Roof shingle blisters

I believe these shingles to be only about five years old. What do you think is causing this.

defective product…

I agree with Mark


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Blisters in shingles
or “rash blisters” are a cosmetic defect in the opinion of some roofing manufacturers and an indicator of reduced shingle life in the opinion of some building professionals. In the photo shown here, some blister tops have lost granules and are beginning to expose the shingle interior substrate. These Atlas™ roof shingles are less than one year old.

Rash blistering considered cosmetic: Atlas roofing has offered reassurance to their customers by indicating that rash blistering is an aesthetic characteristic only. Atlas roofing does not classify blistering as a manufacturing defect. The company has said that rash blistering will not affect the intended performance or life of the shingles and that the shingle warranty will not be affected.

Photo and explaination here to better explain Blisters;

I have seen anecdotal evidence in Florida that this possible latent condition is exacerbated by the sun / heat. I have seen south west facing roofs riddled with ‘blisters’ while the opposing, identical surface in free from them. It is more than cosmetic IMO, as the degradation accelerates as the ceramic granuals de-bond and flake off.

Jeff Tatlock
BEACHSIDE Home Inspection
Serving Brevard County FL. Areas include Cape Canaveral, Merritt Island, Cocoa Beach, Satellite Beach, Indian Harbour Beach, Indialantic, Melbourne Beach, Viera, Melbourne.

It should depend on who makes them. My good freind is a roofer and we were talking about the faux arc shingles or 3 tabs like marcels pic. I had the same thing last week. Many seem to do this and seem to be junk. They look good for the first few years then start falling apart. My shingles were loosing grit and blistering.
The real kicker is unless the roof is installed to manufacturers specs, then they wont touch it. Of course we all know most never install to manufacture specs.

Thanks for the responses

They ain’t making them like they used to!!

Remember that just 10 years ago, oil was running $10/barrel and recently it’s $75-85/barrel. Where does the asphalt come from…OIL…maybe a bit of profit incentive to cut asphalt quality or use fillers in the asphalt…I’ve heard it mentioned!!

Blisters are usually the result of volatiles flashing out of the asphalt due to poor ventilation. Since asphalt mixes vary among manufacturers, some types of shingles are more likely to blister than others.

It’s basically a cosmetic issue, shingles are unlikely to leak. As has been mentioned, manufacturers are not likely to call it a defect and replace the affected slopes.


You’re listening to the manufacturers too much!!! Ventilation for heat dissipation doesn’t do much unless there are strong winds. Armin Rudd, an associate of Joe Lstiburek’s at Building Science Corp, did some studies of roof temps at the shingle surfaces (the hottest part of the shingle) in Jacksonville, Florida and found that shingles on vented roofs were only 2-3F cooler!! If 2-3F is the difference between failure and success…

From the Inspectopedia site:

“*Unfortunately, on some roofing shingles asphalt shingle bumps or blisters that may appear early in the life of the product or may even be present when the bundle is unwrapped sometimes convert into wear pits when the tops of each blister give up their mineral granules to the weathering process before the remaining area of the shingle.” *

“Reader Marcia Reid]( provided these photographs of blisters on an 8 1/2 year old IKO Asphalt shingle roof in Saskatoon, Saskatchewan, Canada.”

A roof in Saskatoon on the hottest summer days there would be cooler than the temperature of a vented roof in Florida on most cooler days of summer. So what’s the problem…relatively speaking, the Saskatoon roof is a cool roof but it still has the blisters!

BTW, IMHO, IKO has a design or manufacturing problem. I’m seeing curling on 25 year warranty shingles in 6-9 years in our very temperate climate. CBC TV’s “Marketplace” consumer show website has a section (BUSTED) on shingle problems:

Dr. Bill Rose (another of those Phd. Building scientists; U. of Illinois at Champagne) had a short piece in The Journal of Light Construction Q&A page on roof venting. etc. His conclusion is the manufacturer’s are doing everything they can not to honour shingle warranties. He says they should concentrate on putting out good products

My information comes from an awful lot of sources but especially from Ric Vitiello, Benchmark Services, who has made his living for a long time as a roof consultant and expert witness in cases involving some residential, but mostly commercial roofs. Ric has done a lot of field work, lab work and lecturing to members of the insurance industry as a neutral third party.

