How to Expand an Interior Archway

Pry off any trim around the edges of the archway. Cut through the paint at the edges of the trim using a utility knife, and then insert a pry bar between the trim and the wall. Push the pry bar toward the opening in the wall to pull out the trim’s nails.

Measure half of the amount you want to expand the archway’s opening in the wall, marking the distance on the walls on either side of the archway. Draw a vertical line up the wall, using a carpenter’s square, stopping once the lines reach where the old archway begins to curve.

Draw a line that is as long as the new archway will be wide on a piece of cardboard. Draw an arch to connect the two ends of the line using a carpenter’s compass to ensure the arch is symmetrical.

Cut out the arch design you traced onto the cardboard, place it on another piece of cardboard, and then trace around the cutout. Cut along the line you traced, creating a second cutout that is identical to the first one.

Tape the cutouts to the wall above the present archway, lining up the bottom edges of the cutouts with where the current archway begins to curve as well as the vertical lines you drew on the wall. Trace around both cardboard cutouts, transferring the design to the wall.

Pull down both cardboard cutouts. Cut along the lines you traced on the wall using a drywall knife, and then pull off any drywall in the cutout. Cut through the exposed wall studs at the edges of the new archway cutout using a reciprocating saw, and then remove the studs.

Cut wood blocks that are as thick as the hollow gap at the top and sides of the new archway. Spread construction adhesive on the wood blocks, and then slide them into the hollow openings in the drywall, spacing them six inches apart. Drive 1 1/2-inch wood screws through the drywall and into the wood blocks.

Cut strips of drywall that measure the same as the interior of the archway. Wet the backs of the drywall strips until they bend easily, and then lay them against the inside of the archway. Drive wood screws through the drywall and into the wall studs and wood blocks.

Apply drywall tape over any drywall seams. Spread drywall compound over the tape and all of the exposed screw heads. Allow the first layer of compound to dry completely, and then apply up to two more coats of compound. After the final coat of compound has dried, sand the patches with fine-grit sandpaper until they are smooth.