Membrane Blistering Repair

Blistering appears as raised, bubble-like areas in the membrane surface, caused by trapped moisture or air between roofing layers that expands under heat. This can happen from moisture trapped during original installation, or from water that’s found its way in through a separate failure point and is now trapped beneath the surface layer.

Not every blister is an active leak, but every blister is a weak point — the membrane over a blister is stretched and more vulnerable to punctures or further separation, and blisters tend to grow over time as more moisture gets trapped or as thermal cycling stresses the area further.

Repair generally involves cutting open the blistered area, allowing any trapped moisture to dry out (or removing wet insulation beneath if saturated), and patching the membrane back down properly bonded to the substrate. Left unaddressed, a blister will eventually crack open on its own, at which point it becomes an active leak rather than just a cosmetic issue.