LOW-SLOPE & FLAT MEMBRANE

Flat Roof Calculator

Calculate net surface area, penetrations, roofing squares, and single-ply membrane roll quantities for flat and low-slope roofs.

Roof Length

Roof Width

Excluded Area (HVAC Curbs / Skylights)

sq ft

Membrane Roll Size (TPO / EPDM)

$$text{Net Area} = (text{Length} times text{Width}) – text{Exclusions}$$

$$text{Membrane Rolls} = leftlceil frac{text{Net Area} times (1 + text{Waste %})}{text{Roll Coverage (sq ft)}} rightrceil$$

Flat and low-slope roofs (under 2/12 pitch) use continuous single-ply membranes such as TPO, EPDM, or PVC measured in 10-Square or 20-Square rolls.