An arch is a classic design that can be traced back to ancient Rome. In addition to its aesthetic beauty, its elegant curves also served a practical purpose by helping to support the surrounding structure. If arches are a feature you would like to have in your home, you can build them out of drywall and timber.
Strip the drywall away from the interior edges of the entryway to get down to the frame.
Cut a 2-by-4 board that fits the length of the top of the entryway, then cut two 2-by-4 boards to the same length to be the sides of the arch.
Nail the two side boards to the ends of the top board to form a "U".
Cut two sheets of 1/2-inch plywood that are identical to each other. The top and sides of the plywood sheets must match the top and sides of the U-frame. The fourth side is the arch. The arch can take any shape you want, but it must be the same on both plywood sheets.
Screw the plywood sheets to the outer edges of the wooden U frame, positioning the sheets so that the arched end is over the open end of the U frame. Use drywall screws to attach the plywood, and drive the screws deep enough that the heads are slightly below the surface of the plywood sheets.
Place the arch into position in the entryway with the help of an assistant. Connect the arch to the frame of the doorway with drywall screws.
Measure the space between the inside edges of the plywood sheets and cut blocks out of a 1-by-2 board that match the distance. You need enough blocks so you can install them every 2 inches inside the bottom edge of the archway.
Place the blocks along the bottom of the arch and attach them with drywall screws.
Measure the length and width of the arch's bottom edge and cut a piece of 1/4-inch drywall to fit.
Dampen the drywall with a spray bottle until you can bend it without it cracking.
Install the drywall along the bottom edge of the arch with drywall screws.
Cover the edges of the arch with flexible corner beads, stapling them to the arch every 3 inches.
Cover the plywood and the drywall on the bottom of the arch with joint compound. Smooth the surface of the joint compound with a 12-inch putty knife. Allow the joint compound to dry for the time specified on the packaging.
Apply a second coat of joint compound to the archway and allow it to dry, then add a third coat and allow that to dry.
Sand the surfaces of the archway with a fine-grit sanding block or sandpaper until it's smooth, then wipe the dust off with a dry rag.
Cover the surfaces of the archway with primer and allow it to dry.
Paint the surfaces of the arch with paint that matches the rest of the walls and allow it to dry. Add a second coat of paint, then allow that to dry.
Wear safety goggles when you're sawing the wood.