How to Replace Rotten Tongue-and-Groove Siding

Don heavy work gloves and place a sharp utility knife blade at the left side of the rotted siding board approximately half way from the bottom. Pull the blade across the board using firm pressure to score it. Repeat the process two more times to deepen the score line, but do not cut through the board.

Set the utility knife aside and insert a pry bar up under the bottom edge of the siding, stopping before you reach the score line. Pull the bottom handle of the pry bar toward you to break off the bottom of the siding.

Examine the wall for remaining nails along the exposed portion and remove them using the notched end of the pry bar.

Insert the pry bar at the bottom edge of the undamaged shingle above the exposed side. Tap it with a hammer until it slides under the shingle. Pry the shingle up by one-quarter inch all the way across, but do not detach it.

Insert a hacksaw blade up under the undamaged shingle and saw through the nail heads that hold it in place. Remove the damaged top half.

Measure the exposed area to determine the length of the replacement tongue and grove board. Mark a new board to the proper length and cut it using a circular saw.

Install acrylic latex caulk into a caulk gun and apply a half-inch bead along both side ends of the wall where the replacement siding piece will go.

Insert the piece of siding, tongue side up, under the top siding by 1 inch. Press the bottom groove into the track at the top of the next lowest siding piece using firm pressure.

Insert 1-inch finishing nails 3/4 inch from the left and right bottom edge of the siding using a hammer for extra durability. Apply caulk to the nail heads to prevent water damage.