In this video, This Old House general contractor Tom Silva saves a rotting window with a two-part epoxy filler.
Steps for fixing rotted wood with epoxy
- Use trim router or rotary cut-out tool fitted with a V-shaped bit to grind out all the rotted wood. Stop when you reach sound, solid wood.
- Use a paint scraper to scrape off any old paint.
- Mask off the area around the repair with painter's tape.
- Take a narrow paintbrush and apply an epoxy bonding agent to all of the exposed wood.
- Hold a 4-inch-wide plastic putty knife against the bottom end of the casing, and trace the casing's profile onto the blade of the putty knife.
- Cut the casing's profile from the knife using aviation snips.
- Squeeze some epoxy onto a Lexan panel and thoroughly mix it with a putty knife.
- Force the epoxy into the cavities where the rotted wood was removed.
- Smooth the epoxy with a putty knife.
- Hold a straightedge against the underside of the windowsill, then strike off the epoxy with a putty knife to fill any remaining voids and create a perfectly straight line.
- Use the putty knife that was trimmed with the aviation snips to shape the epoxy to match the original casing.
- Allow the epoxy to cure overnight, then sand it smooth and apply one coat of primer and two topcoats of paint.