Cost to Replace a Rotted Window Sill – 2021

| Last Updated: August 24, 2021

National Average Improvement and Repair Cost







$ 233

$ 50

Would you do this project? According to our survey, 50% of respondents preferred DIY compared to hiring a pro.

Photo credit:

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

How much does it cost to replace a window sill? A sill is a prominent part of a window that juts out at its base so a damaged one is an eyesore. The contractor cost to replace a window sill is $233 vs. doing it yourself for $50 and saving 79 percent.

When an old window sill is rotted or damaged beyond repair, the best alternative is to replace it with a new one. Often the drywall at the base of the window is damaged by moisture from condensation or a hungry dog who used the sill as a chewing toy.

Whatever the cause, installing a new window sill provides protection and adds stylish detail to the window. If there is moisture damage to the wall, make the repair and then replace the sill. And if your window was built without a sill, adding a new one will be a home improvement upgrade.

There are vinyl window sills that are installed with adhesive in two styles. One has a straight cut basic style, and the other wraps around the sides of the wall, giving it a custom look.

At the manufacturer’s Web site,, you can learn about the different styles that match your window frame, how to measure a window for a new sill and what’s involved installing one.

A carpenter, handyman or window replacement installer will charge $233 to replace the old sill with 4-linear foot sill that matches the window trim, assuming no repair work like fixing the window frame or repairing drywall on the window or wall is required. That will cost more.

You can buy the new window sill for $50 and do it yourself, assuming you have some carpentry skills and tools, and save 79 percent. You’ll need a tape measure, carpenter’s square, saber or small circular saw, construction adhesive and weatherproof caulking and a caulk gun. You can check out our guide on caulking windows.

That sums it up. Knowing the average cost to replace a window sill lets you compare DIY costs with what you can expect to pay a handyman or window replacement installer. 

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.