There are a lot of theories out there and I have a lot of respect for those of Joe and the Building Sciences Corp. I have a lot of respect for the Inspectapedia site too, but they’re pretty far from the last word on roofing.

The effectiveness of a roof ventilation system will depend on the type of system and its components, the home roof configuration, the home location and home’s orientation to the prevailing winds.

I just finished 14 months of research and writing on roofing and one thing I learned is there there are many, many variables. You can give an answer to a post based on a best guess, but to give the best answer possible you need to fill in as many blanks as possible. Usually those blanks are not filled in when someone starts a thread, so when I post a response, it’s usually along the lines of “this is where you might start looking for an answer” not “this is the answer”.

The difference is if you’re investigating to find an answer, or if it’s a condition you’ve dealt with before, the blanks are filled in and you know the answer. Sometimes you think the blanks are filled in correctly, but unless you are personally visiting the site, you often can’t be sure.

I work pretty hard to stay neutral. Manufacturers are a good source of information, no doubt about it, but you have to remember that they’re biased. At this point my sources cut across a large cross section of the roofing industry. They almost all (except the roof consultants) have some bias because they’re almost all in a roofing-related business. Dealing with the bias of your source is part of doing research.

Blisters in modern shingles typically show up within the first year. That’s not to say they always do, but chances are good that if they make it through the first year without developing blisters, chances are good that they won’t as long as basic conditions stay pretty much the same.

My guess would be that they have a problem with their apshalt mix. Asphalt is becoming more expensive as refining techniques improve and asphalt allocacation programs are put into place by asphalt producers.
Increasing asphalt prices are causing manufacturers to look for ways to cut costs.
Poor asphalt mixes can result in premature evaporation of volatile compounds, leaving shingles drier and more likely to absorb moisture, which, along with differential drying, causes shingle distortion (curling).

"*In the future, asphalt-saturated felt underlayment will probably be used less and, by 2014 it will likely no longer be installed at all. Asphalt is basically the residue left over from the process of refining crude oil. As the price of oil has increased, refining techniques have been developed that extract the maximum amount of high-quality products from the crude. *

These techniques, involving the use of coker units, result in a residue of powder instead of the sludge from which asphalt is normally produced. With less asphalt being produced, an allocation program has been established for which the asphalt produced each year is allocated in limited amounts to manufacturers of asphalt shingles and underlayment."

It’s a tough business and that sounds like an oversimplification. My feeling is that most roofing manufacturers, the major ones anyway, will honor their warranties pretty consistently, but once you get into grey areas, and they do exist, that they are willing to fight harder in a tough economy to win if they think they’re right. If the question is open to interpretation, they try to insist that their interpretation is the right one. What policy would you set if you were the CEO of a successful corporation?

I’ve spent a lot of time this year on the phone with techs from CertainTeed and GAF/ELK and few others. Mostly, they’re very helpful and straightforward. I developed respect for those companies for the quality of techs and information they make avvailable to the public for free. I didn’t always agree with them and sometimes disagreed strongly, but never felt like they were trying to hide anything. They took a position and defended it.
Smaller manufacturers have a more difficult row to hoe and are less likely to be honest and helpful because they aren’t solid in the marketplace.

Warranty terms are usually spelled out clearly, but warranty terms vary a lot and a consumer has to read the policy carefully. It’s a lot of tiny print and it’s easy to miss or misinterpret something. Consumers often have a salesman in the room paraphrasing the warranty and maybe not always accurately. As a consumer, to understand the limits of a warranty you need to sit down and read it carefully and get your questions answered until you really understand it. Consumers are often lazy or ignorant and don’t do this. For this reason, I think the fault is often with the consumer. That’s an unpopular position to take, but what is correct and what is popular are often two different things.

Popular perceptions are one thing and the truth is often otherwise. The truth is often difficult to find and you often have to work hard to find it. You don’t get it handed to you on the TV news or on television magazine shows. The harder you work, the closer you get, and sometimes you find that the popular ideas you once held are wrong, or at least not nearly as right as you thought.

I agree Mark.

Me too!