Kentucky Home Exteriors

Signs of Window Wood Rot and How To Fix It

window wood rot

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Window wood rot is a real pain and can be an expensive problem. Wood rot might be to blame if you notice discoloration, soft or spongy wood, or visible damage to your window.

If you regularly inspect your windows and catch wood rot in time, you can repair the damage before it worsens. But if the wood rot is extensive, you may need a complete window replacement.

What Is Window Wood Rot?

Window wood rot is the deterioration or decay of wooden windows due to prolonged moisture exposure. Wood rot is mainly caused by fungi that break down the wood fibers.

Rain, leaks, condensation, and improper sealing can cause moisture damage. Sustained moisture damage paves the way for fungal infestations. The spores settle and start to grow on the wet wood. The fungi extend thin threads called hyphae into the wood and, along with an enzyme, break down the wood fibers. As the wood decays, you can see visible signs of damage, like discoloration.

Signs of Window Wood Rot

Signs of wood rot on your windows are easy to spot if you’re performing regular inspections.


Do you have a pesky mug ring on your coffee table? When wood is exposed to moisture, it changes color. In the case of your window frame, you may notice darker patches. Fungi growth can also cause discoloration.

Soft, Spongy Wood

Wood rot weakens the fibers of your wooden window frame. So, if you press on the frame with your finger, it may feel soft and spongy.

Visible Damage

Moisture affects the structural integrity of wood but also damages the finish. You may notice cracked and peeling paint, visible decay, or holes.

Fungal Growth

Mold, mildew, and fungi are red flags of wood rot. You may notice them growing on or around your window frame.

How To Fix Windows Damaged By Wood Rot

Assess the Damage

  • Find the areas of your window frame that need to be repaired. Check the frame, sill, and sash.
  • Inspect the whole window to see if any structural components are affected.

Remove the Damaged Wood

  • Cut away the damaged sections of your window frame until you reach healthy wood.

Apply Hardeners

  • Use a wood hardener to strengthen the wood fibers and prepare the surface for an epoxy wood filler.
  • Next, use epoxy to fill any gaps. Epoxy is resistant to moisture and provides a durable, long-lasting repair.

Sand, Prime, Paint

  • Once the epoxy has cured, sand it with a coarse grit sandpaper before moving to a finer grit.
  • Use an exterior-grade wood primer. It will help the paint stick and provide extra moisture protection.
  • Choose a high-quality paint or stain to add another level of moisture resistance.

Find the Problem

  • Repairing the damage is one thing, but you have to find the source of the problem. Fix leaks, improve drainage, and inspect flashing to prevent further water damage.

If you catch window rot early enough, you can repair it yourself. But if it’s extensive, you may need a full window replacement. If DIY isn’t your thing, contact a professional company for an inspection.

When making as important a decision as replacing your windows, you want to make sure you’ve made the right choice. Consulting with a professional can help make this important decision easier.

Got Window Problems? Let Us Help

At Kentucky Home Exteriors, we offer free consultations. We’ll inspect your window and talk you through your options. You will want to consider the overall condition of your existing windows, which often determines how much work you need.

So, if you think window wood rot has set in, contact us for help.

Chris Demuth

Chris DeMuth

Founder & CEO

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Owner & CEO

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