How to Repair Rotted Windows

Dig all of the soft, rotted wood out of the wooden window, using a cold chisel. Continue scraping out rotted wood until you reach solid wood.

Drill several holes into the solid wood, using a 1/4-inch drill bit. Space the drilled holes approximately 1 inch apart and drill them as deep into the wood as possible without going completely through the wood.

Brush liquid epoxy consolidant liberally over the solid wood, using a disposable paintbrush. Allow the liquid epoxy to permeate the drilled holes and surrounding wood for five minutes.

Continue applying the liquid consolidant until the solid wood quits absorbing it. Let the liquid epoxy product cure 24 hours.

Prepare a two-part epoxy filler formula to fill the depression in the wooden window. Using a putty knife, thoroughly mix equal parts of the epoxy resin and curing agent in a bucket.

Work the epoxy filler into the wooden cavity, using the putty knife. Sculpt the epoxy filler so that it follows the window's contours. Let the epoxy filler cure overnight.

Rub fine-grit sandpaper across the cured epoxy putty to smooth its texture. Wipe all sandpaper dust off the window when finished sanding.

Brush a coat of oil-based exterior primer evenly over the repair for sealing purposes. Apply the primer with a non-disposable paintbrush. Let the oil-based primer thoroughly air-dry according to the manufacturer's recommended drying time.

Apply two even coats of latex exterior paint over the primer, using a clean, non-disposable paintbrush (the same brush as previously). Let each coat of latex paint fully dry according to the manufacturer's recommended drying time.