Your roof is built to protect your home, with roof shingles serving as the primary layer protecting your home from weather. In a place like Eagan, Minnesota, harsh weather, heat exposure, and storm damage can quietly wear it down. One of the most common, yet least understood forms of damage is roof blistering. These small bumps on asphalt shingles may seem harmless, but over time, they can compromise your roof’s integrity.
At Krech Exteriors, we’ve served Eagan homeowners for over 35 years. We know the local climate, the most common roofing issues, and how to fix them before they become major problems. Here’s what you need to know about roof blistering in Eagan—and how to stop it from damaging your home.
Key Takeaways
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Roof blistering is common in Eagan due to hot summers and cold winters.
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Blisters form from trapped moisture or heat, often made worse by poor attic ventilation.
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If left untreated, blisters can lead to granule loss and water damage.
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Quality shingles and proper ventilation help prevent blistering.
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Krech Exteriors offers professional roof inspections and repairs for homes across Eagan.
What Is Roof Blistering?
Roof blistering refers to small, raised bubbles (often described as a bubble like blister) that form on the surface of asphalt shingles. These are known as asphalt shingle blisters, a specific type of blistering that affects roofing materials. In Eagan, these blisters typically appear during summer, when intense sun exposure causes trapped moisture or air to expand beneath the shingle surface.
Local Insight: South-facing roofs in Eagan neighborhoods like Diffley Commons or Stonehaven tend to blister faster due to direct sun exposure throughout the day.
What Causes Roof Blistering in Eagan Homes?
Trapped Moisture
Shingles can develop blisters if moisture becomes trapped during manufacturing or roofing installation. When that moisture heats up under the summer sun, it expands and creates a bubble. The use of automated equipment in shingle manufacturing helps reduce the risk of trapped moisture by improving quality control.
Inadequate Ventilation
Eagan homes with older or poorly ventilated attics may experience excessive heat buildup, which accelerates shingle blistering.
Explore our Eagan roof installation and ventilation services
UV Exposure
Summers in Eagan bring long hours of sunlight. Over time, UV rays break down asphalt shingles, especially when ventilation is poor or shingles are lower quality.
Lower-Quality Shingles
Homes with builder-grade or aging asphalt shingles are more likely to develop blisters. High-quality asphalt shingles have more durable protective granules, which help prevent blistering and extend the roof’s lifespan. Krech Exteriors installs high-quality Owens Corning and GAF shingles engineered for long-term performance in Minnesota’s climate.
The Role of Manufacturing Defects in Roof Blistering
While Eagan’s climate and attic ventilation play a big part in roof blistering, manufacturing defects are another key factor that can’t be overlooked. Sometimes, even when asphalt shingles are installed correctly and the roof system is well maintained, shingle blisters can still appear—often due to issues that started during the manufacturing process.
One of the most common manufacturing defects involves leftover hydrocarbons in the asphalt bitumen, a material created during the crude oil refinement process. If these hydrocarbons aren’t fully removed, they can cause micro-explosions when the shingles heat up under the sun, leading to bubble-like blisters on the roof’s surface. Incorrect mixtures of asphalt and other materials, poor quality control, or inadequate testing during shingle manufacturing can also result in asphalt composition shingles that are more vulnerable to blistering.
Manufacturing defects often reveal themselves early in the life of a roof, or as widespread blistering across an entire slope rather than just a few shingles. If you notice shingle blisters appearing soon after installation, or if blistering is not limited to one area, it could be a sign of a manufacturing defect. In these cases, a roofing contractor can help determine whether the problem is due to the manufacturing process and advise if a total roof replacement is needed to protect your home from premature deterioration.
It’s important to remember that while poor attic ventilation, trapped moisture, and harsh weather conditions can all contribute to roof blisters, manufacturing defects are a common root cause—especially when blistering occurs despite proper installation and routine maintenance. Choosing high-quality shingles from reputable manufacturers and ensuring your roofing contractor follows best practices can help prevent blistering and extend the life of your roof.
