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Flat Arch

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The Flat Arch from Fast Arch of America

The Flat Arch from Fast Arch of AmericaA Flat Arch is a curve extends beyond the ends of the opening.  It joins the uprights at a sharp, nearly perpendicular angle.  It's often used for wide openings.  We also have Ellipse Arches and Half-Round Arches.

Fast Arch of America makes creating a flat arch a simple process.  It starts with just 3 simple measurements.  There's no computation involved - we handle all of that for you.

When you get your Arch Kit, you'll find two halves to the arch.  Just 12 nails later and you're done.  After you've put in one or two, it'll be easy to put them up in under 2 minutes each.

Of course, at Fast Arch of America we're always ready to do something a little unusual.  Need a really big arch?  Our motto is "Any, Size, Any Shape, Any Time."  Give us a a chance to prove it.



How to Measure and Order a Fast Arch

How to Measure for a Fast Arch









Download our printable (pdf) Arch Measurement Guide.


Measure the actual width of the opening from side to side (as you look through it) of the rough frame opening.

"Flat" and "Ellipse" are usually patterned in 2" increments to allow for adjustment during installation.  This won't affect the appearance of the final product and makes installation much simpler.  In other words, 36-3/4" opening would take a 36" Flat or Ellipse Arch.

Half-Round Arches require a closer tolerance and should be measured to within 1".


This is the measurement between the top or peak of the arch and the lowest portion of the arch.  Other terms you may have heard are the rise, leg, spring, or slope of the arch.

A good rule of thumb for an unspecified drop is to use a 6:1 ratio to the Width.  In this case, a 48" wide arch would have a drop of 8".

The drop of a half-round or half-circle arch should be 1/2 of diameter of the circle,  In other words, the drop of a half-round arch with a width of 72" would be 36"


The measurement of the thickness of the opening or niche (as you look through it).  Usually it's the depth of the framing member. The measurement should be accurate to 1/4".


Will this be an Arch or a Niche.  Arches are passage type openings and Niches have a closed back.  The difference is in the direction of the back flange and the cost is the same.


Flat, Ellipse, Half-round?  Take a look at the various types of Arches to see what styles are available.  Or call us for something unique.

Installing a Flat Arch

How to Install an Eclipse Arch









The Arch Code is written on the throat of each arch and it will tell you the size of the arch.  For example, an Arch Code of 42/8 is meant to fit a 42 inch wide opening and create an arch with an 8" drop.

Installing a Fast Arch is quick and easy:

  1. Get the Drop measurement from the Arch Code.  It's the second number in the code.  Measure down from the bottom of the upper framing member the distance of the Drop plus 1/2 inch.  Draw a squared line across the inside face of the vertical framing member.
  2. Repeat on the opposite side framing member.
  3. Slip the half-arch over the framing members and align the 1/2" tail with the squared line.  Make sure the arch is snugged firmly to the framing members at both the peak and tail.
  4. Insert a screw or drive a nail through the nailing flange near the bottom (indicated as Nail #1 in the illustration).
  5. Again making sure that the half-arch is snug to the horizontal framing member, place a screw or nail through the top nailing flange near the peak (indicated as Nail #2).
  6. Place a third nail or screw at the outermost corner (indicated as Nail #3).
  7. Move to the backside of the opening and repeat the procedure with 3 more fasteners.
  8. Slip the second half-arch over the framing members, aligning the tail with the squared line.
  9. Drive nails or screws at points 4, 5 & 6 (as indicated by the illustration above)
  10. Repeat on the back side.

Important Notes:

  • There may be an overlap or gap of up to 1" between the two half-arches. The final appearance of the arch will not be affected.
  • For even easier installation on wood framing, Fast Arch has designed a double-faced magnetic hammer.  A 3/4" roofing nail can be driven through the arch nailing flange and into the wood with a single stroke.  This tool allows even very large arches to be installed by a single person and speeds installation time.  For more information on this tool and its availability, please call us.

A Gallery of Flat Arches

Clicking on any of the images will bring up a larger version.

If you're looking for something with more curve, explore our other main types of arches: Ellipse Arches and Half-Round Arches.

What comes in an Arch Kit from Fast Arch of America?