Blisters on a roof surface are a common issue that can compromise the integrity of your roofing system if not addressed. These raised areas, which resemble bubbles, occur when air or moisture becomes trapped beneath the roofing material. Understanding what causes blisters, the risks they pose, and how to fix them is crucial for maintaining a durable and effective roof.

Roof blisters are raised areas that form on the surface of roofing materials, such as shingles or membranes. They are often filled with air, moisture, or both and may appear as small bubbles or large protrusions. Blisters typically occur on flat or low-slope roofs but can also affect shingle roofs.

1. Trapped Moisture

During installation, moisture can become trapped between layers of the roofing system. When exposed to heat, this moisture expands, creating a blister.

2. Heat and Temperature Fluctuations

Intense sunlight and heat can cause roofing materials to expand and contract, stressing the layers and leading to blisters over time.

3. Improper Installation

If the roofing materials are not installed correctly, such as by failing to properly adhere layers or allowing contaminants like dust to interfere, blisters are more likely to form.

4. Aging Materials

Older roofs are more prone to blisters as the materials degrade, lose flexibility, and become less resistant to environmental stressors.

5. Poor Ventilation

Inadequate attic or roof ventilation can trap heat and moisture, increasing the likelihood of blister formation.

6. Defective Materials

Low-quality or damaged roofing materials are more susceptible to blistering.

1. Compromised Waterproofing

Although small, blisters can weaken the roof’s waterproofing properties, increasing the risk of leaks.

2. Popped Blisters

If blisters burst due to foot traffic, hail, or other impacts, they expose the underlying layers to moisture and UV damage, accelerating roof deterioration.

3. Shortened Roof Lifespan

Left unaddressed, widespread blistering can reduce the longevity of the roofing system and necessitate early replacement.

4. Energy Inefficiency

Blisters disrupt the smooth surface of the roof, which may reduce its energy efficiency, particularly on reflective or insulated roofs.

1. Inspect the Roof

• Visual Inspection: Look for raised areas or bubbling, especially during warmer weather when blisters are more noticeable.

• Professional Assessment: A roofing contractor can determine whether the blisters are superficial or indicate deeper issues.

2. Temporary Solutions

• Avoid walking on blistered areas to prevent them from popping and causing further damage.

• Cover popped blisters temporarily with roofing tape or a sealant to prevent moisture intrusion.

3. Repairs

• Minor Blisters: For non-popped, superficial blisters, professional resealing may suffice.

• Popped Blisters: Remove the damaged material, repair the exposed area, and replace the roofing layer to restore the waterproofing.

4. Replacement

• If blisters are extensive and widespread, a roof replacement may be necessary to ensure long-term protection and performance.

1. Ensure Proper Installation

• Hire a reputable contractor who follows manufacturer guidelines for installation and ensures materials are clean, dry, and properly adhered.

2. Improve Ventilation

• Install adequate attic or roof ventilation to minimize trapped heat and moisture.

3. Use High-Quality Materials

• Opt for durable roofing materials with proven resistance to blistering and other common issues.

4. Regular Maintenance

• Schedule regular roof inspections and address small issues before they escalate into significant problems.

5. Avoid Foot Traffic

• Minimize walking on the roof, especially on hot days when blisters are more susceptible to popping.

Blisters can be tricky to evaluate, as some may not pose immediate risks while others signal underlying problems. If you notice blisters or other roof issues, it’s best to consult a roofing professional to assess the damage and recommend appropriate solutions.

Roof blisters may seem minor, but they can signal deeper issues with your roofing system. By addressing blisters promptly and taking preventive measures, you can extend the life of your roof and avoid costly repairs. Regular maintenance and professional inspections are key to keeping your roof in top condition.