Fiberglass shingles can develop blistering, which appears as small bubbles or raised areas on the surface of the shingles. This happens when moisture or air gets trapped under the shingle’s outer layer during manufacturing or after installation. Sometimes, blistering is caused by poor ventilation in the attic, allowing heat and moisture to build up, which damages the shingles over time. Another cause can be improper application of the shingles or using low-quality products. You can do simple checks yourself by inspecting your roof on a cool day—look for raised or cracked areas and see if they feel soft or brittle. Checking the attic for adequate ventilation and signs of moisture buildup is also a good starting point. While small blisters might not immediately impact your roof’s performance, they can lead to premature wear and leaks if left unattended.
If you notice blistering, it’s best to call a roofer for a thorough inspection to understand the full extent of the problem. An expert can assess whether the blistering is due to manufacturing defects, poor ventilation, or installation issues and recommend the right fix, which might involve replacing affected shingles or improving attic airflow. When talking to a contractor, ask whether the shingles are still covered under warranty and if the blistering is a known issue with that product line. Also, inquire about their plan to address attic ventilation because proper airflow can prevent similar problems in the future. Being proactive can help extend your roof’s life and avoid expensive repairs down the road.