How to Repair the Rot on an Old Window Caused by Condensation

Dig all of the soft, rotted wood out of the window using a chisel. Wear safety glasses and work gloves.

Drill 1/4-inch-deep holes into the gouged, solid wood in the window using a power drill. Slope the holes at a 45-degree downward angle and space them 1 inch apart.

Put on chemical-resistant rubber gloves and an organic vapor respirator approved by the Occupational Health And Safety Administration.

Mix the two-part epoxy consolidant in an 8-ounce plastic squeeze bottle. Follow the specific mixing proportions provided by the epoxy system manufacturer since different brands of epoxy systems vary.

Squeeze the mixed consolidant into the drill holes in the window, thoroughly saturating them. Work the consolidant into the holes and across the gouged wood using a disposable paintbrush. Let the consolidant cure in the holes for 30 minutes.

Scoop equal portions of the two-part epoxy wood fillers onto a clean mixing board using separate scooping sticks for each wood filler. Mix the wood fillers with a putty knife for a few minutes.

Pack the mixed epoxy wood filler into the grooves in the window using the putty knife. Slightly overfill the gouges with the filler to permit shaping and sanding. The epoxy filler starts to dry in 30 minutes so work efficiently. Once you are done filling the gouges, let the filler cure overnight.

Rub a coarse rasp over the excess wood filler to shape the filler to match the surrounding window surfaces. Remove much of the excess filler, leaving only enough to sand.

Sand the remaining excess filler using 80-grit sandpaper, followed by 120-grit sandpaper. Smooth the patched wood to ensure it’s level with the surrounding window.

Wipe all sandpaper dust off the window using a tack cloth. Put painter’s tape along the sides of the window to prepare for priming and painting.

Strip any loose paint off the entire window using a scraper. Wear the safety glasses when scraping the window.

Brush exterior latex primer onto the entire window using a paintbrush. Use smooth strokes to evenly seal the wood. Let the primer dry overnight.

Coat the dried primer with exterior latex paint. Brush the paint smoothly over the entire window using a clean paintbrush. Let the paint dry overnight.