TPO Roof Repair: Common Problems and How to Fix Them

Mose Borntreger • June 23, 2026

Seam, flashing, puncture, and ponding repairs for commercial TPO roofs in Wisconsin & Minnesota.

TPO is one of the most common single-ply membranes on commercial flat roofs in Wisconsin and Minnesota — and when it starts to fail, it almost always fails in the same handful of places. We repair commercial TPO roofs across western Wisconsin and central Minnesota: warehouses, manufacturing plants, retail centers, clinics, restaurants and ag buildings.

Most TPO problems are fixable if you catch them before water gets into the insulation and deck below. Seams open up, something punctures the membrane, flashing lets go at a curb. Caught early, those are repairs — not a re-roof. Caught late, they turn into wet insulation and a much bigger number.

This guide covers the TPO failures we see most often on commercial roofs, how each one is properly repaired, and how to tell when a roof has enough life left to repair versus when it’s time to restore the whole system. If you’re responsible for a white, heat-welded membrane roof on a commercial building, this applies to you. The inspection is free and we’ll tell you straight which one you’re looking at.

The most common TPO repair problems

1. Seam separation

TPO sheets are heat-welded together, and the seam is only as good as the weld. Age, foot traffic and thermal movement pull them apart over time. A separated seam is a direct path to the deck, and it usually shows up as a leak nowhere near the actual opening.

How it’s fixed: we clean the area and re-weld it with a hot-air welder. Where the seam is too far gone to re-weld cleanly, we cover it with TPO strip material welded over the top. A bead of sealant alone is not a seam repair.

2. Punctures and tears

Dropped tools, hail, a service tech walking a route nobody armored. Punctures are the most common repair we see on roofs that are otherwise in good shape, and a puncture the size of a pen tip is enough to soak the insulation under it over a season.

How it’s fixed: we weld a TPO patch over the damage, extending well past the edges of it. If the puncture is somewhere that gets regular foot traffic — a path to a rooftop unit, say — walk pads are worth adding so you’re not patching the same spot next year.

3. Membrane shrinkage at the edges and curbs

TPO pulls as it ages. You’ll see it first at the perimeter and around curbs, where the membrane starts lifting away from the flashing and putting tension on every detail it’s attached to.

How it’s fixed: isolated spots get re-secured and re-flashed with new TPO. But widespread shrinkage is a different conversation — that’s a roof telling you it’s near the end, and patching it just moves the failure to the next weak point. More on that below.

4. Flashing, scuppers, and penetration failures

Anything that comes through the roof is a place the roof can fail. Curbs, drains, scuppers, pipe boots, the base of every rooftop unit. These details take the most thermal stress and are the second most common leak source after seams.

A good example: on a large school-district roof in the Burnsville, MN area, the open field of the membrane was holding up fine — but the wear showed up exactly where it always does, at the scuppers, the parapet flashing, and the curbs around the rooftop HVAC units. The flashing around several of those curbs had started to fail, and a couple of the low spots near the drains were soft underfoot — a sign of wet insulation working in below the membrane. We stripped and rebuilt the failing curb and scupper flashing, cut out and replaced the wet insulation before it could spread to the deck, re-welded the details, and cleared the drains so water moved off instead of pooling.

How it’s fixed: we strip the detail back and rebuild it with new TPO. If the roof has been leaking in that area, what’s underneath gets looked at before the detail goes back together — rebuilding over saturated insulation just hides the problem for a season.

5. Ponding water breaking down the membrane

Standing water doesn’t automatically mean a leak, but it does mean the membrane and the seams under it are working harder than they should be, and it accelerates everything else on this list. It usually points to a clogged drain or a low spot, not the membrane itself.

How it’s fixed: drainage gets corrected first. Repairing seams under a pond without fixing why the pond is there is how a roof ends up repaired three times. If the leak itself is the mystery, start with finding the real source of a commercial roof leak — water rarely shows up where it gets in.

How we know the weld will hold

A TPO seam is a weld, not a glue joint — and a weld is only as good as the settings behind it. Welder temperature, travel speed, the age and condition of the membrane, what the weather is doing that day. All of it changes the result.

So before we weld your seams, we weld a test sample and pull it apart.

How it tears is the test. A clean weld doesn’t come apart at the seam — the material itself gives out before the weld does. If the sample tears wrong, the settings get adjusted and we run another one. Nothing permanent happens to your roof until the test says the weld is right.

We do this every time we weld, not once at the start of the job. Conditions change through a day on a roof, and a seam welded at the wrong setting looks exactly like a seam welded at the right one until it fails two winters from now.

Signs your TPO roof needs repair now

A leak that shows up in the same spot after it’s already been repaired

Staining or bubbling on the ceiling tile below a rooftop unit

Visible seams that have lifted, curled or opened

Membrane pulling away from curbs, walls or the perimeter edge

Water still standing on the roof more than a couple of days after rain

Ice building up at drains and low spots through the winter

On that last one: ice damming gets talked about like it’s a steep-roof residential problem. On flat and low-slope commercial roofs it’s a bigger issue than most owners expect. Water backs up behind ice at drains and low spots, sits on seams it was never meant to sit on, and finds the weakest weld. If you’re seeing ice build up in the same places every winter, that’s worth a look before spring.

