How to Replace a Window Sill

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Whether your window sill is old or rotting away, it might be time to replace it so your house does not begin to look rundown. With a few simple steps, you can have a new, nice-looking window sill.

Removing the Old Window Sill

When removing your old window sill, you want to be careful not to damage the trim or the window sill. You’ll be using the old window sill as a template for the new one, and you’ll be reusing the trim when you’re finished with the whole project. Use a pry bar or a chisel and hammer to pull off any trim that is holding the window sill in place. Remove the nails holding the old window sill in place and remove it carefully.

Making the New Window Sill

You can take the old window sill to the hardware or lumber store with you to find the right size piece of wood for your new window sill, or you can use the existing scrap wood that you have. If you want the window sill to match the existing trim you’ll have to purchase the same type of wood or prime and paint the wood. Measure the old window sill to get the measurements for the new one. Use a saber saw to cut the new piece of wood to size. You can use sandpaper if necessary to smooth off the edges of the window sill.

Installing the New Window Sill

Using your nails, install the new window sill where the old one used to be. Do not hammer the nails all the way in until everything is properly placed. Make sure the window sill is level and placed so the trim can be put back. While the nails are still only partially in, begin reattaching the trim. Once everything is in the correct place, hammer the nails in completely.

Finishing the Window Sill

Once the nails are flush with the wood, use a nail set and hammer to drive the nails below the surface of the wood. Fill the spaces where the nails have been driven down with wood putty. If you are planning on priming and painting the window sill, you can do so before or after you install it. You can also sand and repaint the trim while it is off of the window.

A new window sill can keep a room in your house from looking like it is in disrepair. If you paint the window sill and trim it a different color you can give your room a completely new look. If you want your windowsill to last longer, use hardwood rather than softwood.