Roofing is priced in squares. Understanding squares and waste makes any roof estimate or roof report easier to check.
What is a roofing square?
One roofing square covers 100 square feet of roof surface. A 2,800 square foot roof is 28 squares.
How to convert
Divide the roof area in square feet by 100. Measure the sloped roof surface, not the footprint of the house. A steeper pitch means more surface for the same footprint.
What is waste factor?
Shingles are cut at hips, valleys, rakes and eaves, so you order more than the measured area. That extra is the waste factor. Ten percent is common on simple roofs, and fifteen percent is common on roofs with many hips, valleys or dormers.
Example
A 28 square roof with a 10% waste factor needs 28 × 1.10 = 30.8 squares of shingles. The removal quantity stays at 28 squares because you only tear off what is there.
Where it appears in an estimate
Waste applies to the new materials line. Tear-off, felt and labor lines usually use the measured area. Our order form lets you choose a 10% or 15% waste factor.
Next: the roof estimate checklist.