How to Build a Window Seat
If you have a bay window, you’ve probably thought about building a window seat. Perfect for reading, relaxing, and adding some storage, a window seat is something you can do on your own in a day or two. All you need are some basic carpentry skills, tools, and supplies. Here’s what you’ll need for this satisfying DIY project:
- Measuring tape
- Stud Finder
- Pry Bar
- Chalk Line
- Quick Square
- Circular Saw
- Table Saw
- Power Drill
- Drill Bits
- Miter Saw
- Utility Knife
- Staple Gun
- Paint Brushes/Roller
- Hammer & Nail Set or Pneumatic Nailer with Compressor
- ¾-in. Thick MDF Panel
- ½-in. Thick MDF Panel
- ¾-in. X 3 ½-in. MDF
- 5/16-in. X 11/16-in. Molding
- 3-in. Screws
- 2-in. Screws
- Piano Hinge
- Spring Lid Supports
- Construction Adhesive
- Yellow Wood Glue
- 3D Finish Nails
- 1-in. Brads
- Foam Cushion
When taking on this DIY task, be sure to equip yourself with the proper safety gear. Throughout the video, we’ll alert you regarding when you should and should not use the safety gear.
Mark ledger height on wall. You’ll begin by marking your new seating’s ledger height on the wall. Average seating is about 18 inches high. If you plan on putting a cushion on top of your window seat, subtract the cushion thickness plus ¾ of an inch, the thickness of the seating panel, from 18 inches to get the ledger height. Mark this measurement at the center of the back wall. Then use a level to mark a line at that height on all three walls.
Find studs. Locate wall studs along your lines with an electronic stud finder. Mark each location slightly above the ledger line, so they’re visible once the 2×4 is in place.
Install back ledger. Measure the length of the back wall. In this particular project, the ledger was cut to fit around a wall outlet, with ends cut at 22 ½ degree angle to fit into corners. If your project calls for similar cuts, measure your corner angles with a protractor and angle finder. Then use a miter saw to cut your 2×4 to length. Place the top of the 2×4 along your ledger line and secure it with two three-inch galvanized or ceramic coated screws to each stud.
Remove baseboard. Your baseboard will need to be removed or cut back from the front of each side wall, so the window seat us flush against the wall. Remove baseboard with a hammer and pry bar. To remove nails, tap them with a hammer and pull them out with pliers. For this window seat, we removed all of the baseboard, but feel free to leave the baseboard along the back wall if you’d like.
Cut front frame plates. Measure the area where you’ll be installing the front frame plates. Determine the angle of the wall with a protractor and angle finder and cut the ends of each plate with a miter saw.
Lay out stud locations. Stack the plates together and lay out stud positions, centered 24 inches apart, along the plates. Mark an X to indicate the stud side of the line. Then use a quick square to strike a cut line for each mark. You’ll need two more studs for the ends.
Cut studs. To determine the length of the studs, stack the plates and measure from the top of the plates to the line on your wall. Mark your 2×4 with a quick square. Then use a miter saw to make your cuts.
Assemble front frame. Place each stud on its line and attach with two three-inch screws.
Install front frame. Put the front frame in place and secure it to the floor with three-inch screws. Start with a screw on each end. Add screws between studs and at the top of the frame.
Cut sidewall ledgers. To determine the length of the sidewall ledgers, measure from the inside corner where the back ledger ends to the back of the front frame. Cut the sidewall ledgers with a miter saw, using the same angle as the back wall ledger in step three.
Install sidewall ledgers. Place each sidewall ledger along your horizontal lines. Pre-drill, then secure with two three-inch screws in each stud.
Measure for crosspieces. Two crosspieces will run wide side up between the front frame and back wall ledger to support the seat board and lid. They’ll be located at the ends of the back wall, where the side walls begin. Measure to find their length, mark with a quick square, and make your cuts with a miter saw.
Install crosspieces. Set the crosspieces in place. We recommend pre-drilling holes for the screws attaching the crosspieces to the front frame and back wall ledger. Use two screws for each end. Check for level as you work and adjust if needed.
