Almost every new low-slope roof in central Wisconsin is one of three single-ply membranes: EPDM rubber, TPO or PVC. Each one can last decades. Each one can also fail early if it is the wrong choice for the building or is installed without the details a cold climate demands. Here is how they compare.
Quick comparison
| EPDM | TPO | PVC | |
|---|---|---|---|
| What it is | Synthetic rubber, usually black | Thermoplastic polyolefin, usually white | Polyvinyl chloride, usually white |
| Seams | Taped (older roofs glued) | Hot-air welded | Hot-air welded |
| Cold performance | Excellent; stays flexible far below zero | Good when installed to spec | Good; can stiffen with age |
| Grease and chemicals | Poor | Fair | Excellent |
| Typical installed cost | $5.50 – $11 / sq ft | $6 – $12 / sq ft | $7 – $14 / sq ft |
| Typical life | 20 – 30 years | 15 – 25+ years | 20 – 30 years |
EPDM: the cold-climate standard
EPDM has been on flat roofs for decades, and northern states are full of it for good reason. It stays flexible at temperatures well below zero, so freeze and thaw doesn't crack it, and it is easy to repair years later because aged EPDM can be cleaned and primed for new tape and patches. Its weak points are the seams on older roofs that were glued rather than taped, and flashings that shrink away from walls over time. It also doesn't tolerate grease. See EPDM rubber roofing.
TPO: welded seams and a white surface
TPO seams are welded with hot air, so each seam becomes part of one continuous sheet, the main reason it has become the most common new commercial membrane. Its white surface reflects summer heat, which matters on offices, retail and medical buildings that run air conditioning. In a cold climate, TPO wants enough attachment for the wind, good insulation and flashing details that allow for the membrane's movement. Early TPO formulations from the 1990s and 2000s sometimes weathered and cracked sooner than expected; today's are better. See TPO roofing.
PVC: for grease, oils and chemicals
PVC is welded like TPO but resists grease, animal fats, oils and many chemicals. That makes it the right membrane around restaurant exhaust fans and on many food-processing and dairy plants, which central Wisconsin has plenty of. It costs more, so on some buildings the smart move is PVC only where the grease lands. See PVC roofing.
Roof leaking right now?
Wausau Superior Flat Roofing repairs, coats and replaces commercial and flat roofs across Wausau and central Wisconsin, with a written price before any work starts. Request a quote online and we’ll call you back.
What about modified bitumen and built-up roofs?
Modified bitumen is a multi-ply asphalt system, tougher under foot traffic than a single sheet, and common on small commercial buildings, porches and garages. Built-up tar-and-gravel roofs are still on plenty of older schools, churches and plants; they are rarely chosen for new work now but are often recovered or repaired. See modified bitumen and tar and gravel roofs.
How to choose for your building
- Restaurant, food plant or chemical exhaust? PVC, at least around the exhaust.
- Air-conditioned offices, retail or medical? TPO's white surface earns its keep.
- Warehouse, shop or plant with little cooling? EPDM is often the best value and the easiest to repair later.
- Small roof with foot traffic, or a home? EPDM or self-adhered modified bitumen.
Whatever the membrane, the details decide how long it lasts: drainage that gets water off the roof before it freezes, flashings that are tall and well terminated, and edges fastened for the wind. A cheaper membrane with good details will outlast an expensive one installed poorly.