A lot can go wrong with your roof in the summer. One of those is roof blistering. Roof blisters look like they sound—a lot like human blisters. They look like puffy bubbles that protrude from inside the asphalt shingle. 

Here are some commonly asked questions and answers about roof blistering. 

What are roof blisters?

A roof blister (aka roof ridge) is a volatile gas formed from an asphalt shingle overheating. Or in built-up or modified bitumen roofs (BUR), air pockets are trapped between the plies (roof membrane).

Sometimes, roof blisters fill with water without causing noticeable roof leaks. But if they aren’t repaired before winter weather arrives, the water in the blister can freeze, expand, and split the roof membrane. 

What causes a roof to blister?

Roof blisters can affect your roof aesthetics and performance. But what causes them? 

Defective Shingles

Trapped Moisture. The most common cause of roof blistering begins with defective shingles. Shingles have three layers: backing, asphalt, and granules. If moisture becomes trapped between the layers, they will expand on a hot day. Quality shingles can withstand expansion and contraction. Defective shingles will pop from the slightest impact. 

Degranulation. Inconsistency when applying the asphalt thickness is another reason for blistering. Thin spots can melt in the sun’s heat and lose their grip on the protective granules covering them. The shingles can prematurely fail if the granules are swept away due to UV exposure. 

Improper Roof Ventilation

Excessive heat is brutal on shingles, especially with improper roof ventilation. A well-ventilated roofing system releases heat and moisture from the attic and roof structure to help lower the overall temperature in the attic. When it doesn’t, it can lessen our roof’s lifespan by

Overheating. A poorly ventilated roof in full sun can overheat, causing roof blisters. It can also cause other deformities, such as warped decking or trusses.

Thermal Shock. Extreme and sudden temperature changes, such as a hot day with rain, can cause thermal shock. Shingles can curl or buckle. Poor ventilation increases the chances of this happening, especially with other roofs.  

Adequate roof ventilation is critical, not only for your roofing system but also for your heating and cooling budget. 

Poor Installation Practices 

Improper installation practices can cause wrinkles and roof ridges. 

Nail Pops. Nails that are too short or not hammered securely can pop back up. As it pops out, it pushes the shingle, creating ridges or wrinkles. 

Underlayment Issues. When wet, incorrectly installed underlayment, wrinkles.

Lack of Underlayment. If you notice a picture framing effect on your roof, your contractor didn’t install underlayment, which is not per code. Not installing underlayment is not up to code standards and can affect your roof’s performance and durability.

If you notice one of these issues, contact a reputable roofing contractor to check your roof for other installation problems and fix it immediately. 

Can roof blistering be fixed?

Definitely! Roof blisters can shorten the life of your roof. So fix them as soon as possible so they don’t enlarge or multiply. 

Can I prevent roof blisters?

Yes. You can prevent roof blisters. Poor materials and installation practices are one of the primary reasons blistering happens. Be sure to hire a roofing contractor that won’t cut corners, uses quality materials, and follows approved installation instructions.  

What can I do if I see roof blisters?

Regardless of the issue causing roof blisters or ridges, we recommend calling a qualified roofer to check out the problem areas to evaluate how to repair the roof. 

In the simplest terms, roof blisters happen when poorly ventilated roof systems overheat, causing shingles to malfunction. Call a professional if you suspect roof ridges or if it’s been a long time since you’ve had a roof inspection. 

At Perry Roofing Company, we treat every home like our own. We use premium quality asphalt and metal roofing products. And we are Northwest Arkansas’ premier roof repair and roof installation services. Contact us today for a FREE estimate. 479.306.4327