I've installed this Chimney Mount a couple of Decades ago and it still stands. It has been supplemented with a DirecTV installation and 3 HDTV Antennas. Fire Bricks used in Chimneys can be quite strong, yet any Brick may crumble Slightly on the edges under pressure, so glue some small rounded metal angle stock cut about 2 inches long, placed at each corner to facilitate installation. Avoid Strapping over Mortar Joints.