Regular inspections are also key. By catching manufacturing defects early, you can address them before they lead to more serious roofing issues, helping to protect your investment and keep your roof system strong for years to come.
Why Blistering Matters in Eagan’s Climate
Blisters may seem like a cosmetic issue at first, but once they pop, they become a serious problem by leaving the roof vulnerable. In Eagan’s freeze-thaw cycle, water can enter these exposed areas and freeze, widening cracks and leading to rot, leaks, or shingle failure. Blistering should be addressed promptly to prevent further damage.
Winter Impact: Snow melt during the day, followed by freezing at night, worsens damage in blistered areas—especially on roofs that are already 10–15 years old.
How to Spot Roof Blistering
Look for these common signs:
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Small raised bumps (often ¼–1 inch) and inspect the affected area for severity
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Irregular placement (not in storm patterns) across the affected area
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Discolored or bare spots where blisters have popped, indicating blister damage
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Deterioration around ridge lines or sun-facing slopes, especially in the affected area
Be sure to look for additional clues beyond these obvious signs, such as hidden blister damage beneath the surface.
Not Sure? Hail damage and blistering can look similar, and an untrained eye may have difficulty identifying hail damage or distinguishing it from blister damage. Avoid unnecessary foot traffic on the roof during inspection to prevent further damage. A professional inspection is the only way to know for sure—and to determine whether the issue is covered by warranty or insurance.
How to Prevent Roof Blistering in Eagan
Blister prevention starts with smart roofing decisions. Asphalt shingle roofs are particularly susceptible to blistering, so extra care is needed:
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Use quality shingles with strong manufacturer warranties
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Ensure proper attic ventilation with intake and exhaust balance, as part of a well-designed roofing system
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Be cautious of two layers of shingles, as having two layers can increase the risk of blistering and make repairs more complicated
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Schedule regular inspections—especially after hot summers or major snow seasons
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Work with experienced, local contractors like Krech Exteriors who understand Eagan’s roofing challenges
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Consider a new roof with high-quality materials and professional installation to prevent future blistering
See why Eagan homeowners trust Krech for roof replacement
What to Do If You See Roof Blisters
If you notice bubbling or suspect damage, especially blister pops or popped blisters, which are signs that immediate attention is needed:
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Avoid walking on the roof—this can cause more blisters to burst.
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Call for a professional inspection to assess roof damage and determine if roof repair is needed.
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Document conditions for your insurance claim and when working with your insurance company, especially if your roof is under warranty.
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Plan your repair or replacement based on expert recommendations.
After a recent storm, be sure to check for storm damage, as this can result in a damaged roof that requires prompt attention.
At Krech Exteriors, we offer free roof assessments for Eagan homeowners, helping you plan smart repairs or insurance-supported replacements.
Request a free roof evaluation in Eagan
FAQ: Roof Blistering in Eagan
Does roof blistering lead to leaks?
Not directly, but once blisters pop, exposed shingle mats can absorb moisture, leading to leaks over time—especially during winter freeze cycles.
Is blistering common in Eagan?
Yes. Eagan’s mix of high summer heat and long winters makes blistering a frequent issue on older or poorly ventilated roofs.
Are blistered shingles covered by insurance?
Not usually. Insurance typically covers sudden damage like hail or wind. Blistering is often seen as a wear-and-tear issue or manufacturing defect.
Can I replace individual blistered shingles?
In some cases, yes. But if blistering is widespread, a full roof replacement may be the most cost-effective solution.
How long should my shingles last in Eagan?
Architectural shingles typically last 25–30 years, but blistering and weather extremes can shorten that lifespan without proper maintenance.
How do gutters help prevent roof and shingle damage?
Gutters play a crucial role in protecting your roof by directing rainwater away from the shingles and foundation. Properly maintained gutters help prevent water from pooling on the roof, which can lead to shingle damage, leaks, and even structural issues during storms or harsh weather conditions. Regular gutter cleaning and maintenance are essential for overall roof durability.
