Butyl sealant: A critical component in metal roofing

By Ali Turner, Content Writer, S-5!

Discover the power of butyl!

Are you familiar with butyl sealant? Perhaps you’ve heard of it, and maybe you’ve even used it. For those new to metal roofing, butyl might be a new concept for you. This blog will introduce you to butyl sealant and explain why it’s so important in metal roofing applications.

Butyl is a synthetic rubber developed in the early 20th century. A particular variation of this broad category is a copolymer of isobutylene and isoprene, and it's created through a chemical synthesis process. This non-curing polymer has a gum-like consistency and maintains its tackiness throughout its decades-long lifespan. Its primary job? Establishing a durable barrier to keep moisture out. Be aware that not all butyls are equal, so simply labeling “butyl” doesn’t really mean much. Numerous chemistries, all called “butyl,” are out there and can NOT perform the same. As long as it has an isobutylene component, you can call it “butyl” for marketing purposes. And the manufacturing companies will not reveal their “secret sauce,” so all you have to go by is how long those formulations have been successfully used on real roofs with satisfactory performance.

Butyl and metal roofing: A dream team

On exposed-fastened metal roofing systems, ensuring a watertight seal is critical. By using the right butyl copolymetric seal on brackets, the risk of leaks is minimized. Butyl-enhanced brackets combined with EPDM fastener washers done the right way can form a triple seal, providing added protection against the elements. This airtight, watertight sealant establishes an impervious moisture barrier.

Furthermore, the “right way” fasteners with an EPDM washer and stainless top offer a triple seal when used in conjunction with the right butyl polymer-sealed brackets.

Learn why verified testing is the only way to prove your metal roof won’t leak.

Benefits of butyl

The right butyl sealant formulations are weatherproof and last a long time, upwards of 60 years! Isoprene-butylene polymers in the right combination are flexible and can conform to the surface irregularities on your metal roof, always ensuring a tight seal. Additionally, by not using a messy, field-applied sealant, metal roofing contractors have the peace of mind that they’re getting a complete assembly without having to source ad-hoc sealant materials.

How to apply like a pro

While “butyl” (when in reference to the right chemistry) is a superhero in the world of metal roofing, it does have one kryptonite: the sun. When exposed to UV sunlight, butyl sealant can dry out and fail. However, when products are designed The Right Way™ and butyl is protected from UV exposure, the sealant retains its tackiness and elasticity. For butyl sealant to work properly, it needs to be placed on a clean surface free from dirt and debris.

Quality matters

Not all butyls are created equal. They are brand-proprietary and vary widely. It's crucial to source from a reputable manufacturer with proven performance. Yes, butyl sealant has risen in popularity over the years due to its ease of application and impressive service life but be warned there is no shortage of imposters out there. We have seen some butyl brands fail miserably within 10 years. Sadly, many metal roof attachment manufacturers rely on butyl brands without knowing their track record of performance over an extended time.

To the left, we can see a picture from a forensic investigation of a 33-year-old metal roof in Denver shows the excellent elasticity by the butyl sealant that was used.  

Ideas to hold on to

As the popularity of butyl sealants continues to rise in the metal roofing industry, it's critical to know the difference between quality products and “me-toos.” So, while it’s true that the increased use of butyl is a positive for the solar industry, The Right Way is to source by first-hand experience with brands and formulations with at least 40 years of proven field performance.

Visit www.s-5.com to browse our attachment solutions and be sure to enroll in S-5-University™ to become a metal roofing expert.