UNDERLAYMENT & MOISTURE BARRIER
Roofing Underlayment Calculator
Calculate total rolls needed for synthetic underlayment, asphalt-saturated felt, or peel-and-stick membrane based on net roll coverage.
Roofing Underlayment Calculator
Calculate roll quantities for synthetic underlayment, #15 felt, #30 felt, or peel-and-stick membrane.
sq ft
Underlayment Roll Formula
$$text{Rolls Required} = leftlceil frac{text{Roof Area} times (1 + text{Overlap Factor})}{text{Effective Net Roll Coverage}} rightrceil$$
A standard 10-Square synthetic underlayment roll covers 1,000 sq ft gross, providing approximately 900 sq ft of net coverage after accounting for 4-inch horizontal overlaps and 6-inch end laps.