- 1). Hold an open end of a vent pipe against the cinder block wall. Adjust its location so it sits at least 1 1/2 inches away from a mortar joint. Run soapstone around the outside of the pipe to mark the cinder block wall. Set the pipe aside. Ensure the area around the mark is clear of large objects.
- 2). Secure an 8-inch long, 1/4-inch masonry drill bit in a hammer drill. Place the point of the drill bit on the cinder block wall, 1/2 inch above the soapstone line. Drill a hole through the block. Move the drill bit over 1/4 inch from the previous hole and drill another hole. Repeat the process until you have a series of holes around the circumference of the vent opening.
- 3). Align the sides of a cold chisel tip with two drilled holes. Strike the chisel with a 2-pound sledgehammer. Move the chisel over to the next hole in the series. Hit the chisel with the hammer. Continue the process until all holes have a score line between them.
- 4). Hit in the center of the soapstone mark multiple times until the cinder block breaks from the wall. Remove any jagged edges from the hole with the chisel and hammer.
- 5). Move to the other side of the wall. Score between each set of holes as described for the first side of the wall.
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