EPDM vs TPO Roofing
Definition: EPDM and TPO are the two common single-ply membranes for flat and low-slope roofs. EPDM (ethylene propylene diene monomer) is a synthetic rubber, usually black, with seams joined by tape or adhesive. TPO (thermoplastic polyolefin) is a plastic membrane, usually white, with seams heat-welded into one sheet.
Shingles need a slope to shed water. Below about 2/12 (a 2-inch rise per foot), a roof needs a continuous waterproof sheet instead: a membrane. On houses that means porches, additions, dormers, garages and modern flat roofs. EPDM and TPO are the two you will be offered most.
EPDM: the rubber roof
EPDM is a synthetic rubber sheet, sold in thicknesses of 45, 60 and 90 mil and usually black (white EPDM exists and costs more). It comes in very large sheets, so a small roof may have no seams at all; where there are seams they are joined with seam tape or adhesive. It stays flexible in cold weather, shrugs off hail better than most flat-roof materials, and is easy to patch years later. It is what people mean by "rubber roofing".
The disadvantages of EPDM: a black surface absorbs heat, which raises cooling bills under it; glued and taped seams are its weak point and the usual source of leaks as it ages; and it is easy to puncture under foot traffic or falling branches unless a thicker sheet is used.
TPO: the white membrane
TPO is a thermoplastic sheet, typically 45, 60 or 80 mil, with a polyester reinforcing scrim inside and a white, reflective top. Its seams are welded with hot air, so the seam becomes the same material as the sheet and is usually stronger than the membrane beside it. The white surface reflects most of the sun's heat, which is why it dominates in hot climates and on commercial roofs.
The trade-offs: welding needs a skilled crew with the right equipment, so a poor installer shows up at the seams; formulations have changed over the years, so warranties vary more between brands; and patching an old TPO roof is harder than patching EPDM.
Which one to choose
Hot climate, cooling bills, or a roof you can see from upstairs windows: TPO. Cold climate, a roof that will need occasional repairs, or a small roof that can go on in one sheet: EPDM. Both commonly last 20 to 30 years when installed well; the installer matters more than the choice.
What a TPO roof costs
Our quote engine prices TPO at its starter rates: about $8,400–$9,700 for 1,000 sq ft of low-slope roof with the old roof torn off, and about $16,400–$18,800 for 2,000 sq ft, at US-average roofer wages. Insulation boards, new decking and roof edges are on top, and local labour moves it either way. The engine has no EPDM rate, so we do not quote one; ask your roofer for both side by side on the same roof area.