Calculator
Roofing Calculator
Enter the footprint and pick the pitch. You get the real roof area, roofing squares and shingle bundles with waste, and what Chicago requires for your roof type.
Enter the footprint and pick the pitch. You get the real roof area, roofing squares and shingle bundles with waste, and what Chicago requires for your roof type.
A sloped roof has more area than the house footprint. We multiply the footprint (with the overhang) by the pitch factor, the square root of 1 plus (rise / 12) squared. A 6:12 roof is about 1.12 times the footprint.
Roofers count in squares: 1 square is 100 sq ft of roof. Waste covers cuts at hips, valleys and edges: about 10% for a simple gable and 15% for hips, valleys or dormers.
Most shingles come 3 bundles to a square, but check the wrapper. Low-slope roofs use membranes, not shingles, so we show area and squares only.
Chicago rules depend on the roof: on residential buildings up to 4 stories, pitched roofs of 2:12 or steeper can be repaired, recovered or replaced without a permit; low-slope roofs always need one.
Estimates only. Measure carefully and confirm quantities with your supplier or contractor before ordering.
100 square feet of roof surface. A 2,000 sq ft roof is 20 squares.
Rise over 12 in of run. From the attic or a ladder, measure how many inches the roof rises over a 12 in level line. A pitch app on your phone works too.
On residential buildings up to 4 stories, not for pitched roofs (2:12 or steeper) without structural work. Low-slope roofs and other buildings use the Express Permit, and the work needs an Illinois-licensed roofing contractor.
Chicago's Express reroofing covers a recover over 1 existing layer. Going over 2 or more layers needs drawings from an Illinois architect or structural engineer.
Calculators get you close. A free on-site estimate gets you the price. We answer in English and Spanish.
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