Rotting sill still isn’t a simple fix

Q: I try to maintain my home as well as I can by myself. However, there are some things that even the most determined body cannot do. The sills on my outside back windows, which face south, are rotting away. I hope that something can be done simply, but whenever someone gives me advice, they seem to think all the windows and frames need to be replaced. Any advice would be appreciated and considered. I’m a senior citizen on a limited budget. — Bonnie M., via e-mail

A: Normally, when a wooden window frame begins to show significant rotting, it’s best to replace the entire frame — you get a well-fitted, better-insulated window that will last for decades. But it isn’t cheap, and the project is beyond many do-it-yourselfers.

It’s a tough call, without being able to look at your exterior sills, as to whether you can make temporary repairs to them and hold off on replacing the entire window unit. Take a close look at them: Is the rotting only affecting a portion of the exterior wood? Does the rot go through to the interior side? Does the wood crumble away with light pressure?

A rotting window frame can result in a lot of other costs — water damage from moisture seeping through the compromised wood, and high energy bills from poor insulation.If the rot is limited, you can buy a little time — a year or two, max — by filling the cracked surfaces with a two-part wood filler. This product is mixed together and then applied to the damaged area with a putty knife. After it dries, it can be lightly sanded and painted.

Once that’s done, though, start pricing out replacements. The temporary seal will give you a little extra time for this. With parts and labor, you may only be able to replace one frame at a time, but the replacement will be well worth it in the long run.

Home Tip: To check how well a window seals, slip a dollar bill under the sash, close it tight, and try to slide the bill out. If the bill comes out easily, weatherstrip the window.