Cost to Repair a Rotten Window Sill – 2021

| Last Updated: August 24, 2021

National Average Improvement and Repair Cost







$ 240

$ 65

Would you do this project? According to our survey, 54% of respondents preferred DIY compared to hiring a pro.

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The average price to Repair a Rotten Window Sill noted above is cost data to compare a contractor’s estimate with doing it yourself.

How much does it cost to repair a window sill? The contractor cost to repair a rotten window sill is $240 vs. doing it yourself for $65 and saving 73 percent.

A window sill on the exterior of a house is not easy to replace because it’s an integral part of the window frame and is difficult to remove. Yet even if you’re not a master carpenter, you can repair a damaged sill by rebuilding, shaping, and sanding it to conform to its original appearance

The location of the window sill can be an issue. If it’s on the second floor and you have to hike up a ladder or if the repair work is difficult to reach, the job may be more than the basic repair.

The material to use is a two-part wood filler and hardener from Minwax, or a wood filler and stabilizer from Bondo. Both are available at hardware stores and home centers. The filler is designed to fill holes and gouges in the wood, and the hardener or stabilizer is formulated to strengthen and reinforce the decayed or rotting wood.

When the repair area is dry, you sand and smooth the surface so it can be finished with a primer and paint to match the existing finish.

A handyman will charge $240 to rebuild a window sill with these materials, which includes labor and material. But you can buy them for $65 and do it yourself, saving 73 percent.

Before you begin the repair, remove any loose paint with a wood scraper, then use a putty knife to apply the filler or a disposable bristle brush for the hardener. To smooth the surface, use a pad sander and sandpaper before finishing the surface with a primer and paint.

The bottom line: compare the price of a contractor’s bid torepair a rotten window sill with what it costs to do it yourself and make your decision.

Dealing with some more window problems? These might help:

Welcome! We hope you’ll find the job costs of home improvement projects useful when you’re deciding whether to do a job yourself vs. hire a contractor. We’re the authors of 20 home improvement books, most notably Home Improvement for Dummies©, Bathroom Remodeling for Dummies©, Carpentry for Dummies©, Plumbing for Dummies©, and Painting and Wallpapering for Dummies©. Our most recent book Fix It and Flip It is in its second edition. We’ve appeared as home improvement experts on television programs such as CNN, Dateline, the Today Show, HGTV and many others.