How to Calculate Shingles for a Metal Roof Installation

Metal roofing was once common on both commercial and residential buildings, but you're more likely to find it topping buildings in rural areas and in certain parts of the south. It is less expensive than shingle roofing, both in labor and material costs. Determining the metal shingles needed to cover a roof before you begin a roofing job will save you time and money; it requires taking several measurements and performing some simple mathematical calculations. Measurements can be taken either on the roof, under the soffit or in the attic; the process is the same for all three.

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Framing square
Calculator

Instructions

- 1
  Measure the length and width of the building, and multiply the two numbers to find its area. Divide this area by the area of the metal shingles you plan to use, to determine how many shingles you would need to cover a flat roof. If your roof is flat, you are now finished; for a pitched roof, you'll now need to perform additional calculations.
- 2
  Mark a point on the soffit. Measure 12 inches from the mark toward the center of the roof, and make another mark.
- 3
  Measure the distance from the 12-inch mark up to the soffit. This distance over 12 is your roof pitch and is used to determine the roofing multiplier. Pitches below 4/12 use a multiplier between 1.15 and 1.25; pitches from 5/12 to 9/12 use a multiplier between 1.25 and 1.4; pitches above 9/12 use a multiplier between 1.4 and 1.7.
- 4
  Multiply the number of sheets by the appropriate multiplier to determine the number of shingles needed to cover a pitched roof.

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