Dear Angie: When putting siding on a side-board house, should you remove the rotted boards first, even if they're just rotten on the ends? Would there be any problems with the new siding if I didn't remove the rotted boards? — Peg P., Knightdale, N.C.
Answer: If you're installing fiber cement siding, you should remove all existing siding, the professionals tell me. If you're installing vinyl siding in place of existing hardboard siding, which I'm guessing is the more likely scenario, I recommend you replace any rotten wood before putting on the new siding.
Vinyl siding might be able to be installed over boards that are slightly weathered, but not if they're rotted or the wood is soft, because you could end up with a few potentially major problems.
First, the nails used to hang the new siding need to be anchored into a solid surface. If the wood is soft or rotted, the nails will not be secured into that surface. The result? Your new siding could fall off.
Second, moisture in the rotted wood behind the new siding is an invitation for trouble, including bugs, mold and mildew. Because they're concealed, those small issues could get very big — and very expensive — very quickly.
A qualified siding professional should be able to evaluate your existing surface and make the right recommendation. Be sure your siding pro thoroughly inspects the surface with you during the estimating process. You can share your concerns about the existing wood to give him or her a better understanding of the issue, and he or she also can also determine other potential problems before starting the project.