Blistering is one of the most common and easily overlooked issues on flat roofs in Toronto. These raised bubbles or soft spots may seem harmless at first, but they’re often early warning signs of moisture problems and membrane failure. If not addressed promptly, blisters can rupture, leading to leaks, insulation damage, and costly repairs. A flat roof expert can help assess the severity and recommend the best repair strategy before things get worse.
Blisters form when air or moisture gets trapped between layers of the roofing membrane. In Toronto, where temperature swings between hot summers and freezing winters are frequent, that trapped moisture expands and contracts. This cycle causes the membrane to lift, creating visible bubbles. Over time, the expansion worsens, and the blister may burst—leaving the roof vulnerable to water penetration.
Another common cause of blistering is poor installation. If the membrane wasn’t properly bonded or was installed over a damp substrate, it creates the perfect conditions for blistering. Overexposure to UV rays also plays a role, especially on older roofs where the surface has started to degrade. The more sun the roof receives, the faster any trapped moisture expands.
While some small blisters may not leak immediately, they should never be ignored. Blisters weaken the roof’s overall structure and protective surface. Once they rupture—whether due to age, weather, or foot traffic—they expose the underlying layers to water, which can lead to a chain reaction of damage beneath the surface.
A professional flat roof expert will begin by inspecting the roof to determine the number, size, and location of blisters. In minor cases, blisters can be carefully cut out and patched using membrane-compatible materials.
Prevention is just as important as treatment. To avoid blistering, ensure your flat roof is inspected regularly, particularly after harsh winters or long periods of heat. Clearing debris, maintaining proper drainage, and reapplying protective coatings can go a long way in preserving the membrane.
If you’ve noticed soft, raised areas on your roof surface—or if you’re unsure whether bubbling is affecting your flat roof—now is the time to act. Delaying the repair increases the likelihood of rupture and the cost of restoring the roof later.
For professional evaluation and repair, contact Flat Roof Repair Toronto. Their experienced technicians offer full flat roof repair services and specialize in solving moisture issues through detailed residential flat roof repair that targets blistering before it leads to structural damage.
