Building an arched doorway can be a very satisfying do-it-yourself project. Building an archway requires a little geometry and patience, but the rewards and skills gained usually make the project worth the effort. Archways can be built in a number of ways, but today we will overview a few common arch designs and the basic steps to build them.
Step 1: Define the Arch (Hexagonal, Half Circle, or Oval)
The first step is to define your arch. How tall and wide will the arch be? Generally, you will want to define the shape of the arch based on the width of the opening. For example, let’s say our doorway is 36” wide, which is common. Next, you’ll want to decide which style of arch to build.
Hexagonal arches are a great way to add visual interest to an otherwise simple doorway. Hexagonal arches use four 45 degree angles to turn 180 degrees instead of two 90 degree angles. Hexagonal arches are simple for new DIYers to build because most tools, like circular saws and miter saws already have 45 degree settings.
Half-circle arches are very elegant looking and add contrast to all of the sharp, straight lines that often surround them. Half-circle arches look impressive, but they are actually one of the easiest to build. If you know the width of the doorway, you can lay out the arch using a nail, piece of string, and a pencil.
Half-circle arches are typically added to standard doorways because doing otherwise will involve the modification of the header and possibly the studs. For example, a 36” wide doorway will accommodate an 18” half-circle arch (36/2=18), and be 80” from floor to ceiling. If our ceilings are standard height, which is typically 96” (8’), we quickly see that we only have 16” above the doorway, but we need 18” for the half-circle arch.
Oval arches are probably the most impressive looking of all. Oval arches have the huge advantage of working with almost any size doorway. Oval arches are more complex to design and transfer to the material, but the results can be amazing. Some open floor plan home designs use very wide arched doorways to separate rooms instead of solid walls.
Step 2: Installing the Backing
In this method, you will be installing a backer to give your arch something to connect to. The shape will change of course, depending on which arch design you are using, but the function will remain the same. Most pros use a combination of lumber and oriented strand board (OSB). The backer is what you will install your drywall and corner bead onto.
If your wall thickness is 4 ⅝”, which is standard, you can rip your lumber to 2 ⅝” and install it inside the existing doorway, exactly in the center. Next, you will need the OSB or plywood cut in the shape of your arch. A great technique is to cut your first one, and if it fits, use it as a pattern for the other side.
At this stage you should have the lumber and OSB or plywood installed, leaving approximately ½” between the edge of the existing doorway and the OSB. If the measurement is less than ½”, you’ll need to move the backer closer to the center or the new drywall will protrude from the wall.
Step 3: Install the Drywall and Corner Bead
You can use the pattern you made earlier to transfer the pattern to the drywall. When cutting out any pattern in drywall, the pros use a sharp blade to simply cut the paper along the line. With pressure, the drywall will break off along the cut. You may need a rasp or rough sandpaper to clean the edges.
Now you are ready to install the drywall. The pros use drywall screws because they make a convenient divot and can be easily removed. However, keep the screws one inch away from the outer edge so as not to interfere with the corner bead.
Once the panel is screwed in, the corner bead can be notched or bent as needed to form the outside corner. If you are building a half-circle or oval arch, use a vinyl arch corner bead. If building a hexagonal arch, use metal, paper backed metal, or vinyl corner bead.
Corner bead is usually installed with #6 drywall nails, but screws can also be used. Just make sure the screw head is recessed below the paper. All corner bead has a slightly raised edge, which allows the finisher to smooth the compound over the corner bead. The edge also defines the corner and protects it from impacts.
Step 4: Finishing
After everything has been secured you are ready for the finishing. Finishing involves applying drywall compound (known to the pros as mud) to the blemishes caused by the installation. Joints and fastener holes are covered by drywall compound, allowed to dry, and lightly sanded. The goal is to effectively hide any joints and fastener holes so that with paint, they cannot be seen.
You can either mix your own drywall compound, or buy it ready mixed. You may want to do a little research and decide which drywall finish you prefer. For example, if you want a duller finish, like with sanded paint, you can use the drywall compound pretty much as is.
However, if you plan a semi-gloss paint covering, you’ll want to thin down the compound for a smoother texture. You’ll probably need more coats using the thinned compound, but the texture you can achieve is remarkable. Generally speaking, the more time you spend at this stage, the better the project will look.
To make the job easier, you will need to remove the old corner bead from the old doorway and replace it with drywall tape. Corner bead can be removed relatively easily with a small pry bar, but the job will be messy, so use drop cloths. After the old corner bead has been removed, you can apply the drywall tape in its place and apply drywall compound.
The last step is to skim coat all of the new tape and fastener holes, so use a 10” drywall knife (or wider) when possible. Using a wide drywall knife makes smoothing easier by smoothing the compound over a wider area. Most projects will require at least two coats of drywall compound, but some may need more, with sanding in between coats. Once the last coat of drywall compound has dried completely, it can be dry or wet sanded and primed.