Replacing a flat roof costs $4 to $14 per square foot installed, about $8,000 for an average job, with most projects between $4,000 and $21,000. EPDM rubber runs $4–$13 per ft², TPO $4–$14, PVC $5–$16, modified bitumen $4–$8 and built-up roofing $4–$10. A 1,000 ft² flat roof comes to $4,000–$14,000.
Below: the price of each membrane on a real roof size, what a tear-off adds, what flat roof repairs cost, and when a repair is the wrong spend.
Installed prices, not a quote. Sources are listed at the end.
Price by roof size
| Flat roof area | Replacement cost |
|---|---|
| 1,000 ft² | $4,000–$14,000 |
| 1,500 ft² | $6,000–$21,000 |
| 2,000 ft² | $8,000–$28,000 |
| 3,000 ft² | $12,000–$42,000 |
Per square, the unit roofers use for pitched roofs, that is $400–$1,400. Architectural shingles on a pitched roof run $380–$900 per square, so a flat roof is rarely cheaper per unit of area than a shingle roof; the full shingle comparison is in roof replacement cost.
Price by membrane
| Material | Per ft² installed | 1,000 ft² roof |
|---|---|---|
| EPDM (rubber) | $4–$13 | $4,000–$13,000 |
| TPO | $4–$14 | $4,000–$14,000 |
| PVC | $5–$16 | $5,000–$16,000 |
| Modified bitumen | $4–$8 | $4,000–$8,000 |
| Built-up (BUR) | $4–$10 | $4,000–$10,000 |
EPDM is a synthetic rubber membrane, usually black, and is what "rubber roof" refers to. TPO and PVC are single-ply thermoplastic membranes, usually white or light gray, with seams welded by heat. Modified bitumen is asphalt-based roofing laid in rolls. Built-up roofing stacks layers of asphalt and felt, usually finished with gravel.
The wide range inside each row comes from the same factors that move any roof price: access, the number of penetrations and edges, local labor rates, and the condition of what sits under the old roof. Most flat roofing materials last 15–30 years.
What a tear-off adds
Removing the existing flat roof adds $1–$5 per ft², or about $1,000–$5,000 on a 1,000 ft² roof. The high end applies when several old layers or wet insulation have to come off.
Decking found rotten after the old roof is removed is priced separately, usually per sheet; roof decking replacement cost covers what that adds and how a contract should word it.
Flat roof or shingles
Shingles need a minimum slope. Below the minimum set by the shingle manufacturer and local code, water backs up under the tabs and a membrane is the only option. Where the slope sits close to that line, minimum roof pitch for asphalt shingles gives the numbers, and how to measure roof pitch shows how to check it.
Garage and porch roofs are the most common flat sections on houses; garage roof replacement cost prices both membrane and shingle options for them.
Repair costs
A flat roof repair costs $300–$1,100, about $700 on average:
| Repair | Typical cost |
|---|---|
| Ponding or pooled water | $70–$750 |
| Patch | $150–$1,500 |
| Seam | $200–$1,000 |
| Membrane section | $250–$1,750 |
| Leak | $150–$4,000+ |
Leaks have the widest range because the entry point on a flat roof is often far from the stain inside. Finding it is part of the job; cost to fix a roof leak covers how that is priced.
When a repair is the wrong spend
A patch is worth paying for on a membrane with years of life left and a dry roof underneath. Three signs point to replacement instead:
- The roof is near the end of its expected 15–30 years, and repairs are becoming regular.
- Insulation or decking under the membrane is wet. A patch seals water in, and wet insulation stops insulating.
- Water ponds across large areas for days after rain, which means the surface or the structure has moved.
The same age, extent and deck tests apply as on a pitched roof; see repair or replace a roof.
The short version
- Flat roof replacement: $4–$14 per ft², about $8,000 on average.
- EPDM rubber $4–$13, TPO $4–$14, PVC $5–$16, modified bitumen $4–$8, built-up $4–$10 per ft².
- Tear-off adds $1–$5 per ft².
- Repairs: $300–$1,100, about $700.
- Wet insulation or decking under the membrane means replacement, not a patch.
Where these numbers come from
- Averages, per-ft² ranges by material, costs by roof size, tear-off and lifespan: Fixr, flat roof replacement cost, updated January 27, 2026.
- Repair prices by type: Fixr, flat roof repair cost, updated January 27, 2026.
- Architectural shingle comparison: the price basis used across this site; see roof replacement cost.
- Totals for a 1,000 ft² roof: calculated from the per-ft² ranges above.