Repairing Wood Rot | Wood Putty Repair Tips for Rotted Window Sills

July 16, 2017

For the DIY homeowner, repairing wood rot on your window sills may be a good weekend project. But let’s be honest, the photo above depicts an older, damaged window that is well beyond repair. If your windows look like this you better give the Window Repair Guy a call. It’s time for replacement windows if you have this severe wood damage.

Rotted window sills are a common problem in older homes. This is particularly true if the homeowner has neglected their windows and have ignored the routine maintenance required to preserve wood windows. If the damage is minimal, repairs are in order and you should follow our tips below on repairing wood rot.

Simple Steps for Repairing Wood Rot

Inspection: Before you make the decision to repair your existing windows you need to conduct a thorough inspection to determine if repair is a viable option. Take a close look at the entire wood frame, paying close attention to the window sill, to evaluate the extent of the damage. As a rule of thumb, if more than 10 percent of the wood is damaged, it’s time to call in the pros for a window replacement estimate. If the wood rot encompasses less than 10 percent of the window sill or frame, read on.

Remove the Rotted Wood: Remove all of the rotted wood using a wood chisel or large flat head screw driver. Keep scraping until you reach healthy wood. Use a wire brush to scrape away any remaining debris.

Drill Anchor Holes: Drill several 5/16” diameter anchor holes in the exposed healthy wood. The holes should be about 3/8” deep on 1” centers. The purpose of the holes is to provide a solid anchor for the wood filler. Brush or blow off any loose debris.

Apply Wood Penetrant: Apply a coat of Wood Penetrant, a.k.a. Wood Consolidant to the repair area. The penetrant will strengthen and protect the wood.

Apply the Epoxy Wood Filler: Mix the Epoxy Wood Filler according to the manufacturer’s instructions. Use a putty knife to apply the Epoxy Wood Filler to the repair area. Use the putty knife to shape the filler to the original dimensions of the wood. Be sure to push the Epoxy deep into the 5/16” holes. Allow the Epoxy to fully cure before sanding. Depending on the manufacturer, this is generally about 24 hours.

Sand the Filler: Prior to painting, you should sand the hardened filler. Start with a 60 grit sandpaper to remove any high spots, then smooth the surface with a 120 grit paper.

Painting: Clean the entire window frame prior to painting. Apply a generous coat of a high-quality, exterior paint to the repaired window.

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Need a window inspection or assistance repairing wood rot on your windows? Contact our support team at (815)-634-8922.