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How to Install a Pre-Formed Doorway Arch

Follow these steps to build a pre-formed arch into a doorway.

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building pre formed arch into doorway

Step 1: Measure the Arch and Mark the Doorway

Pre-fabricated arches come in a set width, typically 48". A piece a plywood or a 2 x 4 may need to be added to adjust the size of your rough door opening to accomodate the arch. Measure the rise (height) of the arch and transfer that measurement to the side walls of the doorway.

Step 2: Set the Arch Into Place

Set one end of the arch at the wall mark and slide the other end into place, then nail the arch into the door frame.

Step 3: Add Reinforcement

To give the arch more strength, screw 2 x 4 blocks into the corners.

add reinforcement to arch

Step 4: Attach Drywall Over the Arch

Lay enough drywall over the arch to make up for the space where the old wall surface was taken out. In this demonstration, 3/4" had to be made up because of the old plaster, so we started with a 1/4" layer and then an additional 1/2" layer over that.

Step 5: Trim Around the Arch

Using the edge of the arch as a guide, trim the drywall along the underside of the arch with a rotary cutting tool.

Step 6: Cover the Underside With Drywall

Cover the underside of the arch with drywall. To prevent the drywall from breaking, spray the drywall piece with water and let it set for 10 minutes to make it more flexible. Using two separate pieces will also help. To attach the drywall, use self-tapping screws to go through the metal form. Use a rasp to finish the edges of the arch (Image 1).

Step 7: Attach the Flexible Corner Bead

Use spray adhesive to attach the flexible corner bead to the edges of the arch. Once this is done, you're ready to patch and paint.