Cut front panel. Determine the front panel height by measuring from the bottom of the seat to the top of the frame. Cut a piece of half inch medium density fiber board, commonly known as MDF to this width with a circular saw. Use a chalk line to snap a cut line. Then make your cut, using a guide as needed.
Install front panel. Dab construction adhesive on the front frame and put the front panel in place. Pre-drill four nail holes with a 1/16-inch diameter bit and attach the panel with 3D finish nails. Sink the nails in place with a nail set.
Measure for top and bottom molding. The molding arrangement for this project’s window seat matches a built-in headboard in this bedroom. It consists of frames made from ¾ inch x 3 ½ inch MDF boards, with small panel molding around the inside of each panel. If you’d like to replicate this in your own project, start by measuring for two pieces of three-quarter inch MDF to fit across the top and bottom of the front panel. If your wall is flat, simply use the length of the front panel. Cut the MDF to width with a table saw. Then cut to length as needed. This panel was over eight feet. So we used two pieces for the top and bottom.
Cut and install top and bottom molding boards. Use a miter saw to cut the top and bottom molding to match the angle of the sidewalls. Apply wood glue to the back of the board and set it in place. Pre-drill four nail holes and use 3D nails to attach the molding to the front panel. Use a nail set to sink the nails and a level to ensure your installation is properly aligned as you work. Install both the bottom and top panel this way.
Make and install vertical boards. When it comes to fitting moldings, scribing in place is always easier than measuring. Start by cutting all vertical boards about half an inch longer than the distance between top and bottom boards. Place one end of a vertical board against the bottom board. Then use a utility knife to make a notch where it meets the top board. On a flat surface, put the knife back in the notch. Slide a quick square up to the knife and score across the board. Then use a miter saw to make your cut. Install the boards with glue and nails as you did with the top and bottom boards.
Install inner molding. Measure, then cut both ends of a piece of panel molding at a 45 degree angle. Apply glue to the inside edge. Then set the molding in place. An 18 gauge nailer can speed along your installation. If you don’t have access to this tool, pre-drill each hole and hammer in one-inch brad nails, sinking each nail as you work. Work your way around the inside of each panel, installing all inner molding the same way. Be sure to wipe away any excess glue as you work.
Finishing the front panel. Now, you’ll begin some of the finishing touches for your window seat. Start by filling nail holes with putty. Then caulk along the inside and outside edges of the inner panel molding, wiping away excess as you work. Once the caulk and putty have dried, sand until smooth.
Top panel cuts. Create a cut list and make a diagram of the pieces you need for the top of the window seat. There will be four parts total, three decking pieces and a lid. Make sure the side pieces are centered in the support piece. A protractor and angle finder will help you lay out the angle of the sidewalls. Use the diagram to mark your cuts on the MDF. Once you’ve made all your marks, make your cuts with a circular saw or table saw if you have one large enough. When you’re done, test fit the pieces to ensure a good fit.
Install top pieces. Apply construction adhesive to the frame of the window seat. Then set it in place. Pre-drill nail holes. Then secure with 3D finish nails, sinking the nail holes with a nail punch. Do this for both sides and the back edge piece.
Install lid. Install the piano hinge to the back edge of the window seat lid. Pre-drill and attach with provided screws. Set the lid in place. Then mark the side edges of the hinge on the back panel. Prop the lid up with scrap pieces of MDF. Pre-drill holes into the back panel. Then attach with screws.
Finishing touches. Add any additional molding as desired. Then finish the top with paint, puttying nail holes as needed.
Install hinges. Installing hinges to support the lid provides additional safety and makes it easier to use. Follow manufacture instructions to properly install your particular hinges. For most, you’ll need to measure for proper placement, mark for screw holes and pre-drill, being careful not through the lid. Placing a bit of painter’s tape on your drill bit to indicate the maximum drilling depth should help with this. Attach the hinges with provided screws.
Your window seat project is complete! Step back and admire your new bay window seating.
Learn how to build a seat cushion for your new window seat here.