hail damage to roof

Roof Blistering: What It Is and How To Prevent It

June 2, 2022

Roof Blistering: What It Is and How To Prevent It

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Roof blisters are unsightly and potentially dangerous. Blistering is one of the most common problems with asphalt shingles, and you shouldn't ignore it.

Blistering can affect the performance and lifespan of the shingles. Learn how to identify them and how to fix them before they become a problem.

What Causes Roof Shingles to Blister?

Trapped Moisture

Asphalt shingles may blister due to trapped moisture in the shingle. Moisture can sometimes get trapped inside the shingles during their manufacturing process.

When the sun heats up the shingle, the water trapped inside will rise to the surface. The trapped water will cause the shingle to blister.

Trapped Heat

If there is trapped heat in the attic, the roof temperature can rise to the point where it forms more blisters. Other areas, such as the eaves and siding adjacent to the attic, can also be affected by the trapped heat.

Poor Ventilation

Blistering can also occur when there isn't adequate ventilation in the attic or roof. If the temperature gets too high, the shingles can blister.

This will eventually create blisters on the shingles. Poorly ventilated roofs below the rooftop cause the roof deck to become overheated, preventing the shingles from letting off the heat they absorb from sunlight.

Is Roof Blistering Bad?

Roof Inspection Chalk Marks

If the shingles blister and peel off, they can loosen the waterproofing granules, which help keep water out of the roof. Roofs that lose granules are also more prone to harsh sunlight, accelerating the weathering process even more.

Blisters create a separation between the base of the roof and the shingle, which makes it likely the blisters will pop and make your roof lose its visual appeal. 

Additionally, once the blisters pop, there is more of a risk of water damage inside your home. Blisters tend to wear down roofs faster than they would otherwise.

Blistering occurs when the roofing material loses its protective granules or grit at the blister location, which accelerates UV damage to its membrane. When blisters form, protective roof coatings can become cracked and peel off.

Roof appearance is another matter to consider. If there are multiple holes in a blistering rooftop, they will be easily visible outside. Replacing a roof section could help your home retain its value and beauty.

Your roof is an interconnected system that protects your home from constant assault from the elements. Breaks in the roof systems will ultimately lead to its failure. Roof repair can be expensive, but it's much cheaper than the cost of repairs later on if you don't take care of your roof now.

While the roof repair work must be done as soon as possible, having it be a covered insurance expense is preferable to taking care of it all on your own; thankfully, Melo Roofing is here to help!

Preventing Blistering Shingles

Choosing quality asphalt shingles during a new roof construction can help prevent blisters, as good shingles may be durable enough to at least avoid blister popping. Melo Roofing chooses CertainTeed shingles due to the quality and durability of the product.

If blisters appear, once the vapors contract or the moisture evaporates, the blisters should just disappear without causing any real damage to the roof. There are other ways you can help to prevent roof blisters from forming on your shingles.


Ventilation is one of the essential points you should address. Shingle blisters can be treated, but if the main reason for the blister is not fixed, you'll likely have similar problems in the future.

You should install vents at the ridge of your roof to allow proper venting along with the eaves. Many residential roofs are surprisingly lacking in attic ventilation.


If your home has been without attic ventilation for some time, there's a good chance your attic space may be damaged by moisture, uncomfortably hot spaces, and increased energy costs during summer. Often, moisture leads to mold which can become an even more severe issue.

Ice Dams

Ice dams may form without proper attic and roof ventilation, causing damage to your roof. Ice dams damage the roof on the outside and can cause severe water damage to the inside of your home.

Roof Blistering or Hail Damage?

Blister damage is caused by trapped heat and moisture, while strong winds and hail storms cause hail damage. The damage pattern on the roof indicates whether or not the damage was caused by blisters or hail.

The difference in damage patterns is easily identified when looking closely at the roof. The damage on the roof is often unevenly distributed, but there may be areas where the damage is concentrated. These concentrated areas indicate that the damage was caused by hail.

In the images below, you will see a popped roof blister, which looks like basic damage to the shingle. The hail-damaged shingle image shows that there are granules missing from where the hail damaged the roof.

Roof Blister


Hail Damage

hail damage to roof

Regular Inspections

Roofing contractors should always check roofs for damage early in the season and during rainy weather. They should also inspect roofs after heavy rainstorms. This will allow them to catch problems before they cause significant damage to the roof. 

As asphalt roof shingles age, they can deteriorate, leaving granules in your gutters or downspouts. With a regular inspection by Melo Roofing, the status of your roof will be monitored to ensure your roof continues to protect your home!

Roof Blistering Key Takeaways

  • Most roof blisters are caused by trapped moisture
  • Roof blisters are common, and usually aren't concerning
  • Un-popped blisters can vent out on their own
  • Regular roof inspections can help prevent damage from roof blisters
  • NEVER pop a roof blister (on purpose)
  • Contact Melo Roofing for any concerns about roof blistering