Climb onto an RV roof on a hot Las Vegas afternoon and you may see soft bubbles or ripples in the membrane that weren't obvious that morning. Some are harmless and come and go with the weather. Others mean the membrane has lost its bond or been damaged by the wrong product. Knowing which is which saves you from cutting into a good roof, or from ignoring one that is starting to fail.
Why RV roof membranes bubble
Most RV roofs are a thin membrane, often EPDM rubber or TPO, glued to a wood deck. Dicor, a maker of RV roof membranes, lists its EPDM sheet at 0.035 inch thick and its TPO sheet at 0.025 inch. Material that thin moves with heat, humidity and the flex of the coach.
Dicor's roof FAQ gives several normal causes of air bubbles:
- Air that wasn't broomed out when the roof was installed
- Room left on purpose for the membrane to expand and contract
- Weather and humidity changes
- Flexing and twisting at deck seams during transit
- A big temperature difference between the inside and outside of the RV
Dicor says these bubbles will not blow up and pop, and that they come and go with conditions. It also says plainly: do not puncture them. A small slit lets water under the membrane, which is a much bigger problem than an air pocket.
Bubbles that are a warning sign
Not every raised spot is harmless. These are the ones worth a closer look:
- Membrane you can lift with a fingernail. RV repair guides describe ripples or bubbles you can lift by hand as adhesive failure between the sheet and the deck. A small area can be re-bonded; a whole loose sheet is a bigger job.
- Swelling or uneven thickness. Dicor warns that petroleum distillates cause an EPDM membrane to swell or balloon. That damage often comes from cleaners, conditioners or protectants that were never meant for the roof.
- Soft or spongy deck under the bubble. That points to water in the decking, not air in the membrane.
- Bubbles near seams, vents or edges with interior stains. Water may be getting in at a penetration and spreading under the sheet.
- Widespread bubbling or lifting. Repair guides agree this is the point to stop patching and get a professional inspection.
How to check bubbles safely
Only go on the roof if your RV is rated to walk on and you can do it safely. A wet membrane can be very slippery.
- Look at the same spots at different times of day. Bubbles that shrink in the cool morning and grow in the afternoon sun are usually expansion.
- Press gently around the bubble, not on it. Feel for a soft or spongy deck.
- Check the nearest seams and penetrations. Look for cracked or separated sealant at vents, the A/C, antennas and edges.
- Look inside under the same spot. Ceiling stains, soft panels or a musty smell point to water, not air.
- Check what has been used on the roof. Dicor says to avoid cleaners or conditioners with petroleum distillates, harsh abrasives or citrus-based formulas.
- Take photos. Note the location, size and time of day so a shop can compare.
What not to do
- Don't cut, puncture or "vent" a bubble.
- Don't glue or seal over a raised, wet or dirty area. Repair guides warn that an incorrect fix can trap water or make the problem worse.
- Don't assume a "rubber roof" product is safe on TPO or PVC. Use only products approved for your membrane.
- Don't stack new coatings on a membrane that is loose from the deck.
Quick guide: what the bubble may mean
| What you see | Likely meaning | Next step |
|---|---|---|
| Soft bubbles that change with temperature, deck firm | Normal expansion (per Dicor) | Leave it alone and keep up routine checks |
| Membrane lifts by hand, ripples spreading | Adhesive failure | Shop inspection before any coating |
| Swollen, uneven, ballooned areas | Possible chemical damage | Stop using that product; get it inspected |
| Bubble over a soft deck or near a stain | Water under the membrane | Inspection soon to find the entry point |
How a shop approach helps
At Sky Sealed, every roof starts with an assessment of membrane health, seams, decking and penetrations, followed by a written quote. Sound membranes typically receive a multi-layer silicone system with embedded fabric at seams, vents and penetrations. Severely damaged membranes may need replacement instead. Qualifying full systems come with a 20-year workmanship warranty, with the terms in writing before pickup.
For more on what we check, see what a shop RV roof inspection includes. If you are comparing products, read lap sealant vs silicone for RV roofs. Shopping for a used coach? Use our used RV roof checklist.
Frequently asked questions
Are bubbles in an RV rubber roof normal?
Often, yes. Dicor says air bubbles can come from installation, weather, humidity, transit flexing or inside-outside temperature differences, and that they come and go with conditions without hurting roof performance.
Should I pop a bubble in my RV roof?
No. Dicor specifically asks owners not to puncture air bubbles. A cut lets water under the membrane and into the deck.
What causes an RV roof to swell or balloon?
Dicor warns that petroleum distillates cause EPDM to swell or balloon. Check the labels on any cleaner, conditioner or protectant you have used on the roof.
When are RV roof bubbles a problem?
When the membrane lifts by hand, the deck feels soft, there are interior stains, or the bubbling is widespread. Those signs call for an inspection rather than a patch.
Book a shop inspection
Not sure whether your roof bubbles are normal? Bring your RV to Sky Sealed at 4416 Alderbaren Ave, Las Vegas, NV 89103, along with photos of the bubbles and any interior marks. Call (702) 296-7300, email curtis@cbtbllc.com, or use the quote form.
Book a shop inspection and get a written quote for a roof system that fits your membrane's real condition.