EPDM roofing: what the rubber roof is, how it goes on, and what it costs
EPDM is a synthetic rubber membrane for flat and low-slope roofs, sold in 45, 60 and 90 mil sheets in black, gray or white. It goes on fully adhered, mechanically attached or ballasted, with the seams sealed by adhesive or tape. A 600 sq ft garage roof in 60 mil, fully adhered, typically comes to $6,300.
Anthony Hicks30+ years in construction. Updated November 5, 2026.
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What EPDM is
EPDM (ethylene propylene diene terpolymer, also written monomer) is a synthetic rubber roofing membrane, made mostly from ethylene and propylene. It’s laid in large sheets over flat and low-slope roofs, from porches and garages to commercial buildings.
The EPDM Roofing Association lists it in:
- Three thicknesses: 45, 60 and 90 mils.
- Three colors: black, gray and white.
- Widths from 7.5 to 50 feet.
In the building code it’s a thermoset single-ply roof covering, made to ASTM D4637 or ASTM D5019 (IRC R905.12.2).
How it goes on
| Method | How it’s held down | Notes |
|---|---|---|
| Fully adhered | Glued to the deck or to insulation board | Bonds directly to wood and concrete decks |
| Mechanically attached | Fastened through to the deck | Used on steel decks; special fasteners for weak decks |
| Ballasted | Loose-laid and weighted with stone or pavers | Any deck that can carry the weight |
The seams are sealed with liquid adhesive or seam tape either way. Without ballast, a 60 mil roof system typically weighs under 2 pounds a square foot, membrane, insulation, fasteners and adhesive together (EPDM Roofing Association).
The slope it needs
The code calls for a design slope of at least 1/4 inch per foot (1/4:12, a 2% slope) for drainage (IRC R905.12.1). “Flat” roofs are built with that slight fall, or tapered insulation, so water runs to the edges or the drains.
What an EPDM roof costs
Priced the way a contractor’s estimate is priced: 60 mil EPDM, fully adhered, with the old rubber roof torn off, and 10% over the roof for laps and turn-ups at the edges.
| Roof | Range | Typical |
|---|---|---|
| A porch or small addition, 300 sq ft | $2,750 to $3,800 | $3,150 |
| A two-car garage, 600 sq ft | $5,500 to $7,600 | $6,300 |
| A flat-roofed house, 1,500 sq ft | $13,900 to $18,800 | $15,700 |
Totals include the contractor’s overhead and profit (20%) and the state’s average sales tax. Each range runs from the lower-priced parts of the country to the higher-priced ones. Edge metal, insulation, new decking and drains are extra.
EPDM, TPO and PVC
All three are single-ply membranes with the same 1/4:12 minimum slope, but the code puts them in two groups: EPDM is a thermoset (R905.12), while TPO and PVC are thermoplastics, made to their own standards (R905.13). The TPO guide and the modified bitumen guide price the other flat roofs the same way.
Common questions
How much does EPDM roofing cost per square foot?
About $9.25 to $12.75 a sq ft of roof, 60 mil and fully adhered, with the old roof torn off, overhead, profit and sales tax.
Is an EPDM roof a rubber roof?
Yes. EPDM is the synthetic rubber membrane that “rubber roof” usually means.
Can water sit on an EPDM roof?
Ponded water doesn’t void an EPDM maker’s warranty, the EPDM Roofing Association says, but a roof should still be built to drain, and the code calls for at least a 1/4:12 slope.
Does the old roof have to come off?
Usually it does, but an old roof can stay in place under a new EPDM roof when the membrane maker’s preparation steps are followed and the old roof and deck are sound (EPDM Roofing Association).
How is an EPDM roof repaired?
A cut or tear is cleaned, primed and covered with a patch (EPDM Roofing Association). No heavy equipment is needed.