How do I replace only part of a window sill?

Sarah Myers
by Sarah Myers

Rain and sun have destroyed the bottom of a west facing indoor window sill. It is a veneer. I only want to replace the damaged bottom not the sides... - see attached photos

Close up view of sill bottom

Right corner

  4 answers
  • Lifestyles Homes Lifestyles Homes on Aug 21, 2019

    Let’s stop where the water damage is coming from first:

    Is this condensation from improperly insulated or improperly flashed windows?

    As long as the condensation, or the leaking water from the window are still coming in, you don’t want to spend the time & the money to fix real wood veneer.

    I would suggest a storm window, as a cheap solution for the winter.


    Then for the wood, you can buy new pieces of veneer that are very small at Michael’s craft stores. I’ve not found any other place, that will sell such small pieces.

    I would take it very sharp wood chisel and cut out the bottom piece. I would simply sand down the side pieces.


    I would put color matched wood putty on the side pieces. And apply two coats of UV stable polyurethane, more like a marine varnish.


    After I have repaired any wood rot underneath the veneer, I would put in the new piece of the new year, that was pre-stained, to match.

    I would use a construction adhesive and a lot of bricks on top of it, to make sure that it completely bonds 100% flat.


    If you want to put two coats of polyurethane on it before you install it, that will be fine.


    I would put more coats, up to two more, on all the surfaces, once they are installed. They will need to thoroughly dry in between coats. At least 24 hours depending on the temperature of the house.

    • Sarah Myers Sarah Myers on Aug 21, 2019

      Cheryl, great info and thank you. The damage is the result of the window left open to often during rain.

  • Kelli L. Milligan Kelli L. Milligan on Aug 21, 2019

    Have you tried just sanding it down flat and restaining?

  • Jewellmartin Jewellmartin on Aug 21, 2019

    After any condensation issues have been resolved and rotten boards replaced and sealed, you could use real Contact Paper to line the whole window frame. Pretend Contact adhesive paper could be thinner or flimsier. But vinyl or ceramic tiles, properly pasted and grouted and sealed, would work, too. Jewell

  • William William on Aug 22, 2019

    to remove and replace the sill....remove the molding attached to it. Cut the sill in two spots close to the center a few inches apart. Now you can pry the sill away from the sides. Use the cut pieces as a template for the new siil. Slide the new sill in place and nail down with finish nails. Replace the molding. Stain and seal with three coats of a water based polyurethane.