Repairing Rot and Decay in Wooden Frames
When Good Wood Goes Bad (and How to Bring It Back)
Wood rot is a four-letter word in the world of restoration—but it doesn’t have to mean disaster. With the right techniques and a little know-how, you can save most wooden window and door frames, even when decay has taken hold.
This week, we’re diving into how to identify rot, assess the damage, and restore integrity and beauty to your historic frames.
What Causes Rot?
Moisture is the usual culprit. Combine it with time, poor maintenance, and organic materials (hello, wood), and you get a playground for:
Fungi – The microorganisms that break down wood fibers
Insects – Termites and carpenter ants love damp wood
UV exposure – Sunlight breaks down protective finishes, speeding up moisture intrusion
Where Rot Usually Happens
Look closely at:
Bottom corners of window and door frames
Sills and lower rails
Jambs where water pools or collects
End grain exposures (cut edges)
Exterior casings and trim pieces
Pro Tip: If the area stays wet for 48+ hours, it’s a rot candidate.
How to Spot the Signs of Rot
🪵 Soft or Spongy Wood – Press with a screwdriver or pick; if it sinks in, it’s compromised.
🪵 Peeling or Bubbling Paint – Often a sign that moisture is trapped underneath.
🪵 Dark Staining or Discoloration – Indicates prolonged exposure to moisture.
🪵 Cracks or Gaps in Joinery – Wood pulls apart as internal structure breaks down.
Step-by-Step: How to Repair Rot in Wooden Frames
1. Remove the Rot
Use a chisel, oscillating multi-tool, or detail saw to cut out decayed wood.
Go back until you reach solid, dry wood.
2. Treat the Area
Apply a wood consolidant to stabilize surrounding fibers.
This soaks in and reinforces what’s left.
3. Patch the Area
Option A: Epoxy Wood Filler
Two-part epoxy can be molded and sanded to match the original profile.
Option B: Wood Dutchman (Splice Repair)
Cut a new piece of wood (ideally same species) to fit the missing section.
Glue and clamp in place for structural strength and a clean finish.
Pro Tip: Use Accoya or Red Grandis for replacement parts—they’re rot-resistant and blend beautifully with old wood.
4. Sand and Blend
Once patched, sand smooth and feather into the surrounding surface.
Match profiles using hand planes, rasps, or sanding blocks.
5. Prime and Paint or Seal
Use oil-based primer or shellac on bare wood and epoxy.
Finish with high-quality, breathable exterior paint or sealant.
Preventing Future Rot
🛡️ Maintain paint and caulk regularly, especially around joints.
🛡️ Keep gutters and downspouts clear—avoid splashback on frames.
🛡️ Ensure proper flashing around windows and doors.
🛡️ Inspect yearly for moisture intrusion.
When to Replace Instead
While most rot can be repaired, sometimes replacement is necessary:
If more than 40–50% of a structural component is compromised
If damage is too deep or widespread for epoxy or patching
If rot affects load-bearing sections of a door or window frame
Even then, opt for custom wood replication to keep the historic look intact.
Conclusion: Rot Happens—But You Can Handle It
Wood rot might look ugly and intimidating, but it’s almost always fixable with the right approach. Whether you patch it with epoxy, splice in new wood, or call in a pro, the key is early intervention and proper materials.
Remember: your historic window or door frame has likely weathered 80 to 100 years already. With a little help, it’s got at least another century in it.
