A section of damaged or decayed board may require complete replacement. Before you tackle this project, be sure you can find a replacement piece that matches. If you can’t find a perfect match, you may want to “steal” a piece from a less-conspicuous part of the house and then replace that piece with a less-than-exact match.

The object is to cut the damaged piece, remove the nails that hold it in place, pry it out, repair any damage to the building paper, and replace the section. Here’s how to do this:

1) Using a prybar or nail puller, pry out the nails holding the damaged piece. Depending upon the type of siding, it may be helpful to drive a couple of small wooden shingles or wedges beneath the board to pull it outward.

2) Use a square to mark a straight, square line across the board on each side of the damaged area.

3) Set the blade depth on your circular saw so that it will cut almost—but not quite—through the siding. Carefully hold back the blade guard, and make a “plunge cut” just to the waste side of each cutting line. Be careful not to cut into surrounding or lapped boards; if necessary, pry adjacent boards from the wall, and finish your saw cuts with a chisel and hammer.

4) On tongue-and-groove siding (or other interlocking types) make another cut lengthwise across the damaged area so you can easily split the piece in half.

5) Repair any cuts or tears in the building paper beneath the siding by spreading roofing cement over them with a putty knife.

6) Cut a replacement piece to fit exactly. When replacing a piece of tongue-and-groove siding, cut the back side of the groove edge off. Fit the replacement piece into place, and nail it to wall studs with 8d galvanized finishing nails.

7) Set the nail heads and fill the nail holes.

If you’re not used to handling a power circular saw or similar carpentry tools, you may want to hire a handyperson or carpenter, or contact a local siding contractor for the job.