Flat Roof Cost Calculator
Calculate flat roof costs by material and area. Compare TPO, EPDM, modified bitumen, and PVC systems.
How It Works
Enter roof area
Measure the total flat or low-slope roof area in square feet.
Select membrane type
Choose TPO, EPDM, modified bitumen, PVC, or built-up roofing.
Add tearoff & insulation
Old membrane removal and new insulation board are common add-ons.
Frequently Asked Questions
How much does a flat roof cost?
Flat roof installation costs $4–$13 per sq ft depending on material. TPO (thermoplastic polyolefin) costs $4–$8 per sq ft and is the most popular. EPDM rubber costs $3–$7 per sq ft. PVC costs $6–$12 per sq ft and offers the best chemical resistance. Modified bitumen costs $4–$8 per sq ft and is a proven multi-layer system.
What is the best flat roof material?
TPO is the most popular choice due to its balance of cost, durability, and energy efficiency — white TPO reflects heat, reducing cooling costs. EPDM (rubber) is durable and budget-friendly but less energy-efficient. PVC is best for roofs with kitchen exhaust or chemical exposure. For low-slope roofs in moderate climates, TPO or EPDM typically offer the best value.
How long does a flat roof last?
Flat roof lifespan varies by material: TPO lasts 15–25 years, EPDM lasts 20–30 years, PVC lasts 20–30 years, and modified bitumen lasts 15–20 years. Proper installation, drainage, and annual maintenance (clearing debris, checking seams and flashing) significantly extend lifespan.
Do flat roofs need drains?
Yes — all flat roofs need a drainage system. Options include interior drains (most effective, requires piping), scuppers (openings in the parapet wall), and gutters with a slight slope (2% minimum). Poor drainage is the leading cause of flat roof failure. Budget an additional $500–$3,000 for drainage depending on roof size and system type.