If you have noticed raised bumps or small craters on your shingles, you may be looking at roof blistering. It is one of the most common roofing problems homeowners encounter in the summer and one of the most misunderstood. Many assume it is cosmetic. It is not.
What Roof Blistering Is
Blistering happens when moisture or volatile gases become trapped inside an asphalt shingle during manufacturing or installation. When temperatures rise, those trapped elements expand and push outward, forming a bubble beneath the surface of the shingle. Summers in Joplin, MO are no exception; August heat in the Four-States area creates exactly the conditions that accelerate this process.
What It Looks Like
Blisters appear as raised, rounded bumps on the face of a shingle. They can range from the size of a pencil eraser to several inches across. When they pop from heat cycles or foot traffic, they leave behind a shallow crater with exposed or missing granules at the center. The edges of a popped blister tend to be soft and gradual.
What Causes It
Poor attic ventilation is the most common culprit. When heat has nowhere to escape, it builds up beneath the roof deck and drives temperatures inside the shingles to extreme levels. In Pittsburg, KS and across the region, attic temperatures can exceed 150 degrees in August, well beyond what shingles are designed to absorb day after day. Blistering can also result from manufacturing defects or from improper installation where shingles were nailed too tightly or applied over existing layers without proper preparation.
Understanding the cause matters. Replacing blistered shingles without fixing the ventilation problem underneath means the new shingles will blister too. A proper repair addresses both the symptom and the source.
Why It Is a Problem
Blistering is not just a cosmetic issue. The granules on asphalt shingles serve a real purpose. They protect the shingle mat from UV damage and weathering. When blisters pop and granules are lost, that protection disappears. Over time, the exposed mat becomes brittle, cracks, and allows moisture to reach the roof deck beneath.
A roof with widespread blistering ages significantly faster than it should. What might have been a roof with ten good years left can lose that lifespan quickly if blistering goes unaddressed.
What to Do If You Suspect Blistering
Start with what you can safely see from the ground. Look for raised bumps or shallow circular craters on the shingle surface. Note whether the damage appears scattered randomly across the roof rather than concentrated in one area. Take photos and document where it appears most.
Do not attempt to walk the roof yourself. Blistered shingles are fragile, and foot traffic can pop blisters that have not yet opened, accelerating the damage.
The right next step is a professional roof inspection. A qualified roofer can assess how widespread the blistering is, identify whether ventilation is the underlying cause, and recommend whether spot repairs or broader shingle replacement is the right course of action.
Let Bridgewater Roofing Take a Look
The Bridgewater Roofing team serves homeowners across Missouri and the Four-States area. If you are seeing signs of blistering on your roof this summer, do not wait for the damage to deepen.
Contact Bridgewater Roofing today for a professional roof inspection and an honest assessment of what your roof needs.