How to Build a Window Bench with Storage

Instructions

1. First and foremost, wear proper personal safety equipment when using any power tools.
2. Remove any baseboard from the bay window.
3. Determine the height of your bench. If you are adding a cushion you’ll want to reduce the frame height by 2″ plus the height of your seat board. We settled on a finished height of 20″ including the cushion. Therefore, the math to figure out the height of the frame is 20″ – 5/8″ – 2″ = 17 3/8″.
4. Mark the height of the frame at several points along the walls. Then use a level to draw a line around all three walls of the bay window. You may not hit the marks you’ve drawn, but it could be that your floor isn’t level. That’s ok because the goal is to make the top as level as possible.
5. Using a stud finder, locate all of the studs in the bay window and mark them above the line you’ve just drawn.
6. Measure and cut a piece for the center wall with the proper angles to match the wall on either end. For example, if your wall angle measures 135°, then each end should be cut at 45° (total of 180°). Screw into the studs using 2.5″ screws.
   
7. Then measure the length from the piece you just installed to the outside edge of the wall. Deduct 2″ for the depth front span piece, 1/4″ for the plywood face and 5/8″ for the trim you will be attaching later. Cut each end using the same angle you used in the previous step, but they will both be cut in the same direction as shown in the diagram below.
   
8. Measure and cut two 2″ x 4″s to fit in the corners for added support at the back. Screw into studs using 2.5″ screws.
   
9. Measure from one end to the other and cut a 2″ x 4″ to length for the front span. You can add angled ends to match the wall, however, I just left ours at 90°. Attach to the side supports using 2.5″ screws.
   
10. Measure from the bottom of each side of the front span to the floor and cut two 2″ x 4″s to these measurements. Drill two pocket holes on one end of each. If you don’t have a Kreg Pocket Hole System from The Home Depot (which we couldn’t live without now that we have one) you can simply toenail the screws instead of using pocket holes. Secure to the bottom of the front span using 2.5″ pocket hole screws. Then, measure the length along the floor between the two end pieces. Cut a 2″ x 4″ to length and drill two pocket holes on each end. Secure to the end pieces using 2.5″ hole screws.
    
11. Find and mark the mid-point of the front spans. Measure the distance between the top and bottom and cut a 2″ x 4″ to that size. Drill two pocket holes on each end of the board. Secure in place with 2.5″ pocket hole screws. Then find and mark the mid-point between the center piece you just attached and each side of the bench. Measure, cut, drill and attach these pieces the same way you did the center piece.
    
12. Measure from the back corners to the top front span. Cut two pieces of 2″ x 4″ to fit and drill two pocket holes on one end. Insert and square them up as shown below and use 2.5″ pocket hole screws to secure the back and drill through the front span with 2.5″ construction screws to secure in place.
    
13. Measure between the two pieces you just installed. Cut a 2″ x 4″ to size and secure to the back of the frame with 2.5″ construction screws.
    
14. Cut a 2″ x 4″ to fit the front area between the side supports. If your bench is square it will likely be the same length as the board you installed in the last step, but measure again just to make sure. Secure it with the 2″ side against the front span with 2.5″ constructions screws. Then measure for the pieces that run front to back on each side. Drill pocket holes on one end of each board and screw in place using four pocket hole screws and three construction screws along each side as per the diagram below.
    
15. Cut the 24″ x 48″ x 1/4″ plywood sheets down to size. We used two panels and joined them in the center where they will be covered with trim, but you can buy a single 4′ x 8′ x 1/4″ sheet and cut it down to fit if you prefer (24″ x 48″ sheets fit better in a car). Using an air compressor and brad nailer, secure the panels to the front frame using 1 1/4″ brad nails. Nail in places that will be covered by the final trim so that you don’t have to fill as many holes.
    
16. If you are going to attach baseboard trim to the bottom of your bench, you will need to bump it out by 5/8″. Cut a piece of scrap 5/8″ plywood to the height and length of your baseboard and attach them to each other with brad nails and glue. Then add a 1″ x 4″ MDF board on top of it, and another one at the top of the bench using glue and brad nailer with 1 1/4″ nails.
    
17. Add the baseboard back to the bottom, and then cut three 1″ x 4″ boards for each side and the center to cover the seam of the plywood. Use brad nails and to secure them to the front. NOTE: If your bench is really wide, you can also divide the two boxes to make a total of 4. Simply cut two more 1″ x 4″s down to size and center them in each of the boxes.
    
18. There are two ways to complete this next step. If you do not want to use the bench for storage, you can simply cut a single piece of 5/8″ plywood to fit the seating area and add a piece of decorative 5/8″ trim to the face edge to finish the look. Or, you can add hidden storage as we did. This part will be a bit of a jigsaw puzzle. The way we did it was to first attach the front lip piece to ensure that the front was square. This front lip made it possible to hide the seams of the lid. It’s a 1″ x 4″ MPF piece that we made overhang the front by 1/2″. We added angles on the edge of this piece to match the angle of the wall to give it more of a finished look. Secure it with glue and brad nails. We then cut the sides of the seat out of the MDF shelf board. There are a couple of ways to do this.  You could trace a template on a large piece of paper and then transfer it to the wood. The other method is to measure the length from the wall to where the side supports are located at the front edge (along the inside of the front lip piece). You don’t want to cover all of the side supports, only about half of it. The other half will support the lid when it is closed. You can also use an angle finder (or if you don’t have one, attach two 2″ x 4″s at one end with one screw so that you can open it up like a big angle finder). Place one board along the front lip piece, and rotate the other to match the angle of the wall. Hold the angle of the 2″ x 4″s and transfer to your wood. Cut it out carefully using a circular saw. Cut a piece of plywood or MDF using a jigsaw for the back piece that runs against the wall. The goal is to create an absolute square hole for the lid to fit in. If your back wall isn’t straight or the top is not exactly square, then this is where you will make adjustments. You’ll also want to make sure that some of the supporting 2″ x 4″ will still be visible so it can shoulder some of the seat weight.
    
19. Install the piano hinge to the front of the back 5/8″ piece you just installed with the hinge facing up. Be careful to attach it in the correct orientation so that your lid swings upwards. Measure the opening for the lid. Reduce each side by 1/8″ to give it some clearance. Cut the lid out of your shelf board or plywood. On the face side of the lid, drill a 7/8″ hole in the center about 2″ from the front edge. This will be how you will lift the storage lid. Make sure you do this before you test the fit of the lid, or else you’ll have a hard time removing it again. Once you’ve tested it for fit you’ll want to have someone help you hold the lid up on an angle so that you can attach the hinge to the back edge of the lid.
    
20. Caulk around all seams and edges, except for the lid. Fill the brad nail holes with wood filler. Allow to dry and then paint with your trim color. If you have larger than normal gaps around the wall, you can use cover trim like we did to cover the spaces and give it a more finished look.
    
21. Find someone to make you a cushion! We didn’t even attempt this on our own. We had a local upholsterer make us one for under $200! These can get quite expensive so make sure you shop around.