An arch in an interior wall can add style and sophistication to any room's decor The most common place to install this arch is within a doorway. This will require removing the existing casing, jambs and moulding. Once the area is prepped and ready, you can start making the arch. To accomplish this, you will need to purchase an appropriately sized prefabricated arch, which will include the top of the arch and the side pillars.
Measure the length of the existing space where you want to make the arch. Use this measurement to purchase the prefabricated archway pieces.
Cut two identical pieces of drywall that are the same length that you measured and tall enough to install your prefabricated arch. Use a drywall saw. If you're not making an arch in a doorway, cut out the edges of the existing drywall, as the new drywall pieces on either side fit flush with the wall.
Install one piece of drywall over the area using 1.4-inch drywall screws. Install the second piece on the opposite side of the space.
Trace the shape of the arch onto the drywall on both sides. A cardboard cut-out can help ensure the arch is even on each side of the drywall. Use the prefabricated archway pillars and top arch piece as a guide.
Use your drywall saw to cut out the shape of the arch that you traced on both sides.
Hide seams between the old and new drywall by applying drywall tape and then covering the tape with joint compound.
Wait for the compound to dry and apply primer. Once the primer is dry, apply paint to match the colour of your wall. Wait for it to dry, as well.
Slide the prefabricated archway pieces into place. You will need to install two side pillars and a top arch piece. Attach the pieces to the surrounding area with 2 1/2-inch finishing nails.