Whether attaching a gate post to a block wall or adding a wood component to another block structure, joining wooden posts to cement or cinder blocks requires the correct hardware and a few simple tricks. There are a number of concrete fasteners available for use in attaching wood to concrete. Some are more effective than others. By far the simplest and most effective in most cases is the concrete screw.
Align the wooden post with the cement block. For gate or other fence post installations, use a carpenter's level to check that the post is level, or plumb, from top to bottom. For horizontal installations, place the level on top of the post and adjust as needed. Check for and remove any obstructions that will keep the post from attaching flush to the wall. Mark the line of the wooden post on the cement blocks.
Lay the post flat on a pair of sawhorses. Mark a line down the middle of the post from top to bottom, using a chalk line. Measure from one end and mark the post every 16 inches. Drill a hole through the post with a ¼-inch bit on every mark. Install a 1-inch paddle bit and drill down into each of these pilot holes to a depth of 1 inch. This will serve as a countersink to allow the concrete screw to tighten to the cement blocks more efficiently.
Position the pilot-drilled post against the blocks. Drill through every pilot hole in the post with a 3/16-inch rotary mason's bit into the cement block to a depth of 1/8 inch. These marks will serve to position the pilot holes in the cement blocks.
Set the post aside and drill the holes out to a depth of 2 inches. Blow the dust from the holes.
Reposition the post and drive one tapcon-style concrete screw through each pilot hole in the post. Drive the screws in until the they reach the bottom of the 1-inch countersink hole and run the head flush with the bottom of that hole, using a cordless drill.