TPO, PVC and EPDM compared
| Membrane | Installed cost per sq ft | Lifespan | Warranty we usually give | Best for |
|---|---|---|---|---|
| TPO white, our most installed | $8.50 to $13.50 | 15 to 20 years | 20 years, materials and labor, on a full tear-off | Most standard commercial roofs, including churches |
| PVC white, premium | $9.50 to $14.50 | 20 to 25 years | 20 years, materials and labor, on a full tear-off | Restaurants, rooftops with heavy HVAC equipment, and any roof that sees grease, oil or chemicals |
| EPDM rubber, proven track record | $8.25 to $12.50 | 20 to 25 years | Ask us | Tight budgets and roofs with little equipment on them |
Most flat roofs we replace get TPO. It costs less than PVC, it’s white, so it reflects the sun instead of soaking up heat, and the seams are heat-welded. PVC runs a dollar more per square foot at both ends of the range, and it earns that on restaurants and on roofs crowded with equipment. We install all three membranes, and we prefer TPO and PVC. On a full tear-off we can usually give a 20-year materials and labor warranty on either.
What decides how long a flat roof lasts
The install decides it more than the membrane does. A flat roof is a stack: the deck, insulation on the deck, the membrane on top, and seams, flashings and drains tying it together. Get one layer wrong and the whole roof gives out early, whichever membrane is on it. These are the parts worth checking on any bid, ours included.
Membrane thickness
We use 60 mil membrane, which is 0.060 inches thick. A bid on 50 mil saves about $10 to $20 per square (a square is 100 square feet), so on a 120 square building, 12,000 square feet, the saving is $1,200 to $2,400.
“It’s not enough of a cost difference to try and push the lower product.”
Insulation to code
Indiana code calls for R-20 insulation under a commercial roof, roughly 4 inches. Michigan calls for R-30, roughly 5 inches. A bid that comes in well under the others may have skipped that upgrade. If the deck is dead flat, tapered insulation gives the roof about a quarter inch of fall per foot toward the drains, so water leaves instead of sitting.
The deck you can’t see yet
Nobody sees the deck until the old roof comes off. Bad sheeting found during tear-off is the one thing that can change our price. If we find it, we stop, document it and talk it through with you before any extra cost goes on.
Before the membrane
Membrane on
Which membrane fits your building
Match the membrane to what sits on the roof and what comes out of the building.
Restaurants and roofs full of equipment
PVC. It has the strongest seams of the three and stands up to grease, oil and chemicals, which is why we put it on restaurants and on buildings with heavy HVAC equipment on the roof.
Standard commercial buildings and churches
TPO, for most of them. It’s the most common commercial membrane, the seams are heat-welded, and it’s the lower-priced of the two white membranes. The church at the top of this page in Sturgis, Michigan is a TPO replacement, and so is the Kendallville building above. More are in our project gallery.
A plain roof on a tight budget
EPDM can make sense when the price per foot decides it and there is little or no equipment on the roof. It has the longest track record of the three.
A house with a low-slope section
Shingles need some pitch to shed water, so a low-slope section of a house usually gets a membrane instead. On a home in South Bend we put Owens Corning Duration shingles (Onyx Black) on the main roof, a TPO membrane over the low-slope section, and new gutters. The whole job came to $21,007, and it’s listed with our other recent jobs on the pricing page. We also take small flat sections on their own: four recent TPO jobs, the largest 8 squares, came to between $3,465 and $8,664.
What moves the price on a flat roof
In short: The membrane sets the price per square foot. Tear-off, the deck, drainage, insulation code and rooftop penetrations move it from there.
On a 12,000 square foot building, the TPO range works out to $102,000 to $162,000 before anything below is added. These are the things that add to it:
- Existing layers to tear off: about $160 per square.
- A concrete deck instead of metal: $80 to $225 per square more, because of the fastening.
- Tapered insulation for a flat deck: about $150 per square over standard insulation.
- Michigan’s R-30 insulation instead of Indiana’s R-20: about $100 to $115 per square more.
- Skylights, HVAC units and vent pipes: each one needs flashing, so more of them means more detail work.
Size moves the schedule too. Some of our commercial projects take up to two months, and most go on in phases so the business stays open. For the full cost breakdown by system, see our commercial roofing cost guide for Indiana.
Tear-off or overlay?
An overlay puts a new membrane over the old one and saves the tear-off cost. It only works when the existing membrane is sound and there’s no trapped moisture underneath, and we check that with infrared scanning before we recommend one. If there’s hidden moisture, the old roof has to come off.
Keep the warranty in mind too. The 20-year warranty we can usually give on TPO and PVC comes with a full tear-off. If an overlay is on the table to save money, ask what warranty comes with each option before you decide.
Can a leaking flat roof be repaired?
Often, yes. A flat roof under about 15 years old with the problem in one place is usually a repair: a lifted seam, a loose flashing, a cracked pipe boot or a clogged drain. We walk the seams, flashings, penetrations and drains, take a core sample to check the insulation and deck underneath, and use infrared scanning when a leak is hiding.
Repair stops making sense in two situations. The first is age and cost: past 15 years, repairs start to become a band-aid, and once repair quotes pass 25% of the cost of a new roof, replacement is the better buy.
The second is a leak that keeps moving. We’ve seen owners pay to fix one area, then get a new leak on the far side of the building that has nothing to do with the first. That is the point to stop chasing leaks area by area. The repair money does more when it goes toward a complete section of new roof, at least a full slope.
Watch for standing water as well. If puddles are still on the roof two days after rain, that water is working on the seams, and fixing the drainage costs far less than a roof worn out early.
If water is coming in now, call (574) 370-8342. We get out fast, document the damage and stabilize the roof while you decide on repair or replacement. And if the membrane is aging but the deck and insulation are still sound, a spray-applied Conklin coating may buy more years; see roof coatings on our commercial roofing page.
Flat roof questions from building owners
How long does a flat roof replacement take?
In short: It depends on the size of the roof and how many layers come off. Some of our commercial projects take up to two months. Most go on in phases while the business stays open, and we coordinate access for deliveries and parking.
Is it worth patching a flat roof one leak at a time?
In short: Not when the leaks keep moving. If a repair in one area is followed by a new leak somewhere else, the money does more on a complete section of new roof, at least a full slope. If repair quotes pass 25% of the cost of a new roof, replacement is the better buy.
Do you put flat roofs on houses?
In short: We have. On a South Bend home we put a TPO membrane over the low-slope section and Owens Corning Duration shingles on the main roof, with new gutters, for $21,007. See the job on our pricing page →
What warranty comes with a TPO or PVC roof?
In short: On a full tear-off we can usually give a 20-year materials and labor warranty on TPO and PVC. Terms vary with the scope of the job, and we go over your exact warranty with you before any work begins. Read our warranties →
Commercial roofing by town
Better Way Roofing works on commercial buildings across Northern Indiana and Southern Michigan. For flat roof problems and how to spot them early, read our guide to commercial flat roof problems.
Book a flat roof assessment
If you’re considering work on a flat roof, the assessment is free.
We’ll walk the roof with you, check the seams, flashings and drains, and look for standing water. If the roof needs a closer look, the inspection that follows includes a core sample to see what’s under the membrane. If a repair will hold, we’ll say so.
If it needs more, you get an itemized, fixed-price proposal with the membrane, thickness and insulation spelled out. The number on the proposal is the number on the invoice.
Lyle Lehman, Founder