How to Restore Window Sills Before Painting

Updated February 21, 2017

Do-it-yourself home restoration can save homeowners time and money when it comes to projects like windowsills. Instead of hiring a professional to tackle the job and paying labour costs, restoring windowsills can be done by a determined homeowner with the right tools. You want to restore these sills before you apply a new coat of paint because once you paint over them you won't be able to fix any underlying problems.

Scrape away any loose paint chips with your metal scraper. Dispose of all old paint safely in dustbins or trash bags to avoid pets or children from coming in contact with them.

Remove remaining paint with a heat gun. Direct the heat gun at the paint areas until it blisters, and then scrape away the remaining paint. Continue until most of the paint is removed from the surface; a few chips here and there will not harm your painting project.

Probe the surface of the wood with a small screwdriver, looking for soft spots in the wood. If you hit an area that is so soft to the touch that you can penetrate it with your fingernail, you will need to remove it in order to preserve the strength of your sill.

Remove soft areas of the wood by prying them out with the screwdriver. You can also use a chisel or a wire brush to remove these areas.

Fill in any holes in the wood window sill with epoxy filler. This material is available at hardware and home improvement stores. Apply to the holes and smooth over with a putty knife. Allow the epoxy to dry completely before continuing; consult your product for detailed drying time.

Paint epoxy sealant over the surface of the window sill. Also available at hardware and home improvement stores, epoxy sealant will penetrate the wood to prevent rotting or moulding after the surface is painted. Allow the sealant to dry completely before painting; consult your product for detailed drying time.


Use a metal scraper with a wooden or metal handle. Plastic handles can melt under the heat of the heat gun. You can use fine grit sandpaper to remove paint instead of a heat gun. An electric palm sander will make the job go faster. The wood of the window sill must be completely dry before you apply epoxy filler, or else the epoxy will not dry properly.


You can use paint thinner or paint stripper to remove paint from old window sills, but read all instructions and warnings carefully. These chemicals can damage some surfaces, and can be dangerous if inhaled or swallowed.

Things You'll Need

  • Metal scraper
  • Dustbin or bags
  • Heat gun
  • Small screwdriver
  • Epoxy filler
  • Putty knife
  • Epoxy sealant
  • Paintbrush
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About the Author

Samantha Volz has been involved in journalistic and informative writing for over eight years. She holds a bachelor's degree in English literature from Lycoming College, Williamsport, Pennsylvania, with a minor in European history. In college she was editor-in-chief of the student newspaper and completed a professional internship with the "Williamsport Sun-Gazette," serving as a full-time reporter. She resides in Horsham, Pennsylvania.