What you need:
- a straight piece of board 1 inch thick by whatever width you want (for the front overhang) and length of your window plus any addition on each end.
- wood glue
- finish nails
- an air compressor with nail gun — not necessary, but really nice to have; a regular hammer and a careful but strong and straight aim will work just fine
- semi gloss paint, I used two coats then applied a third to the top only after the sill was attached
I used a 1×6 which gave me about a 3 inch extension from my existing window. The length extends about 2 inches on either side. I wasn’t sure if the molding underneath should match the length of the window or the wood, so I decided to keep it the length of the original window frame. I found a semi gloss paint that I had in the garage cabinet (most of our paint comes from Home Depot), which was perfect because it is easy to wipe clean and we get dust from the empty field behind us. We did purchase the board and molding at Lowe’s because I think they have a good selection. We are lucky enough to have an nail gun that works with our compressor which makes easy work of the nails putting it together. Finish nails work great for this project. You may want to use a bit of wood glue also when attaching the molding and the small side pieces to make sure your new sill is nice and strong! I painted the sill, as you can see in the pictures, before my husband nailed it on the original sill.
I remember houses used to be built with beautiful wood windowsills. There is something about that smooth enameled surface that appeals to me! Look at the difference a piece of wood and molding made! So easy to wipe clean. I’d love to see pictures of your new ‘old fashioned’ sills!