on the side of the post. Adjustment the post by tapping the base with a hammer or mallet until it is plum on all sides.

Equip a hammer drill with a 1/2-inch masonry bit. Measure from the drill bit tip 4 inches, using a tape measure, and wrap electrical or duct tape around the drill bit shaft so that you don't over-drill into the concrete footing.

Place the masonry bit tip through a pre-drilled slot in the post's base plate and drill into the concrete footing until you reach the tape. Lift the rotating bit up and down inside the hole to remove the concrete debris. Continue on to the hole on the opposite corner of the base plate and drill another hole, for a total of two holes.

Place a 1/2-inch masonry bolt into each hole and thread them in, using an adjustable wrench. Pour the concrete when you're ready.