How to Build a Window Seat

As attractive as window seats are, only a few older homes with deep dormers seem to have them. And adding a window seat has always been considered impractical. First, you need a niche that features a window. Then, the seat has to be custom-built by a cabinetmaker or trim carpenter to fit the exact width and sill height of the window. Not surprisingly, this approach is expensive and time-consuming.

Here’s how to build a beautiful, custom window seat in just a couple of days using ready-made kitchen cabinets. This simple, do-it-yourself approach provides both the “niche” and the window seat, and an abundance of storage space. This seat was built under a 6-foot-wide kitchen window, but its design can easily be adapted for any size window in almost any room. The seat is made up of six kitchen wall cabinets and two 48-inch-tall bookcase units, which are trimmed with decorative crown molding. The window seat itself is composed of two 15-inch-tall, over-the-refrigerator cabinets set side-by-side.

Step 1

Build the Toekick

Start by building a perimeter base, called the toekick, out of 2x4s or 2x6s to the same height as the existing baseboard. The depth of the toekick must equal the depth of the cabinets, not including their doors. Fasten the toekick together with 3-inch screws; check to make sure it’s level. Anchor the toekick with a couple of screws driven into the floor or wall studs.

Tip: When deciding where to install a window seat, keep in mind that most windows have an air register or baseboard heater below them. (This one did not.) To ensure that the window seat does not block the flow of heat into the room, you must extend the ductwork under the seat and mount the register in the front of the toekick base. For a hot-water heating system, have a heating contractor install a flat toekick radiator with electric blower under the window seat.

Step 2

Begin the Assembly

Begin the assembly by setting the two over-the-refrigerator cabinets onto the toekick. Center the two units under the window, then clamp them together with their face frames perfectly flush.

The cabinets used here feature solid-maple raised-panel doors, concealed hinges, and a honey-tone Spice Maple finish. The total cost of all the cabinets and prefinished molding was around $1,700. If that’s a budget-breaker, you can save up to 40 percent by using plastic-laminate cabinets or oak cabinets with recessed, flat-panel doors.

Step 3

Fasten the Cabinets

Drill through the first face frame and partially into the second one with a countersink drill bit. Be sure to drill deep enough so that the screw heads are flush with the surface. Fasten the cabinets together with two 2½-inch drywall screws.

Step 4

Install Cabinets to Toekick

Next, install a 12-inch-deep x 24½-inch-tall x 30-inch-wide cabinet to each end of the toekick. Clamp and screw these end cabinets to the window seat cabinets. Again, be sure the face frames are perfectly flush before driving in the screws.

Step 5

Level and Secure End Cabinets

Check each end cabinet with a level, then secure it to the wall with two screws driven into wall studs. If necessary, place shims behind the cabinets to prevent the screws from pulling them out of alignment.

Step 6

Fasten Blocks to Add Height (if Needed)

The end cabinets are topped with 15-inch-tall intermediate cabinets, which then receive the bookcase units. However, before proceeding, fasten six 3½-inch-long 2×2 blocks to the top of each end cabinet. These blocks raised the overall height of the cabinets so that the bookcases reached the soffit above.

Step 7

Fit All Components Together and Install Bookcases

Continue the assembly by setting the intermediate end cabinets on top of the end cabinets and screwing them to the wall. Next, install the bookcase units by first clamping them to the intermediate cabinets, and then fastening them with 2 ½-inch screws driven through the face frames.

Step 8

Conceal the Joints

To create the look of a custom-made window seat, it’s important to use matching prefinished moldings and accessories, which are sold by the cabinet manufacturer. Start by concealing the joints between the three cabinets on each end with prefinished plywood skins. Cut the skins to length, then attach them with contact cement.

Step 9

Install Waist-Band and Baseboard Molding

Next, nail the waist-band molding along the joint between the end cabinets and the intermediate cabinets. This narrow piece of trim covers the large gap created by the 2×2 blocks. Install baseboard molding around the bottom of the cabinets to hide the rough toekick. If the molding is too tall, rip it down to the proper width on a table saw.

Step 10

Install Finishing Crown

Nail 1½-inch crown molding along the tops of the cabinets. If small spaces remain above the molding, fill them with caulk. Finally, replace the cabinet doors, install the adjustable bookshelves and set the upholstered cushion onto the window seat cabinets.

Finally, need an upholstered, foam-rubber seat cushion. This expense will vary depending on the size of the cushion, the fabric you select, and the quality of the foam.