How to patch wood siding

Q: When inspecting the exterior of my home, I noticed some damage to the wood siding on the weather side of the structure. Some of the boards are split, and others appear very weathered and splintered. The damage is pretty localized, as if hail or branches struck that section. Should I replace the damaged siding or is there a patch compound or something available to protect the walls? — Jack S., Schenectady, N.Y.

A: If damage to the siding is not extensive — meaning it’s just a few inches of wood here and there — you might be able to scrape out or cut away the splinters, sand, and fill with wood putty. Or, you can shape a piece of scrap lumber to fit and nail and glue it into place — a patch that will last longer, but not necessarily look good.

However, if the damage is more extensive, or you’re worried about the ability of a patch to keep water from seeping behind the siding, consider replacing the entire section.

Wood siding is installed in a staggered pattern so that the joints don’t line up — which would make them more noticeable, and more importantly, would allow water to seep between the seams. It’s best to follow the pattern when replacing siding, so you’ll need to remove boards individually.

To do so, carefully pry up the board above the one to be removed, and place wood spacers under it to expose the nail heads of the damaged board. From here, you can use the pry bar to “rock” the damaged board and raise the nail heads a bit so they’re easier to remove. Or, if you have a reciprocating saw, pry up the damaged board, put spacers under it and then carefully cut the nails from underneath. Pull the board off (leaving spacers under the top piece of siding so you can slip a new piece in).

Once all the damaged siding is removed, check the wall’s underlayment — the sheathing and building paper that provide a breathable seal between the siding and the interior of the house. Replace damaged materials. If the building paper has small tears or holes, patch these with roofing cement. Then, head to the lumber yard and have new siding cut to match the old.

Single siding boards can be installed by slipping them underneath the undamaged boards above and nailing them into place with siding nails.