Drywall Arches

DEAR MIKE: I have a door that divides a dining room and family room. I removed the door and jambs and want to finish the wall as a pass-through opening. My problem is that I want to finish the opening with an arch. I have done some drywall work, but have not done any arches. How hard is this to do? -- Robert B.

DEAR ROBERT: It's not terribly difficult, but it is finesse work. The kind of finesse Michelangelo needed to sculpt stone, except this isn't stone, and you don't need to be Michelangelo.

First, if you haven't already done so, remove the door trim.
There are two ways to do this project. You can buy a prefabricated arch, such as an Insta-Arch (typically between $75-$300 depending on the size), or you can build your own. A prefab arch simply slips into the top of the opening, where it is nailed and then finished.

If you are going to build your own, I would recommend making a template out of cardboard to make sure you are happy with the look. Use this template to cut two arches out of one-half inch plywood.

The plywood arches will sandwich a modified 2X4 to match the thickness of the opening's framing. Assuming your opening was built with 2X4 framing, you will rip a 2X4 down to 2 inches wide. When the plywood is added to either side, the overall thickness will match the opening.
Use the plywood arches as a guide for the length of the 2X4s. Nail one length along the top of the opening, and one length along both sides. Watch the length along the sides of the opening as you don't want them to extend beyond the curve.

Center each 2X4 in the opening and nail them to the framing using 16d nails. Set the plywood arches into place and nail them to the 2X4s you just installed. Your arch is now taking shape.

You're going to install drywall around the arch and along the curve, but the curve is going to need a little extra support. Right now it is a hollow opening, so you need to install some support blocks inside the hollow but right at the edge of the curve.

Cut some blocks to fit in the opening and then nail them or screw them in place. Space them about every 6 inches. To the support blocks you will screw in a piece of Masonite. This is one-eighth of an inch thick and will easily bend along the arch. Cut strips 3 inches wide and follow along the arch. Run the Masonite around the entire opening from floor to floor.

Now all that is left is the drywall work. Fill in the drywall on each side of the opening leaving the underside for last. Trim along the arch with a drywall saw following the curve (it doesn't have to be perfect).

The trick to drywalling along the underside of the arch is getting the drywall to bend. It doesn't like to. If you can find thin drywall, your life will get easier. This thin drywall is designed to bend. Otherwise, you will have to lay strips of inch drywall between a couple of chairs and wet the paper. As the water works on the drywall strip, it will start to sag.

Either method you choose, start about a foot beneath the beginning of the arch and screw the drywall to the blocking around the curve. Finish the lower part of the opening with straight pieces of drywall.

The part of the job that is the most important to the shaping of the arch is applying the corner bead. Use flexible corner bead and push it tightly against the corner of both sides of the opening. Start at one end and run it all the way from floor to floor.
If you have to splice one piece against another, do it along the straight run and not in the arched area. You can attach the corner bead with either a staple gun or drywall nails spaced every 3 inches. Once the corner bead is installed, you can mud it in with three successive coats of joint compound, sanding in between each coat. Finally, texture and paint and you will feel like royalty walking under your arched wall.

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