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What is a Shingle Manufacturing Defect?

May 14th, 2024 | 3 min read

By Jeffrey Linta

Roof shingles on a conveyor belt at the manufacturer

What is a manufacturer's defect?

And how can I be sure my shingle manufacturer will be accountable for a material defect if I have one?

When choosing a roof warranty you may hear glowing promises of a manufacturers’ warranty. But when you have damage on your roof, you may wonder if your shingle manufacturer will honor that promise. If materials fail, it is important to have a roofer come inspect the damage to assess whether it is caused by poor workmanship or a manufacturers’ defect. 

If you had your roof installed by a reputable roofing company, it is unlikely that you would have major issues with your roof for a long time. This is why it is so important to nail down the cause of the roof damage so you don’t get stuck with the bill. In this article we will talk about the most common manufacturers’ defects and exactly how they can negatively impact the quality of your roof.

A manufacturing defect refers to any flaw or imperfection in roofing materials that occurred during the manufacturing process. This defect can result in substandard performance or premature failure of the roofing system. 

The most common manufacturers defects include:

  • Sealant Failure 
  • Thermal Cracking
  • Discoloration
  • Blistering
  • Degranulation

Let’s take a look at these defects, so you know exactly what your warranty covers.

Most Common Shingle Manufacturers Defects on a Roof

Catching roof defects early could save you quite a headache. When parts of your roof fail, you could ultimately have to remedy interior damage. This can be time consuming and very frustrating. Not only that, but if you’re unaware that your warranty covers the issue on your roof, you may spend an unnecessary amount of money repairing it. 

Some of these issues can be more common than others, but let’s break down some of the most common manufacturing defects we’ve seen in our 39+ years of roofing experience.

Sealant Failure iStock-1050091180

When shingles are applied to a roof, it generally takes a day or two for the shingles to seal together. Shingles have an adhesive strip that keeps them working together as a cohesive unit. If your shingles do not seal and your roofer installed the materials within the manufacturers’ guidelines, this is likely a sign of a manufacturers’ defect.

Thermal Cracking cracked asphalt roof shingle

Shingles cracking can happen naturally if your shingles are old, however newer roofs should not have this problem. If you see cracking on your shingles only a few years after installation, it could be that the necessary coating to protect your shingles from UV rays was not applied during the manufacturing process.


Your roofer should always check the lot number on shingle bundles. This step is important because different lot numbers can vary in color. If all of the shingle bundles that were applied to your roof have the same lot number, but you see different colors/shades, this is likely a labeling issue from the manufacturer.


While blistering is more commonly a result of a faulty roof installation, it can also be a result of improper mixing of materials or inadequate curing during the manufacturing process. Blistering refers to the formation of bubbles or raised areas on the surface of the shingle.

Degranulationroof shingle granules coming off

Asphalt shingles have granules applied to them during the manufacturing process. This is to enhance their durability and improve aesthetic appeal. Degranulation is usually a gradual loss of granules from the shingle surface. Some degranulation is natural after the initial install. This is usually due to your roofers walking around on the shingles to complete your roofing project. Additionally, you may notice granules in your gutters after a heavy rain storm. Both of these types of degranulation are natural and normal. However, if there is excess degranulation when your roof is new, this could be a sign of a manufacturers’ defect. 

How to Resolve a Manufacturers Defect on Your Roof

It may seem like it would be a difficult task to have your shingle manufacturer take accountability for an error that occurred in their factory. However, this is not always the case. In the event that your roofer is certified with the manufacturer, your roofer may be able to effectively advocate for you. 

Certified roofers are a manufacturers’ best customer. Manufacturers have a vested interest in maintaining a good relationship with roofers who use their products. So, in the event that your roofer believes you have a manufacturing defect on your roof, the manufacturer will come out to do an additional inspection. If it is determined by both that the issue is not a workmanship issue or a weather related problem, but rather a material defect, your warranty may cover the costs associated with replacing your roofing system. 

However, if your roofer is not certified, they may have a more difficult time through this process. When it comes to finding a trustworthy roofing company, make sure to check their certifications. This little bit of extra research can save you a lot of time, money, and hassle in the future!

Jeffrey Linta

Jeffrey Linta is a 3rd generation roofer who grew up working in his family's roofing business (Linta Roofing, Inc.). He got his start tearing off roofs during the summer while attending North Myrtle Beach High School. Now running one of the most successful roofing businesses in the Grand Strand area, Jeffrey has lived and breathed roofing for his entire working career. Some of his accolades include GAF Master Elite Contractor, SC Safehome certified contractor, Group 5 SC Licensed Commercial Contractor, and GAF Master Commercial roofing contractor. Under his leadership, Linta Roofing, Inc. has served thousands of homeowners and business owners in the Grand Strand area. Linta Roofing achieved awards like the Sun News’s “Best of the Beach” and A+ Rating with the Better Business Bureau all while receiving hundreds of 5-star reviews year after year. Jeffrey is a Grand Strand born and raised local. When he is not running Linta Roofing, he spends time fishing with his wife Erica and walking the beach with his dog Dixie.