How to Install Drywall to a Round Archway

Measure from the top of the arch frame down to the arch frame's lowest point. Transfer this measurement to a piece of drywall, measuring across the drywall's width. Snap a chalk line along the drywall's length, at this location. Hold a level against the chalk line. Use the level as a straight edge and cut along the chalk line with a utility knife.

Stand behind the drywall, with one hand on either side of the score line. Gently tap the drywall with your knee, directly behind the score line. The drywall bends into a V shape. Cut along the drywall's paper backing with a utility knife.

Measure the arch frame's width and transfer this to the piece of drywall you cut out in Step 2. Snap a chalk line down the drywall and cut the drywall as before. You are left with a rectangular piece of drywall, which will cover the arch's wooden framework.

Cut out a second piece of drywall, the same length and width as the first piece. Lift one piece up to the front of the frame. Drive drywall screws through the drywall and into the wood frame, both along the top and down the sides. Space the screws approximately 4 inches apart, and sink the screw heads slightly below the surface. Repeat with the second sheet of drywall on the frame's other side. All of the framework will now be covered except for an arch-shaped opening at the bottom, between the two pieces of drywall.

Cut the front piece of drywall with a spiral saw to follow the arch. You will be able to easily follow the arch's curve by feeling the resistance created by the wood frame. Repeat this step on the other side of the arch.

Measure the length of the opening between pieces of drywall. Measure from the left to the right side, following the curve as closely as possible with a tape measure. Note the measurement of the width as well, which is the distance between the two pieces of drywall. Transfer these measurements to a piece of 1/4-inch drywall. Cut the drywall to the desired size with a utility knife, the same way you cut the first two pieces. You will be left with a rectangular strip that will cover the gap between the two drywall pieces already installed on the arch. If the arch is longer than the piece of drywall you have, you may need to combine two strips to fully cover the arch.

Fill a squirt bottle with water and mist the 1/4-inch drywall's paper backing. This makes the drywall bend easier. Position the drywall against the framework underneath the arch. Secure it to the frame using drywall screws.

Cut two flexible corner beads with tin snips to the same length as the arch. Lay one corner bead over the arch's front edge. Secure it in place with drywall screws. Position the second corner bead over the arch's back edge and secure it in place with drywall screws.

Use a 4-inch putty knife to spread the first layer of drywall mud over all the seams, corner beads and drywall screws. Wait two to three hours for this layer to dry. Apply a second layer over the same areas, this time using a 6-inch putty knife. Wait for this layer to dry.

Apply the third and final coat of drywall mud, using a 10-inch putty knife for this coat. Angle the putty knife against the drywall so the coat's edge is thinner than the center. Allow this coat to dry, and then sand everything smooth with a sanding sponge.