The membrane with welded seams
TPO is the most-installed commercial roofing membrane in the country, and there’s a reason for it: heat-welded seams. Where old modified-bitumen roofs rely on adhesives and torch work, a TPO roof’s seams are literally welded into a single sheet of plastic. Done right, the seam is stronger than the membrane around it. Done wrong, whether too fast, wrong temperature, or dirty membrane, it’s a leak with a warranty dispute attached. The system is only as good as the crew running the welder.
That’s the whole TPO story in one paragraph. Everything else about the system, the reflectivity, the install speed, the price, is real, but the seams are why it took over the market and the seams are where cheap installs die.
What TPO does well
- Reflects heat. White TPO bounces summer sun instead of soaking it. On a big single-story footprint with rooftop units, the cooling savings are real money every August. Walk any warehouse block in Chicagoland or Carol Stream and you’ll see why white roofs took over the industrial parks.
- Handles Chicago winters. Modern TPO formulations stay flexible in cold and take freeze-thaw cycling well. The membrane doesn’t care about snow. What matters is the insulation and drainage design underneath it, which is where we spend most of our design time.
- Big roofs, fast. Wide sheets and mechanical attachment make TPO the most efficient system to install on large, open warehouse decks. Less labor time on your roof, fewer weather windows to gamble on. On the I-55 distribution corridor through Bolingbrook, that speed is the difference between one season and two.
60 mil or 80 mil
TPO comes in several thicknesses. The common commercial choices are 60 mil and 80 mil. The number that matters more than total thickness is the thickness over scrim: the amount of weatherable membrane sitting above the reinforcement fabric. That’s the material the sun, the hail, and the maintenance guy’s boots actually wear through.
Here’s our standing advice: on a roof you plan to keep for the long haul, the upgrade from 60 to 80 mil is the cheapest durability you can buy on the entire project. The labor is identical. The insulation is identical. You’re paying only for more membrane, and membrane is not where the money in a roof lives. We’ll price both on every scope so you can see the difference for yourself.
Where TPO is the wrong answer
We’ll tell you when it isn’t the right system, because we also install EPDM and modified bitumen. Roofs with dozens of penetrations and odd geometry often come out better in EPDM or mod-bit, where detail work is faster and more forgiving. And restaurant exhaust and oily manufacturing environments eat TPO membrane; if that’s your building, we’ll say so up front, even when the honest answer is a system we don’t install. That’s the point of the assessment: the building picks the system, not the sales sheet.
How we build a TPO roof
Tear-off or recover gets decided by what the core samples say, not by what’s cheaper to sell. Wet insulation comes out, because burying it under new membrane is how you buy the same leak twice. Then the assembly goes together in order:
- Insulation to current code R-value. Chicagoland sits in climate zone 5, and when a roof comes off down to the deck, the energy code requires the insulation to come up to today’s standard. That’s usually the biggest single change from what was up there before.
- Cover board where the roof takes traffic. Around rooftop units and along service paths, a hard cover board is what keeps a dropped tool or a careless boot from becoming a puncture.
- Membrane, mechanically attached or fully adhered depending on the deck, the wind zone, and the building’s use. Mechanically attached is faster and cheaper on big open decks. Fully adhered lies flatter, handles wind uplift at edges and corners well, and is the quieter choice under wind.
- Every seam heat-welded and probed. Welds get tested with a seam probe, not eyeballed from ten feet.
- Every curb and penetration flashed in manufacturer-spec detail. Flashings are where roofs leak. They get the slow, careful work.
We install Carlisle, GAF, and GenFlex TPO systems, spec’d for manufacturer system warranties. That’s the warranty covering membrane AND workmanship, the one that’s still worth something in year 15.
What a TPO roof costs
We don’t publish per-square-foot numbers, because they’d be fiction. The honest cost of your TPO roof lives in the details: tear-off or recover, how much insulation code requires you to add, deck condition, edge metal, and how many units and penetrations we’re flashing. What we can tell you: TPO is generally the most cost-efficient single-ply for big open roofs, membrane thickness is the cheapest durability upgrade on the project, and an itemized scope, the thing we email you free after a roof assessment, is how you find out the real number without a salesman in your office.
How the estimate works
No sales calls, no pressure, no guy in a polo following up every day. You fill out the form. An estimator walks your roof within 48 hours: measures it, photographs it, cores it if the insulation is suspect. You get an itemized scope by email covering system options, insulation plan, schedule, and warranty terms. Share it with your ownership group or facilities team and decide on your own time.
Free TPO Roof Estimate
On-site roof assessment within 48 hours. Itemized scope by email.
Licensed • Insured • 20+ Years of Commercial Roofing
Frequently Asked Questions
How long does a TPO roof last in Chicago?
A properly installed 60-mil TPO system realistically gives you 20 years here; 80-mil stretches that. The roofs that die at year 12 die from installation shortcuts and skipped maintenance, not from the membrane. Freeze-thaw finds bad welds and lazy flashing details first, which is why seam probing and manufacturer-spec flashings matter more than the brand on the roll.
TPO or EPDM, which should I pick?
Big open roof, cooling costs, want the seams welded: TPO. Lots of penetrations, smaller roof, want the longest track record in freeze-thaw: EPDM makes its case. The honest answer depends on your deck, your rooftop equipment, and how the building is used, which is exactly what the free assessment settles in writing.
Can you install TPO over my existing roof?
Sometimes. If there's only one existing layer and the core samples come back dry, a recover saves real money. It's a disaster when it's used to hide wet insulation. Code caps every roof at two layers, so if you already have two up there, the next roof is a tear-off by law. The cores decide, not the sales pitch.
Get a Free TPO Roof Installation for Chicagoland Commercial Buildings Estimate
Every estimate is free, on-site, and itemized. Most site walks within 48 business hours.