Formula
Waste is added before the area is divided into squares:
squares = sloped area × (1 + waste / 100) / 100
The pitch page finds sloped area from a footprint. This page starts after that area is known. Bundles are on the shingle page.
Assumptions
- The area is the sloped surface, not the flat footprint.
- One square is 100 square feet.
- One waste percent covers the whole roof.
Worked example
1,800 square feet of roof with 10% waste is 19.8 squares.
Input definitions
- Square
- 100 square feet of finished roof surface.
- Waste
- Extra surface for hips, valleys, and cuts.
Limitations
Starter strips, ridge cap, and underlayment are not converted into their own squares.
Questions
What if I only know the footprint?
Use the roof pitch page to get the sloped area, then return here.
Does a square include waste already?
Only the waste percent you type. A product sold as a square still needs that extra if you enter it.