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Raleigh Commercial Roofs

Serving Raleigh and nearby areas

Roof Blisters and Open Seams in Raleigh, NC

Bubbles in the membrane and seams that lift are early signs of trapped moisture or lost bond, so call (984) 464-8602 for a free inspection that tells you which ones need work and what it costs.

Call now: (984) 464-8602 or book your free inspection online

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A few quick answers. A local roofing specialist calls you back the same business day.

Local to Raleigh

We connect property owners in Raleigh and nearby areas, including Research Triangle Park, Durham, Cary, Morrisville, Apex and Holly Springs, with one independent local commercial roofing specialist.

  • Hot roofs swell blisters

    Normal July highs at Raleigh-Durham are near 91 degrees. Federal cool roof guidance shows dark roofs run far hotter than the air, and that heat makes trapped vapor expand.

  • Small blisters can be watched

    Facility management guidance says small blisters can usually be left alone and monitored, while larger or growing ones point to moisture under the membrane.

What it costs

Typical published ranges for Raleigh. The contractor's written estimate is the price, and the inspection is free.

WorkTypical range
Blister repair $250 to $1,500per repair
Seam repair $200 to $1,000per repair
Membrane patch $250 to $1,750per repair
Infrared moisture scan $0.05 to $0.12per sq ft

See typical commercial roofing prices in Raleigh

What you will notice

Blisters and seam problems are often found during a routine walk on the roof or by an HVAC tech. Here is what they look like:

Raised bubbles

In the membrane, from the size of a coin to several feet across.

A soft, spongy spot

That gives when you step on it.

Bubbles that are bigger in the afternoon

Than in the morning.

A blister with a crack

Or split across the top.

A seam edge you can lift

With a fingernail or a putty knife.

A dark line or gap

Along a seam on a white TPO roof.

Wrinkles or fishmouths

Small open tunnels where two sheets overlap.

Seam tape peeling

At the ends on an EPDM roof.

What causes blisters

A blister is a spot where the membrane has come loose from what is under it, and the gap has filled with air or water vapor. Industry and government research points to a few common causes:

Moisture trapped during install

Insulation or a deck that was damp when the roof went on, or materials that got wet before they were used.

Moisture from a leak

Water gets in somewhere else, spreads under the membrane and turns to vapor in the heat.

Poor bond

On fully adhered roofs, a missed spot of adhesive leaves a void. On older built-up and modified bitumen roofs, gaps between layers do the same.

Sun heat is what makes them grow. When the roof heats up, the trapped vapor expands faster than it can escape. When it cools, the blister shrinks a little. That daily push works the edges of the blister loose.

What causes open seams

A single-ply roof is made of large sheets joined at the seams. TPO seams are welded with hot air. EPDM seams are glued or taped. Seams fail for a few reasons:

A weak weld or bond at install

Voids or cold welds that looked fine at first.

Daily heat movement

The roof grows in the sun and shrinks at night, which pulls at every seam.

Age

Adhesives and tapes on older EPDM roofs dry out and let go.

Wind

Gusts lift the membrane and flex seams near edges and corners.

Foot traffic

Techs walking the same path to rooftop units stress the seams they cross.

Why it shows up in Raleigh

Raleigh summers are long and hot. Normal July highs at Raleigh-Durham sit near 91 degrees, and a dark roof in full sun gets much hotter than the air. ENERGY STAR notes a white roof can run about 50 degrees cooler than a grey one on a summer afternoon, which shows how hot darker roofs get.

Humidity matters too. Raleigh averages about 46 inches of rain a year. A roof that takes on even a little water stays damp in humid weather, and that moisture feeds blisters.

Cosmetic or urgent

Watch it: a few small blisters that are not growing, have no cracks, and show no wet insulation under them. Mark them and photograph them twice a year.

Repair soon:

  • Blisters that are large, growing, or close together
  • Any blister with a crack or split
  • Seams you can lift or see into
  • Seam problems near drains or low spots where water sits

Call now: an open seam or cracked blister with a leak below. Water is going straight into the insulation every time it rains.

What the fix usually is

For blisters, the roofer checks for wet insulation first, often with an infrared scan or a small core. A dry blister that has opened is cut out, the area is dried and cleaned, and a patch of matching membrane goes over it. If the insulation is wet, that section is cut out and replaced before patching.

For seams, a TPO seam is cleaned and welded again with a hot air welder, or covered with a welded strip. An EPDM seam is cleaned, primed and covered with new seam tape.

For widespread problems, spot repairs stop making sense. If blisters and open seams are all over the roof, ask about a full moisture scan. A roof that is still mostly dry may be a candidate for a coating. A roof with a lot of wet insulation usually needs to be replaced.

Before the inspection

  • Photograph each blister and seam problem with a coin or tape measure for size
  • Note where they are on a simple roof sketch
  • Check if blisters change size from morning to afternoon
  • Do not cut, pop or tape anything yourself
  • Find your warranty, since some require repairs by an approved contractor

About these prices

The cost table shows typical repair ranges from Fixr's published flat roof repair guide and a commercial inspection cost guide. They are not quotes.

Call (984) 464-8602 or send the form with the address. A local commercial roofer is set up the same day you call.

Frequently asked questions

Should I pop a blister on my flat roof?

No. Cutting a blister without a plan lets water straight into the roof. A roofer cuts out a blister only when it will be patched the same day, and checks for wet insulation under it first.

Are roof blisters a big deal?

Small blisters that are not growing can often be left alone and watched. Large or growing blisters, or ones that have cracked open, usually mean moisture under the membrane and should be repaired.

Why do blisters show up in summer?

Heat makes trapped air and water vapor expand. On a hot Raleigh afternoon the roof gets far hotter than the air, so a small pocket can swell into a blister you can see.

Can an open seam be fixed or does the roof need replacing?

Most open seams can be repaired. TPO seams are cleaned and welded again or covered with a strip. EPDM seams are cleaned, primed and covered with seam tape. If seams are failing all over the roof, it may be time to price a coating or a new roof.

How much does blister or seam repair cost?

Published national guides put blister repair at about $250 to $1,500 and seam repair at about $200 to $1,000. Wet insulation under the area adds to the cost.

Other services

Common commercial roofing problems in Raleigh

Areas we serve around Raleigh

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