Drywall Arches: Simple, Segmented, and Elliptical

The simplest arch isn't always the best choice. Here are three options for arched openings
March 10, 2017
3 min read

Arch 1: How to draw a radius arch

Points of reference:

  • Height: top of arch above the floor. All arches in a house will typically share this number. The height will be two inches below the header.
  • Rise: distance from a height down to where the curve begins. For a doorway that is 36 inches wide, the rise will be 18 inches, and the run will be 36 inches.
  • Spring line: where the rise hits the outside edge. Where the curve becomes straight.
  • Run: width of the arch.

Step-by-step guide for drawing a radius arch

  • Mark the center of the opening
  • Draw a plumb line up to the height mark.
  • Measure down 18 inches from the height mark. This Mark will be the pivot point for drawing the radius.
  • Partially set a drywall screw into the pivot point
  • Use a piece of wire to bend to the correct length to draw the radius beginning at the top and swinging the pencil left and right.
  • Draw a level line at the bottom of the arch — the spring line.

That is how to draw the simplest—and least common—arch.

Why is the easiest arch to draw the least used? Because it is hard to make a radius arch look like the other arches in the room if the widths are not all the same. Different spring lines in the same room look like after-thoughts.

A half-circle arch closes off a substantial amount of walking space, causing headache potential.

Arch 2: Drawing a segmented arch

A segmented arch is one that uses a portion of the radius from a larger circle. Segmented arches allow you to keep height and spring line consistent. In this example, the height will be the same as the radius arch was — two inches below the header.

  • Mark the height
  • Determine where the spring line will be (figure the rise). Myron chooses seven inches.
  • Determine what the radius of the segment of the circle will be.

One way is with a construction calculator:

  • Run=36
  • Rise=7
  • Radius = 26-3/4 inches.

Another way is to use the formula:

  • Measure down from the height 26-3/4 inches
  • Partially drive a drywall screw
  • Prebend a piece of wire at 26-3/4 in
  • Swing a line left and right from the center until the line intersects the spring line.
  • This allows you to keep a consistent spring line height with slightly different radii
  • This also provides a definite point of transition from curve to straight.

Arch 3: How to draw an ellipse:

Step by step for drawing an elliptical arch:

  • Measure to find the center
  • Plumb up
  • Mark height
  • Mark the rise (7 inches again)
  • Draw the level spring line
  • Get a piece of string with a knot at either end, 36 inches apart (or whatever the run is).
  • On an elliptical arch, this is called the major axis.
  • Half of 36 is 18 and that is called the minor axis

About the Author

Myron Ferguson

Myron Ferguson, aka That Drywall Guy, points out on his website that over 80% of the visible interior of a home is covered with drywall, and "The bitterness of poor quality remains long after the sweetness of low price is forgotten."
Amen, brother.

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