TPO repair vs. restoration: when a patch isn’t enough

We’d rather tell you a repair won’t hold than sell you one that won’t.

Repair makes sense when the problems are isolated — a handful of seams, a few punctures, one bad curb — and the rest of the membrane and the insulation under it are sound. That is standard commercial roof repair work.

Repair stops making sense when the failures are everywhere at once. Widespread shrinkage, seams letting go across the whole field, saturated insulation over a large area. At that point every patch buys you a season and you’re paying for the same roof twice.

When a roof is past patching but the structure underneath is still good, the next conversation is usually a recover or a single-ply restoration system rather than a full tear-off. That’s a different scope and we’ll walk you through it honestly. Coating season here runs from about early May to mid-October, weather at both ends — so if you’re reading this in the fall, it’s worth getting on next season’s schedule now instead of waiting for the spring rush.

Wet insulation — how we actually handle it

This is where a lot of roofing conversations get slippery, so here’s ours straight.

We don’t scan for moisture. No instruments, no infrared. We look.

If a roof has been leaking, we inspect the insulation and check it for damage before any new membrane goes over the existing roof. What’s underneath is what decides whether a recover makes sense. Laying a new membrane over saturated insulation doesn’t solve anything — it seals the problem in and you pay for the roof twice.

Where the leak shows up tells us something before we ever get on the roof. A leak at the edge of a wall usually means the water damage is fairly contained. A leak in the middle of a room more often means there’s moisture sitting in the insulation. That’s a judgment call based on what the roof is doing, and we’ll tell you it’s a judgment call rather than dress it up as something more precise.

We don’t turn work down because a roof has wet insulation. Some contractors use it as a reason to walk away, or as a lever to sell a full tear-off that wasn’t necessary. We’d rather be straight with you about when a roof can be recovered and when it can’t, and let you make the call with real information.

Where we work

From our Clear Lake, Wisconsin shop: Hudson, New Richmond, Menomonie, River Falls and Eau Claire, plus the surrounding western Wisconsin communities.

From our Motley, Minnesota shop: the Brainerd Lakes area — Brainerd, Baxter, Little Falls and the towns around them.

Flat and low-slope commercial roofs only. We don’t do residential.

Why American Eagle Roofing & Coatings

Commercial flat and low-slope is what we do. Not a residential company taking commercial work on the side.

Two shops, two states. Clear Lake, WI and Motley, MN — we’re not driving four hours to look at your roof.

Licensed and insured.

Every weld gets tested before it goes on your roof. Test sample, pulled apart, read, adjusted if it’s not right. Every time.

We weld TPO properly. Seams get re-welded or stripped over with TPO material. Caulk smeared into a failing seam buys a few months and costs you the repair twice.

We tell you when a repair won’t hold. A patch that fails in six months is worse for you than an honest conversation today.

Free inspection. No charge to have us come look and tell you what you’ve got.

Frequently asked questions

Can a TPO roof actually be repaired, or does it have to be replaced?

Most of the time it can be repaired. TPO is a weldable membrane, which means new material can be fused to the existing roof rather than just stuck to it. Isolated seams, punctures and failed details are all normal repairs. Replacement becomes the answer when the failures are widespread or the insulation underneath is saturated over a large area.

How do you fix a TPO seam?

The area is cleaned and re-welded with a hot-air welder. If the original seam is too degraded to re-weld cleanly, we weld TPO strip material over the top of it instead.

How do you know the weld is any good?

We weld a test sample and pull it apart before we weld your seams. A clean weld tears through the material rather than separating at the seam. If the sample comes apart wrong, we adjust and run another one. That happens every time we weld, not once at the start of a job.

My roof has been repaired before and it’s still leaking. Why?

Usually one of three reasons. The leak is entering somewhere other than where it’s showing up inside, so the repair went to the wrong spot. Or the underlying cause — ponding, a drainage problem, a failing detail — was never corrected, so the repair was always going to fail. Or the original fix was sealant over a seam that needed to be welded.

Should I coat the roof instead of repairing it?

Depends on how much of the roof is failing. A coating goes over a roof that’s fundamentally sound and gives you a continuous new surface — it doesn’t fix a roof that’s coming apart underneath. If the problems are isolated, repair them. If they’re everywhere and the deck and insulation are still good, a restoration coating is worth pricing.

How do I know if I even have TPO?

TPO is usually the white membrane, but not always, and PVC looks similar. The TPO vs. EPDM vs. PVC comparison walks through how to tell them apart.

Do you check for wet insulation?

If the roof has been leaking, yes — the insulation gets inspected and checked for damage before any new membrane goes over the existing roof. We don’t use moisture scanners. We look, and we read the likely extent from where the leak is showing up.