How to Build a Window Cornice

A window cornice adds a strong dose of architectural character to any room and at the same time conceals mounting hardware for drapes or blinds. If your home already has interesting moldings, you can design the cornice to match; if it doesn’t, let your imagination be your guide. Or follow our lead to build the one pictured here. It hangs on a French cleat mounted above the window and stands out from the wall enough to allow the curtains to open and close easily. Your cornice should be an inch or two longer than the curtain rod, including the finials, to make it easy to install. It should also be deep enough to clear the finials and the rings by 1 inch.

If you choose to buy a window cornice, there are plenty of wood types and finishes, not to mention architectural styles, to choose from. In either case, you’ll never look at your window the same way again.

Download and print a cut list for building a window cornice.

Step 1

Overview for How to Build a Window Cornice

Cut list

Download and print a cut list for building a window cornice.

1×8 poplar front piece: one at 38 inches from long point to long point

1×8 poplar sides: two at 6⅛ inches

1×4 poplar French cleat: one at 36½ inches

1×10 poplar top piece ripped to 8½ inches: one at 42½ inches

3⅝-inch primed-pine crown molding: Cut to fit.

¾-inch primed pine ogee molding: Cut to fit.

Primed-pine cap molding: Cut to fit.

We made the frame of our cornice (not including the top and moldings) 38 inches wide by 6⅛ inches deep by 7¼ inches tall to cover a 32-inch-wide window with a curtain rod that measures 35 inches from finial to finial and stands a maximum of 5 inches off the wall.

Step 2

Build the Frame

Follow the cut list to size the pieces. For the front and sides, make 45-degree miter cuts where they meet; make 90-degree cuts where the sides will meet the wall. Use corner clamps and wood glue to secure the front to the sides, then tack the corners with a pneumatic nailer and 1½-inch brad nails. To make the French cleat, set your circular-saw blade to 45 degrees and rip a 1×4 in half. Sandwich one half of the cleat between the sides, with the cut edge facing the interior of the frame and pointing down, and secure it with glue and brad nails. Position the top flush at the back and overhanging the front and sides evenly; secure it with glue and brad nails.

Step 3

Attach the Molding

Measure the sides of the cornice and cut the crown, ogee, and cap molding to fit, with 45-degree miter cuts at the outside corners and 90-degree cuts where the pieces will meet the wall. Install all the sidepieces with wood glue and ¾-inch brad nails, then measure and miter-cut the front pieces of molding to fit, and install. For the crown, butt the top edge against the overhang before attaching it.

Step 4

Prep and Paint

Fill nail holes with wood filler, let it dry, and sand it smooth. Apply two coats of paint in the same sheen as your existing casing.

Step 5

Install It

Position the bottom of the French cleat above the window with the cut edge facing the wall and pointing up. Level it, then drill and countersink pilot holes into at least two studs. Secure it with 2½-inch wood screws. With a partner, lift the cornice and lower it onto the cleat.