How to Cover Fireplace Vents

Measure the length and width of your vent hole and add 1 to 2 inches to each side of the measurement. Write this modified measurement on a piece of paper.

Purchase two or more sheets of metal tin. Using a carpenters square, scratch out the rectangular area of the same measurements you wrote down in Step 1. Cut the rectangular cover out of the tin sheet with a pair of tin snips.

Apply a heavy bead of caulk around the edge of the vent you desire to cover. If you only desire a temporary seasonal cover, use foam window sealing strips instead. Place the tin over the top of the your chosen seal and hold it in position.

Drill holes 1/4-inch from the edges of the tin. Drill one hole in each corner and one hole between the corner holes on each side, drilling all holes with a properly sized bit that matches the size of masonry screws you will use to mount the panel. While drilling, squeeze lightweight machine oil onto the bit to prevent overheating and damage to the bit.

Screw the panel down tightly over top of the underlying seal with your masonry screws, creating a tight seal to prevent moisture and air leakage.