This is a project of turning an existing non load bearing doorway into an archway. I copied an existing archway, so I saved myself
Step 1: Find a Doorway
In this photo there is an original archway (left) and a doorway that was blocked off by drywall (right). I cut out the frame of wood and drywall that previously occupied this doorway. Of course I did this after extensive painting, and will have to paint more.
Step 2: Trace Archway or Draw Original
This step needed two people and two ladders, but anyone more patient and crafty can possibly do this by themselves with some screws and ingenuity.
With each ladder and each person on each side of an archway, one person holds and presses a piece of large scrap drywall against the wall to cover all of the arch. the other person traces the existing arch onto the scrap drywall. Also great to add is a level horizontal line from "beginning" to "end" of arch - horizontal axis, and an plumb vertical line from apex of arch to middle of horizontal axis - vertical axis. I had to redraw this due to a little movement of two people. it may be best to brace the scrap with screws while tracing.
If you are drawing an arch, use a flat surface and be symmetrical. Minor imperfections didnt bother me, I figured I could shave off more drywall or make it up with mud. Also, in an old house there aren't many straight lines.
Step 3: Transferring Arch to New Doorway
Now you have the arch drawn on the scrap drywall. Cut the center arch out and smoth the edges as best as possible. Measure height from the floor to the apex of your existing arch. Go to your new doorway and mark the same height above the center of the doorway. Place your template so its apex matches your mark. You may have a slightly different width, so center the template as best as possible and brace the template to the wall with screws. Trace the template and then remove. Adjust the arch as needed to be wider or narrower. Remember you have to account for variables. Are you removing an existing door frame or sheet rocking on top? what is the thickness of your drywall?
Step 4: Cut It Out
Cut the drywall out. I preserved the arch from the first side to compare to future arches. If you have the doorframe and studs behind the drywall try to remove an inch or so further up inside of the drywall. I had a tough time with the stud in one arch and it may show in the final product.
Step 5: Wood Frame for Arch
Some websites I read up on only used a few wooden supports inside the arch then used a material called masonite to span the gap. I was unfamiliar with the product and didnt have it. I instead made all of my wooden supports flush to each other recessed into the arch. I left a depth of about 1/2 inch between the arch lip and wood. this is so you can add drywall in. I used mostly 2x4's and had a few 1x4's for areas that would have a 2x4 protrude further than my half inch recess.
Step 6: Drywall Arch
To make a flat strip of drywall fit in the arch, you must score the back about every inch and a quarter or half. Make a strip of drywall as wide as the recessed area of you arch. score the back and break so now you have a long flexible strip only held on with on sheet of paper. start at one base of the. arch, screw each segment into the wood, work up to the apex and back down.
Step 7: Corner Bead, Spackle, Paint
You will need corner bead for the arches, and I used metal corner bead for the vertical wall corners. I screwed in the tabs in a few areas along the face of the arch and kept in whatever screws that held. if any didnt get a bite behind the drywall, I tried another spot. I spackle it with one coat, let dry, and went back and just cut off whatever of the plastic tabs stuck out. I sanded, did a second coat, and did a third blend/repair. I won't get into the regular inside and outside corners.
I forgot to take a picture of the flex bead before spackling and painting, but this is the final product.