2026 flat roofing costs
Flat Roof Cost
Enter your roof area for a 2026 membrane roofing estimate covering material, labor and permit.
A flat roof costs about $5 to $9 per square foot installed in 2026. TPO and EPDM membrane material runs $1.00 to $2.50 per square foot before labor, and a typical 1,500 sq ft flat roof lands between $7,500 and $13,500.
Estimate a flat roof
Low-slope roofs are measured directly, so there is no pitch multiplier to apply.
Estimated total
—
materials + labor + permit
- Materials 66% · $5,460
- Labor 28% · $2,328
- Permit 6% · $500
Material breakdown
| Material | Qty | Cost |
|---|---|---|
| TPO Membrane (60 mil) | 1080 SF | $1,080 – $2,700 |
| Polyiso Insulation Board | 1080 SF | $1,188 – $1,944 |
| TPO Flashing & Accessories | 129.61 LF | $259 – $454 |
| Termination Bar & Plates | 129.61 LF | $194 – $324 |
| 1-in Smooth Shank Electro-galvanized Roofing Nails 244 -Per Box | 5.4 BOX | $27 – $39 |
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TPO, EPDM and modified bitumen
TPO is a white thermoplastic sheet, heat-welded at the seams. It reflects solar gain, which cuts cooling load, and welded seams are the strongest joint of the three. EPDM is black synthetic rubber, seamed with tape or adhesive; it is the most forgiving to install and repair but absorbs heat. Modified bitumen is asphalt-based roll roofing, torch- or cold-applied in two or three plies, and is the most puncture-resistant of the three.
For a house with a flat section, EPDM is usually the pragmatic choice, because repairs are simple and a competent roofer can patch it in one visit. For a large commercial deck in a hot climate, TPO usually wins on energy.
Drainage is the whole game
Flat roofs are never truly flat. Code requires at least 1/4 inch per foot of fall toward drains, and where that slope is missing you get ponding. Standing water is what kills membrane roofs. It works seams, accelerates UV breakdown and multiplies any small puncture into a leak.
If your flat roof ponds after rain, fixing the slope with tapered insulation costs more than a straight membrane swap but is the only durable answer. Re-covering over a ponding deck just buys a few years.