How to Replace Fiber Cement Lap Siding Boards

Occasionally, damage will occur to your home requiring you to replace a section of your fiber cement lap siding. This multi-step process can be done successfully by do-it-yourself homeowners, and can improve the look of your home and protect your investment.

Step 1. Preparation

Determine the amount of the siding that needs to be replaced. Order or buy any replacement pieces. Remember that many fiber cement boards are smooth on one side and faux wood grain on the other. Some brands are able to be used on both sides while others sell 2 different products – make sure you get the right one for your job.

Step 2. Removing Damaged Lap Siding

Using a pry bar, gently lift the bottom edge of the overlapping siding. Work your way down the board prying the bottom edge up and loosening the nails. This will allow you to remove the nails without damaging the top piece of siding. Occasionally there are stubborn nails, which require cutting with the reciprocating saw or hacksaw. Remove the nails, and countersink any nubs that might prevent your new board from sliding up under the old. Use wood shims to hold the top board away from the wall while you continue to remove nails along the length of the board. Hint: If you are removing more than 1 level of siding in an area, start at the bottom and work your way up. When you reach the top board you're trying to remove, perform the step above. A reciprocating saw can be used to make a vertical, cut so you can remove a partial piece of siding.

Step 3. Replacing Fiber Cement Siding

Check the area behind your repair for any damage. Replace any damaged vapor barriers or rotting wood. Siding is always hung starting at the bottom, which is where most repairs are needed. If your repair includes the very bottom tier of siding, add a spacer strip the thickness of your siding along the entire bottom edge, to mimic the angle of your overlap. Fiber cement lap siding is heavier than wood, and requires a special diamond tipped blade or a tungsten-carbide saw blade to cut. Use a chalk line to create a reference mark for the first or bottom piece of siding. A long piece of siding will sag in the middle, so use temporary blocks to hold it in place while you attach. Once you have replaced all the boards, working your way from the bottom up. Use the nail holes on the top board to attach your very last piece. Only caulk button joints-never horizontally along lap siding.

The finishing touches on concrete siding

Wear protective eye gear and a facial mask, because cutting cement board siding kicks up a lot of dust. It's always a good idea to pilot nail or screw holes, although it will dull a drill bit very fast. Prime and paint for long-lasting and professional finish.