Windows are close to the weather, and—that being so—they take a lot of abuse from the elements. More often than not, peeling paint from wooden windowsills and frames can be sourced back to moisture. When snow melts on your sills, when rain stands along them, water eventually seeps into the paint film. Later, it evaporates. But it evaporates under the paint film, which causes loss of adhesion and peeling. Another common culprit is poorly sealed, improperly caulked framing, or else caulking that has itself cracked or peeled, allowing water to compromise the paint.
To repair peeling wooden sills and frames, start by removing as much of the damaged coat as possible, sanding or scraping down to the bare wood. If more power is needed to remove the damaged paint, you can also make use of a chemical stripper or a heat gun—but be careful. When using either of them, make sure to follow all the manufacturer’s instructions, and keep in mind that both methods can damage unprotected glass and sealants.
Once you’re left with the bare wood, use a damp rag to clean any dust or debris off the surface. Then let any residual moisture evaporate. This part is important: let it dry thoroughly. Caulk wherever you notice damage to the old sealant, especially at 90-degree angles and in the nooks and crannies that let in moisture. After that, apply a good primer to the surface and repaint. Especially when working on the exterior of the window, consider using an oil-based gloss paint to protect any surface that’s exposed to snow or rain. Replacing your old windows with storm windows and using dehumidifiers can also help prevent peeling from striking your window sills and frames again.
So to cap things off, remember: windows—being constantly exposed to sun and water—are bound to present challenges to homeowners. But by properly stripping cracked and peeling paint, resealing where necessary, and repainting after careful prep work, you can fix the problem now. If done properly, your work will be much longer-lasting. And that’s that! No more peeling window sills and frames.