How to Convert to an Arched Doorway

Measure the width of the doorway. Mark the center point of the doorway with a pencil. Mark points on the left and right edges of the doorway where you want the arch to begin and end.

Cut a piece of cardboard according to your width and height measurements to create a template for the arch. Use painter’s tape to tape the cardboard in the doorway. Draw an arch by starting at the left point and connecting the center point, then moving downward from the center point to connect the line to the mark on the right side of the doorway. Mark an X to reference the center point on the cardboard.

Remove the cardboard from the doorway. Draw a line at the center of the arch. Use a utility knife to cut out one half of the arch. Fold the cardboard over and trace the line, disregarding your previous line. This will help ensure that your template arch is balanced. Don’t worry about whether your arch line is perfect at this point. The flexible drywall strip will naturally form an even arch when you attach it in Step 9.

Cut lumber pieces to make the frame for the arch from 2-by-4 inch lumber, according to your width and height measurements. Use a hammer and wood nails to attach the top piece to the pieces for the left and right sides for the frame.

Cut two plywood pieces according to your height and width measurements. Use your cardboard template to draw the arch onto the plywood. Use a reticulating saw to cut out the arch on each piece.

Nail a plywood arch piece to each side of the wood frame piece. Use a drill to mount and attach the plywood arch frame assembly piece inside the doorway using 3 1/2 inch drywall screws.

Measure the length of the arch radius. Make a mark on top of the plywood every 6 inches. Count the marks and use this number to determine how many Masonite strips to cut for attaching the flexible drywall. Next, measure the width between the plywood panels. You will use this measurement to determine the height for the strips.

Cut the Masonite strips, making each strip 2 1/2 inches wide. Attach the strips between the plywood panels with drywall screws.

Follow the manufacturer’s directions for soaking the flexible drywall, if required. Start 6 inches below the curve for the left edge of the arch and fasten the flexible drywall to the door frame, and then continue on, attaching the drywall to the wood blocks inside the archway.

Apply flexible corner beading from the bottom edges of the drywall so that the edges of the arched doorway are seamless. Cover the corner beading with joint compound. Apply multiple coats, if needed, so the framing has smooth edges. Allow drying time between each coat.

Sand the dried edges, and then prime and paint to complete your arched doorway project.