Roof Blisters 101: Ultimate Facts and Guidelines by Professional Roofers

No matter how efficient and durable your roofing system is, it’s bound to develop issues due to the ranging storms, age, and the scorching sun. One of the most nagging roof problems you will likely encounter is roof blisters. Understanding roof blisters, their causes, and how to prevent them is the best way to deal with this kind of problem. Here is the ultimate roof blister guide by the experts.

What are Roof Blisters?

Blisters form when moisture or air is trapped between the shingles or the layers of your roof. In built-up or modified bitumen roof membranes, air or moisture is trapped between the roof membrane. When it comes to asphalt shingles, volatile asphalt gas formed due to overheating in the shingle is trapped between the layers. Typically, roof blisters start as lamination voids before expanding over time as outdoor temperatures continue to rise. Sometimes, the blisters fill with air and cause roof leaks.

Roof blistering is a serious problem that should be addressed quickly before your roofing system becomes weak. When the weather turns cold, the trapped air in the blister might freeze and expand. Over time, it will split the roof membrane.

What Does Roof Blistering Look Like?

Roof blisters look like raised dimples on the surface of your roof. You will also notice a loss of asphalt around the blisters.

Do Roof Blisters Shorten the Lifespan of a Roof?

Unfortunately, roof blisters can shorten the lifespan of your roof. This is because blisters tend to stretch the surface of your roofing material. With time, this will lead to the loss of protective granules or gravel surfacing, exposing the roof to UV damage. Failure to address this problem right away will cause the protective roof coatings to crack and fall off eventually.

Luckily, roof blisters do not necessarily reduce the lifespan of flat roof systems. Moreover, roof blisters don’t become large enough to compromise roof flashings, seams, or laps. In fact, some roof blisters tend to last the roof’s lifetime without causing significant problems.

Does Insurance cover  Roof Blistering?

Since homeowner insurance typically covers roof damage caused by extraordinary circumstances, most roofing manufacturers don’t cover it under the roof warranty and workmanship guarantee.

What Causes Roof Blisters?

Roof blisters emerge for various reasons ranging from installation to extreme weather conditions. Let’s discuss the causes of roof blisters in detail below.

Poor Workmanship

One of the leading causes of roof blistering is poor installation. Blisters might emerge if the roofers fail to pay attention when fixing the materials, applying adhesion, or taking measurements.

Rain During Roof Installation

Installing a roof while it’s raining can also cause roof blistering. Raindrops can sneak in and get trapped between your roofing membrane or shingles. Over time every trapped rain drop can turn into a roof blister.

Poor Attic Ventilation

Due to increased outdoor temperatures and excessive sun exposure, the trapped moisture will expand and form roof blisters. As temperatures continue to rise, the pressure in the blisters might increase and weaken your roofing material.

Extreme Weather Conditions

Extreme weather conditions, such as wild windstorms and heavy snowfall, leave your roofing material susceptible to damage and blisters.

Roof Blisters in Asphalt Shingles

Lack of enough ventilation exposes your asphalt shingles to rising outdoor temperatures and scorching sun. With time, the asphalt material might overheat and release small amounts of gas. These gases might be trapped between the shingles, forming roof blisters.

Although manufacturers have fine-tuned the process, asphalt shingles still operate under specific temperatures. Unfortunately, warranties don’t cover damage caused by temperatures exceeding normal levels. Roof blisters don’t necessarily cause roof leaks, but they can be unsightly and might reduce your roof’s lifespan.

Blisters cause loss of granules, exposing your asphalt shingles to the elements and harsh UV rays. When left unattended, UV rays will break the long hydrocarbon chains making your shingles weak. The reinforcement mat might also be exposed to water damage. Roof blisters on asphalt shingles are hardly covered unless you prove that your roof is perfectly ventilated.

professional roofing contractor repairing a roof

Roof Blisters in Built-Up Roofs

Blistering in built-up roof systems is often caused by poor workmanship during installation. Usually, blisters emerge if the roofer applies the hot bitumen when it’s too cool. Also, blistering might occur if the roofer walks on the newly installed felts. Installing wrinkled felts can also cause roof blisters.

Fortunately, roof blisters are rare in built-up systems. Even if they occur, they rarely lead to roof leaks or other roofing problems. Even so, you should never walk on blisters or pop them.

Roof Blisters in Modified Bitumen Roofs

According to research, roof blistering is more common in SBS-modified membranes than in APP systems. Typically, blistering occurs due to voids in the system. Voids result from entrapped debris, unrelaxed membranes, trapped gases, and improper bitumen mopping. Blisters in a modified bitumen roof are rarely covered under the manufacturer’s warranty.

Final Thoughts

If you are dealing with roof blisters, addressing the issue right away will save you money and prevent further damage. To learn more about roof blisters, call Lone Star Roofing today.