Fixing Rotten Wood Around a Window Frame

fix rotten wood around a window



What Is Rotten Wood?

Fixing rotten wood around windows, mainly caused by a type of fungus that eliminates wood, and if the wood is left untreated or severely exposed to the weather, it can begin to decay. However, you can fix wood rot on windows yourself, providing you’ve got the right tools and know-how.


Tools You Will Need:

  • Chisel or a wide screwdriver
  • Drill with a ¼ (6mm) inch bit
  • Wet rot wood hardener and wood filler (Ronseal do both)
  • A plastic or metal knife
  • Brush
  • Paintbrush, wood paint & painter’s tape
  • Various grades of sandpaper


One Method For Fixing Rotten Wood Around Windows:


Determine the amount of rot.

Your first step is to identify the amount of wood decay and the extent of it. If there is an excessive amount of wood decay (over 10% of the frame), it’s best to forget about repairs and replace the whole window. And this is because excessive amounts of rot will cause instability in the window frame, which poses a security risk.

Remove the Rotted Areas.

Using your chisel or screwdriver, begin dislodging the rotted wood from the framing until you find the excellent wood underneath. Once you’ve finished dislodging the rot, use the brush to wipe away any leftover debris.

Drill some holes

Drill some holes into the wood using a ¼-inch bit, spacing the holes about an inch apart. Doing this ensures that the wood filler will have a firm hold of the wood. Next, clean away any newly created dust and debris.

Apply the Wood Hardener and Filler


repair care 4 wood filler
Our go-to wood repair system

Apply your wood hardener to the affected area and ensure to fill the holes you drilled. Leave to dry before applying a second coat. It will reinforce the wood before using the filler.

Next, apply a generous amount of filler and mould it to the shape of the frame. Firmly press the wood filler into place using a plastic or metal knife and leave it to dry for the amount of time recommended by the manufacturer’s instructions. Make sure the wood filler is dry before progressing to the next step.

Sand the Area Down

If the filler is dry, take the various sandpaper grades and begin sanding down the repaired area, so it’s level with the rest of the frame. Start with coarse grade sandpaper and progress to a smoother one for a better finish.

Paint the Wood

Firstly, the wood paint that you use should be suitable for exterior use. For a consistent finish, make sure to use a colour that matches your current window frames too. Before you start painting, place strips of painter’s tape along the edge to protect the glass before painting the frames.

Although repairing wood rot via this Method, the wood rot will likely have weakened the frame, potentially compromising the window's security. So while rot repair may provide a temporary solution, we recommend replacing the windows to ensure your home's security will be unaffected.

If you are thinking about new windows & wondering which wood type would last longer, it’s worth considering Accoya Wood. This type of sustainable wood has an estimated lifespan of 80 years & can have any finish applied to it to suit any home.


earthborn clay paint
Farrow and Ball Paint
Manor coatings logo
armstead trade paint logo
Dulux trade paints logo