How to Install a Chimney Cover

Lean an extension ladder against your roof so the third rung from the top is even with the eaves. Position the bottom of the ladder away from the wall at least 1/4 the distance from the ground to the roof for a safe climbing angle. Store gloves and tools in a tool belt to carry them to the roof. Put on heavy work gloves before handling the sheet metal chimney cap. Keep your hips between the ladder rails as you climb.

Measure the chimney flue, or perimeter around dual flues, with a measuring tape to determine the proper size chimney cap. Measure the outside length and width of a single masonry or tile flue that is square or rectangular. Measure the length and width of the chimney top, or outer chimney perimeter around dual flues, and measure the height of the tallest flue. Measure the outside diameter of round masonry or single wall metal pipe chimneys. Measure the inside diameter of all round tile, double wall, triple wall, insulated flues and flexible metal flue liners. Select a cover that fits the measurements and suits your taste.

Slip the base of a chimney cover around the outside of a single masonry flue so that it covers one to three inches of the flue. Tighten the screws around the base with a Phillips screwdriver.

Slip the base of a chimney cap into the inside of a round tile flue and push it down securely. Spread silicone sealer, or the adhesive that comes with such caps, around the perimeter where the flue meets the cap.

Slip the inside base of a chimney cover into the inside of a metal liner or pipe and push it securely into the pipe. Sealers and adhesives are not recommended for metal pipes.

Place a top mounting cap over the perimeter of the chimney top, or over the outer perimeter of the chimney wall. Drill into the concrete or bricks through the holes on the cover with a cordless drill using a masonry drill bit. Secure the cover by tightening masonry screws through the holes with a Phillips screwdriver. Use a Phillips screwdriver bit to install the screws with the drill if necessary.