How to Install a Doggy Door in Cinder Block

Place the supplied template on the outside of the cinder block wall, where you will make the opening. Tape the template in place and trace around it with a piece of chalk. Remove the template. Hold a yardstick diagonally across the template outline, from the upper-left corner to the bottom-right corner and make a line with the chalk. Move the yardstick diagonally across the outline from the upper-right corner to the bottom-left corner and draw a second line. Where the two lines intersect is the outline's center point.

Drill a hole all the way through the cinder block at the center point, using a hammer drill and 12-inch-long 1/4-inch masonry bit. Move to the cinder-block wall's interior side. Center the template over the hole, tape it in place and trace around it with a piece of chalk.

Score the outline on the cinder block's exterior side using a circular saw and a 12-inch diamond blade. Make the score line about 1/4 to 1/2 inch deep. Go around the outline a second time, this time making the cut about 3 inches deep. Score and cut the outline on the cinder block's interior side the same way.

Place a chisel on the cinder block and hit the chisel's handle with a hammer to begin removing chunks. Work from the center out toward the edges. Smooth the edges as much as possible, using the chisel and hammer.

Measure the opening's height and length. Transfer these measurements to a 2-by-12-inch board. Set a miter saw to a 45-degree cut. Cut the boards at the marks so that when put together, they form a rectangle as large as the opening.

Place one of the boards into the opening. Drill a pilot hole through the board and into the cinder block, using a hammer drill. Make sure the pilot hole enters the cinder block and not a hollow portion. Use a masonry bit slightly smaller than the size of masonry screw you will use to secure the board in place. Drive a masonry screw through each pilot hole. Repeat with the three remaining boards.

Measure the opening's length and width along the cinder-block wall, for the exterior framing. Transfer this measurement to 1-inch flat boards. Cut the boards to the appropriate lengths using the miter saw set to 45 degrees.

Place the top board over the opening. Drill pilot holes through the board and into the cinder blocks, then drive masonry screws through each pilot hole. Repeat with the three remaining flat boards.

Center the doggy door over the opening with the hinge bracket resting on the top framing board. Drive 1 1/2-inch wood screws through the hinge bracket's two screw holes to secure the doggy door in place.