My outside window sills are getting quite spongy from decay. I asked several people what I should do. Some said to cover the sills with aluminum, some said to replace the sills, and some said fill with a filler material. What should I do?
I’m with the filler people. Dig out decay with hammer and chisel, reaching bare (sound) wood. Treat the space with bleach to kill any decay-causing fungi, rinse, and let dry. Then fill with Minwax’s epoxy wood rot filler. It is a two-part system that is tricky to use but works wonders.
If the decay goes all the way through the sill, chances are you have to replace the entire sill. If the decay is in the front of the sill, you can saw it off and screw on a filler piece of new wood (pressure-treated).
Covering decay with aluminum guarantees more decay.
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I have a piece of three-quarters-inch CDX plywood 6 feet long and 15 inches wide. It is bending along its length. If you put it down arch side down, the distance from the top of the arch to the floor is 2 inches. How can I straighten it out? I want to build a long box with that piece and other pieces. If I put a flat piece of plywood down on the driveway in the sun, how will the piece curve?
The piece bent because the underside (the concave side of the curve) dried out and contracted. The same thing would happen with the flat piece in the sun. The top would dry out, and the curve would be up at each end.
To correct, put the bent piece in the sun, curved side down, put weights on it and see what happens. A better way is to suspend the piece on two 2-by-4s, curved side down, and put weights on the piece until it is slightly bowed the other way. You could wet the underside, which might help.
These are letters from Peter Hotton’s 2003 columns.