How to Figure Roof Shingle Coverage

Understanding the concept of roof shingle coverage is as important as understanding how many bundles or shingles it will take to cover the roof. Roof shingle coverage is based on the overall length and width of shingles, also known as the exposure. The exposure of shingles is what you can see after the shingles have been installed. When all of the measurements and shingle size have been calculated, you will have determined the number of bundles or squares it will take to roof a house.

Calculate shingle coverage.
  1. Determine the pitch of the roof by using a level and a tape measure. This process is accomplished by placing the level on the roof ridge in a horizontal position, with 12-inches of the level overhanging the roof straight back toward you. Make sure the level indicator in the center of the level is evenly balanced. Measure from the roof up to the end of the level, and take note of it. Do not measure past the underneath side of the level. A measurement of six inches from the roof to the level means that the roof is a 6-12 pitch.

  2. Find the square footage of the roof by measuring the height and length of each separate roof section. Multiply the two numbers together for each section to get the square footage. Add the square footage of all roof sections together to get the total square footage of the roof. Divide this number by 100 to estimate how many squares of shingles you need to cover the roof.

  3. Combine all of the information from steps 1 and 2 together to determine exactly how many squares of shingles you need to cover the roof. Different brands of shingles have specific recommendations on how much shingle is to be exposed, which is based on the pitch of the roof and the length of the shingles. For example, the exposure recommendation for a roof with a 6-12 pitch is that the exposure should not exceed more than five inches for a shingle that is 16 inches long. Put in simple terms, using these estimates: one square of shingles that are 16-inches long, installed with a five-inch exposure, will cover 100 square feet of roof. Divide the total square footage of the roof by 100 square feet to get the correct amount of squares of shingles needed for the job, instead of the estimate in step 2.

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