How To Repair Rotted Wood In An Exterior Window Frame

An old window frame with peeling paint and rotting wood.
  • 2-3 hours
  • Intermediate
  • 50-200
What You'll Need
Chisel or flathead screwdriver
1/4-inch drill bit
Epoxy wood consolidant
Epoxy wood filler
Putty knife
Painter's tape
Eye protection
Respirator or dust mask

Rot is a persistent enemy of homeowners who make use of wooden window frames on their exterior. Outside, the wood is exposed to the elements, especially moisture, and in many cases, there will come a time when rot sets in and destroys some of the beauty of the home. Before it spreads to the entire window frame, however, you should follow these steps to repair it.

Step 1 - Inspect the Extent of the Damage

Before deciding to repair the window frame, make sure that it can be repaired first. Check that the rot has not infected a huge area of the frame, because if more than ten percent of the wood is damaged, then the best option is to replace it entirely. However, small rotten areas can be repaired using epoxy products.

Step 2 - Remove the Rotted Materials

To remove the rotted parts of the window frame, take a chisel or a flathead screwdriver and gouge it until the healthy parts are revealed. Use a brush to scrub the surfaces afterward and clean away the debris.

Step 3 - Drilling Holes

Use a 1/4-inch bit to drill holes into the healthy wood you have left; space them out about an inch apart each. These will ensure that the fillers have a secure hold onto the wood. Then, make sure to clean the frame to get rid of any dust and debris before proceeding with the next steps.

Step 4 - Apply Epoxy Wood Consolidant

Prep the consolidant according to manufacturer’s instructions, and then apply it to the affected area, making sure to fill in the holes you drilled. Allow the wood to absorb the epoxy and apply a second coat when it dries. A thin layer of consolidant will ensure that the wood is well-strengthened before the application of the epoxy filler.

Step 5 - Apply the Filler

The filler will make the repair complete because it will allow the window frame to be restored to its original dimensions. To apply it, prep the product according to the manufacturer’s instructions. Place a good amount of it onto the damaged area and mold it to conform to the shape of the frame. Use a putty knife to press the filler firmly into place, and allow the product to dry for about 24 hours (or the recommended waiting time).

Step 6 - Prep the Window Frame for Painting

Use rough-grit sandpaper to level the hardened epoxy with the window frame. Go over the surface with fine-grit sandpaper afterward to create a smoother surface. Wipe away dust and debris with a rag once more to make sure nothing interferes with your paint job.

Step 7 - Paint

Make sure when repainting your window frame that you choose a material reserved for outdoor use. Preventing future rot starts here; interior paint simply can't stand up to wear and tear caused by weather, moisture, and sun exposure, and it will begin to peel and crack, leaving the underlying wood vulnerable. A good exterior paint will make sure the healthy wood and the filler you've added stays protected.

Choose a color that matches the other exterior window frames, or buy enough paint that you can repaint all of your windows for a consistent look. Lay strips of painter's tape alongside the frame to protect the glass, and then begin painting.