Q:

# How do you calculate how many shingles are needed for your building project?

A:

Professional roofing contractors typically provide estimates of materials needed for roofing, including the number of shingles needed. Simple geometric calculations can provide a rough estimate.

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1. ### Calculate the square footage of the roof

Multiple the length times width for every flat surface on your roof, including dormers. Add together all the totals to get the total square footage.

2. ### Divide the square footage by 100

Shingles are sold in "squares," which are 100 square foot sections of roofing. Unless you are applying shingles directly to an already existing asphalt roof, you probably also need the same amount of underlayment. Divide the roof's total square footage by 100 to determine the number of squares of shingles needed.

3. ### Add an extra 10 percent

Add 10 percent to your total to make sure you have enough shingles for trim.

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## Related Questions

• A:

According to builder Mike Guertin in a Fine Homebuilding article, a bundle of roofing shingles contains approximately 33 square feet of shingles. Shingles are sold by the bundle or the square. A square of shingles covers approximately 100 square feet.

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Check with the building project, and plan on how to construct the truss. Measure the size of the roof, and consider the right support and weight of the roof. Determine the roof slope before buying timber panels. Use 2 inches by 8 inches timber panels. Cut the timber panels to fit the roof size before adding a plumb cut at the ends. The plumb cut is a 45-degree angle cut.

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