Flat Roof Calculator
Calculate EPDM, TPO, and PVC membrane requirements for flat and low-slope roofs. Sq ft, rolls, seam tape, edge metal.
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Flat Roof Membrane Calculation
Area = Length × Width
Base roof area
Membrane = Area × (1 + Waste%)
Add waste for overlaps
Rolls = Membrane ÷ Roll size (typically 100-200 sq ft)
EPDM/TPO roll sizes vary
EPDM rolls are typically 10-50 ft wide. TPO/PVC come in 10-20 ft widths. Seam tape and edge metal are based on perimeter and seam length. Minimum slope 1/4" per foot.
Reference: NRCA, membrane manufacturer specs
Frequently Asked Questions
EPDM is rubber (black), 25-30 year life. TPO is white/reflective, good for hot climates, 20-25 years. Both are common for flat roofs.
Typically 6-12 inch side laps and 18-24 inch end laps. Waste factor of 10-15% accounts for overlaps and penetrations.