How to make a new window stool
Photo 1: Mark and cut the window stool to length
Mark a 3/4 x 3-1/2 in. board to length. The stool should project 3/4 to 1 in. (you can decide which looks best) beyond each side casing. Cut to length.
Photo 2: Round over the exposed edges
Rout the top and bottom front edges and the side edges with a 1/4-in. round-over bit once you’ve cut the stool to length.
Photo 3: Mark the cutout
Mark the stool extension by setting your compass 1/8 in. less than the distance from the edge of the board to your window sash. Cut this area away with a handsaw or jigsaw and test the fit. If you have newer windows like those mentioned in the text, skip this step.
Photo 4: Cut and install the apron, then install the stool
Cut a 3/4 x 3-1/2 in. apron that extends to the casing marks, and nail it (use 8d finish nails) to the framing behind the drywall and the windowsill. Then place the stool over the apron and sill, and nail it into both with 6d finish nails.
Classic window trim includes a piece of trim that sits on top of the sill. Called the window stool, it’s the place our grandparents used to set the pie to cool. We’ll show you how to add this traditional feature to your windows, but you’re on your own for the pie!
Our photos show how to make a simple stool for older-style, double-hung windows. The stool board is just a 1×4 (3/4 in. x 3-1/2 in.) that you cut to fit and then round the edges with a router. Because the lower sash of these older-style windows is set back on the sill, the ends of the stool board must be notched to fit as shown in Photo 4.
If you have newer windows, including casement (crank-out) windows, the job is easier. They have a factory-made extension piece that makes them fit flush with the drywall, so you only need a straight piece of wood for the stool. It’s not necessary to notch the ends.
Keep in mind that the stool shown in Fig. A is for larger-scale casing that’s 3/4 in. thick and 4 in. wide. For modern, slimmer casing that’s about 7/16 in. thick and 2-1/4 in. wide, the stool should project from the wall only about 2-1/2 in.
Cutaway diagram of a typical double-hung window with window stool
Use this cutaway diagram to visualize how you’ll install the window spool. Notice that the window stool extends underneath the casing and jamb pieces; you’ll have to remove them before marking, cutting and installing the new window stool.
Required Tools for this Project
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
- Air compressor
- Air hose
- Brad nail gun
- Circular saw
- Coping saw
- Extension cord
- Hearing protection
- Orbital sander
- Pry bar
- Safety glasses
- Speed square
- Stud finder
- Tape measure
- Wood chisel
Required Materials for this Project
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.
- 3/4 x 3-1/2-in. board
- 6d finish nails
- Finish nails