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Re: building an arched doorway

From: info@builderswebsource.com
Category: Carpentry and Framing
Remote Name: 63.198.181.43
Date: 20 Jan 2001
Time: 09:47 AM

Comments

Based on your existing rough opening dimensions of 52" wide by 8' high, building an arched doorway frame is easy.

Cut two pieces of 1/2" plywood 52" wide by 27-1/2" high. (This assumes the dimension you gave above are precise).

Mark a center line on each piece of plywood (26") along the short axis. One at a time, lay each piece of plywood on a scrap piece of remaining plywood. Put a nail into the scrap piece of plywood and line it up with the bottom of each cut piece along the center line. This nail will act as the rotation point for a makeshift compass.

Tie some string to a sharp pencil and make a loop on the other end, placing it over the head of the nail. The total length of the string from nail to center of the pencil tip should be 26", which is the desired radius of the arch. (The radius is one-half the width of the rough opening)

Keeping the string tight, start at the left-hand bottom side of the cut plywood and draw an arch, rotating a full 180 degrees clockwise with the pencil. If you do this correctly, the top of the arch should leave a 1-1/2" clearance to the top of the plywood. This extra space will be used to nail 2x4 supports. Carefully cut out along this pencil line with a jig saw.

Perform the same procedure with the 2nd piece of plywood. Now you'll have two pieces of plywood forming the shape of the arch.

Determine the thickness of the existing rough wall, subtract the thickness of the two plywood pieces and cut several pieces of 2x4 to make up the difference, nailing them in an arched fashion. You will also need some nailers along the top and sides of the arch to attach to the existing header and jack studs supporting the rough opening. For example, suppose the existing rough opening is made from 2x4's with a 3-1/2" depth. Next, suppose you are using 1/2" plywood. This means you need to cut 2x4's to a length of 3-1/2" - 2*(1/2") = 2-1/2". These will be used to give structure to the arch between the plywood pieces.

Once nailed into place, the result will give you an arched opening...which can now be covered with sheetrock or framed in to accommodate a door.

Now, if for some reason you don't want the arch to be a full semicircle, then you can create a more gentle arch by making a longer center line and placing your nail in a different location. You can experiment until you achieve the desired shape.

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