How to Build a Window Seat

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.

TOH 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.