The working
- 1. Footprint2,400 sq ft house + 1.5 ft overhangs2,709 sq ft
- 2. Roof surface2,709 sq ft footprint × 1.000 (Flat (0/12) pitch multiplier)2,709 sq ft
- 3. Squares to order2,709 ÷ 100 = 27.1 squares, + 10% waste (gable roof)29.8 squares
- 4. Installed2,709 sq ft × $4–$10 per sq ft (tpo membrane (flat roof), HomeGuide, Nov 7, 2025)$10,836 – $27,090
- 5. Tear-off2,709 sq ft × $1–$3 per sq ft to remove one layer (HomeGuide)$2,709 – $8,127
- 6. PermitFlat fee, set locally (HomeGuide, Fixr)$100 – $500
- 7. Installed totalSum, rounded to $100 under $10,000 and $500 above$13,500 – $35,500
Prices are published national installed ranges (mostly HomeGuide, updated Nov 7, 2025), the same ones the roof cost calculator uses, for a straightforward re-roof with one old layer torn off. They are not adjusted for your state; the calculator can do that. Decking repairs, access, steep or cut-up roofs and the contractor all move the final price, so get at least two written quotes.
Squares and the materials list come from the same math as the roof calculator, which works them out for your own measurements.
Flat membrane (TPO/EPDM): installed cost by house size and pitch (one storey)
| House size | Flat (0/12) | 1/12 | 2/12 |
|---|---|---|---|
| 1,000 sq ft | $6,100 – $16,000 | $6,100 – $16,000 | $6,200 – $16,500 |
| 1,500 sq ft | $8,800 – $23,000 | $8,900 – $23,500 | $9,000 – $23,500 |
| 2,000 sq ft | $11,500 – $30,000 | $11,500 – $30,500 | $11,500 – $30,500 |
| 2,500 sq ft | $14,000 – $37,000 | $14,000 – $37,000 | $14,500 – $37,500 |
| 3,000 sq ft | $17,000 – $44,000 | $17,000 – $44,000 | $17,000 – $44,500 |
How it compares on the same 2,400 sq ft house
| Material | Per sq ft | Per square | At Flat (0/12) |
|---|---|---|---|
| Standing-seam metal | $9–$16 | $900–$1,600 | $27,000 – $52,000 |
| TPO membrane (flat roof) | $4–$10 | $400–$1,000 | $13,500 – $35,500 |
| EPDM rubber (flat roof) | $3.50–$10 | $350–$1,000 | $12,500 – $35,500 |
| Modified bitumen (flat roof) | $4–$7.50 | $400–$750 | $13,500 – $29,000 |
Only materials the 2024 IRC allows on a low-slope roof (¼/12). Per-foot prices are installed, before tear-off and permit; the last column includes both.
Did hail hit your area? Insurance often covers hail damage. Check hail history for your city, with storm reports back to 1955.
Questions people ask
How much is a flat membrane (tpo/epdm) roof per square?
About $400–$1,000 per square (100 sq ft) installed for tpo membrane (flat roof), before tear-off and permit (HomeGuide, Nov 7, 2025).
What does a flat membrane (tpo/epdm) roof cost on a 2,400 sq ft house?
About $13,500 – $35,500 for a one-storey house at Flat (0/12), including removing one old layer and a permit.