How to Cut a Door Archway

Measure the doorway's opening along the top. Transfer this measurement to a 2-by-3-inch board. Cut the board to the appropriate length with a circular saw.

Determine how far down the doorway's sides you wish the arch to start (generally 12 to 18 inches). Transfer this number to another 2-by-3-inch board and cut the board to length with a circular saw. Cut another 2-by-3-inch board to the same length as the previous board.

Place the two side boards underneath the top board's ends to form half a rectangle. Nail the two side boards in place with 2-inch nails.

Draw the arch's dimensions onto a piece of cardboard (it will look like a half circle). Cut the half circle out of the cardboard with a scissors. Lay the half circle onto a piece of 1/2-inch plywood. Line up the half circle's straight edge with the plywood's bottom edge. Trace around the half circle with a pencil. Repeat this step on a second piece of 1/2-inch plywood so you have two half circle tracings.

Cut the half circles out of the 1/2-inch plywood with a jigsaw. Lay one half circle over the rectangular frame. Drive 1 1/4-inch screws through the plywood and into the frame using a drill and Phillips driving bit. Space the screws approximately 3 to 4 inches apart. Flip the frame over and repeat this step to secure the second half circle on the other side.

Lift the frame into the doorway. Line up the plywoods' surface with the wall surface. Drive 3 1/2-inch drywall screws through the frame and into the doorway. Space the screws 3 to 4 inches apart.

Measure the distance between the two pieces of plywood. Transfer this measurement to a 1-by-2-inch board. Cut the board to the appropriate length with a circular saw. Cut more of these short pieces until you have enough to space them every 2 inches along the arch's curve.

Position the short pieces between the plywood pieces, spaced 2 to 6 inches apart, depending on the arch's curve (tighter curves require closer short pieces). Secure the short pieces with 1 1/4-inch screws. Move to the frame's other side and secure the short pieces.

Measure the frame's length and width. Transfer these measurements to a new 1/2-inch drywall sheet. Use a level as a straight edge and cut along the pencil lines with a utility knife. Break the drywall along the score lines and cut through the paper backing. Repeat this for the frame's other side so you have two rectangular pieces of drywall.

Lift one of the drywall rectangles up to the frame. Secure it with 1-inch drywall screws. Repeat with the second drywall rectangle on the frame's other side. Cut the drywall rectangles to follow the arch using a spiral saw. Follow the frame's resistance as you cut.

Measure the doorway's thickness. Transfer this measurement to a piece of 1/2-inch drywall and cut it. Measure the door opening's width, following the arch's curve as closely as possible. Transfer this measurement to the same drywall strip. Cut the strip to the appropriate length.

Lay the strip face down between two sawhorses. Moisten a sponge with water and wet the strip's backside. Continue to moisten it periodically for the next hour or until the strip begins to sag in the middle. Lift the strip up to the frame's underside. Use 1-inch drywall screws to secure it to the short 1-by-2-inch boards.