Florida Certified Roofing Contractor CCC 1334537
What does it mean when my flat roof membrane has blisters or bubbles?
A straight answer from a Florida certified roofing contractor — then what you can check yourself and when to call. Free quote: (954) 775-8990.
A blister is a pocket of trapped air, moisture or vapor between layers of the membrane, or between the membrane and the insulation or deck below it. It means the layers have lost their bond in that spot. It does not automatically mean the roof is leaking.
What matters is the condition of each blister. A small, intact, dry blister away from seams and drains can often be watched. A blister that has split, sits on a seam or flashing, feels soft underfoot from below, or appears with ceiling stains needs repair, because water can get in and soak the insulation.
Why flat roof blisters form
Most blisters start during installation or soon after. If the deck, insulation or base layers were damp when the membrane went over them, that moisture is sealed in. Florida's humidity and near-daily summer storms make a truly dry surface harder to get, and morning dew can be enough. Poor adhesion in one area has the same result, leaving a pocket for air to collect.
Heat then does the rest. On a hot afternoon, trapped air and moisture vapor expand and push the membrane upward. Over many heat cycles the pocket grows, and UV exposure makes the surface more brittle and more likely to crack at the blister's edge.
Blisters can also point to a problem underneath. Wet insulation, a slow leak from an earlier flashing failure, or ponding water that keeps the area saturated can all feed them. This is why a blister is a reason to look closer, not just to patch the bump.
What you can check yourself (from the ground, attic and ceiling)
Look from the ground or an upper window
Note where raised spots are, whether they cluster near drains, seams or walls, and whether any look cracked or shiny where the surface has worn off. Photos help a lot.
Check ceilings below the blistered area
Yellow or brown stains, peeling paint or a musty smell suggest water may already be getting in.
Look at the underside of the deck
If you have attic or crawl access to a low-slope section, look for damp, darkened or stained decking and wet insulation under the blisters.
Watch the roof after a rain
From the ground, note whether water stays on the roof long after the rain stops. Standing water speeds up membrane wear and can be a cause of the damage.
Leave the blisters alone
Do not walk on the roof, press on blisters or cut them open. Opening one lets water in and can make a small problem larger.
When to call a pro
Call when blisters are split or leaking, when they are spreading or sit on seams, flashings or around drains, or when you see ceiling stains or damp insulation. Several blisters in one area often mean the layers underneath are wet, which a surface patch won't fix. Many roofers cannot tell what is under a blister without opening it, so an inspection is the way to know.
Roofing work in Florida legally requires a licensed roofing contractor and generally a permit from the local building department; a contractor's license is verified on the Florida DBPR website. If you live in a condo or an HOA, you may also need association approval before work starts. We can quote the repair in writing, and you can reach us at (954) 775-8990.
What a pro will do
- Find out how far the moisture goesWe inspect the blistered areas and the surrounding membrane, seams and flashings to see whether the insulation and deck underneath are wet.
- Cut out and repair the affected areaWet insulation is removed and the membrane is rebuilt with a repair suited to the existing system, such as modified bitumen, built-up roofing or a self-adhered system. Rotten plywood and fascia replacement is included in our scope.
- Correct what feeds the problemIf ponding is a factor, tapered insulation and crickets can improve drainage, and new drains or scuppers can be added. Failed base flashing at parapets and curbs is rebuilt.
- Replace the system when repair isn't enoughIf moisture is widespread, tear-off and deck replacement may be the sounder answer. Code limits on how many roof layers may remain can also affect that decision.
- Put it all in writingYou get a free estimate and a written flat-rate quote that says what is included. We pull permits under our own license, schedule and pass inspections, close out the permit and clean up fully.
Related questions
- Will a flat roof blister go away on its own?
- Usually not. A blister may flatten a little when it cools, but the lost bond underneath stays, and heat cycles tend to make it larger over time.
- Should I pop a blister to let the air out?
- No. Cutting it open can let water into the insulation and leave a hole in the membrane. Leave the repair to a roofer who can dry and rebuild the area properly.
- Can blisters just be coated over?
- A coating over an intact blister doesn't restore the bond underneath, and if the layers below are wet the moisture stays trapped. Whether a repair or coating makes sense depends on what an inspection finds.
- Why do blisters seem worse after summer?
- Heat expands the trapped air and vapor, and the summer wet season adds moisture to the roof. Blisters that were small can become noticeable or crack open during that stretch.
- What decides the price of a blister repair?
- The main factors are how many blisters there are, how far the wet insulation or deck extends, the roof's access and material, and what is found once the area is opened. We give a free estimate and a written flat-rate quote.
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