How to Repair a Masonite Lap Board Siding With a Hidden Nail

It protects the home from moisture, wind and other elements. Because the boards are installed using a blind nailing technique, it can be tricky to repair and replace damaged sections. By working carefully and using the right tools, you can repair lap board siding to restore the appearance of your home.

Replace a Full Board

1. Cut away any caulk or paint around the top and bottom edges of the damaged board using a utility knife. This will make the board easier to remove and replace.

2. Slide a chisel under the bottom of the damaged plank and gently pull it away from the wall. Once the board has been pulled far enough away from the wall, place a pry bar under the board. Line up the pry bar with the back of one of the nails in the board, then tap the pry bar with a hammer to push the nail out through the front of the board. Repeat this process to remove all nails from the bottom of the board.

3. Place wedges or shims under the bottom of the board to hold it away from the wall. Slide a sawzall behind the board and use it to cut through the hidden nails at the top of the board. Once all the nails are removed, pull the board out of place by hand.

4. Place a new piece of hardboard siding into the opening. Tap the bottom of the board with a hammer and tapping block to force it under the row above. Face nail this board along the top and bottom edges to connect it to the adjacent rows.

5. Cover the nail heads with caulk and paint the new board to match the rest of the siding.

Replace a Small Section

1. Mark the location of the studs on either side of the damaged area.

2. Cut the board down the center lengthwise from stud to stud. Do not cut or damage the studs you marked in Step 1. Once you've made the cut, remove the lower half of the board by hand.

3. Chisel out the upper portion of the board using a hammer and chisel. You can leave the hidden nails in place, but remove as much of the excess wood as possible.

4. Cut a new piece of hardboard siding to the same length as the one you removed. Slide it into the opening so that it is overlapped by the row above. If the hidden nails make it difficult to line up the boards, cut the board across its length until it lines up with the rest of the row.

5. Face nail the board along the top and bottom edges to secure it in place. Sand the joints on either side of the patched area, then paint the board as needed to match the rest of the siding.