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Posted by McElroy Metal ● Nov 23, 2021 8:00 AM

Metal Roofing Sealants

Sealants are important components of a metal roof system that can impact the overall roof performance. Some sealants are applied underneath metal components and hidden from view while others are designed and applied with aesthetics in mind because they can also help improve the appearance of a roof.  In all cases, sealants need to be properly applied to be effective, so installation is key for optimal system performance.

Butyl Sealants

IMG_7336 croppedLet’s start with Butyl sealants, which are the behind-the-scenes workhorse of a metal roof system. Butyl sealants are always applied to metal-to-metal connections in areas that may be prone to water intrusion. Butyl sealants are available in both tape and pump-able versions.

Butyl sealant's sole purpose is to prevent the intrusion of water between two pieces of metal. Without butyl sealants, capillary action, or draw could result in a leak as shown in the below drawing on the left. Simply placing butyl sealant between the two panels improves weather-tightness.

Panel-lap-without-sealant-vs-panel-lap-with-sealantThe images below demonstrate how butyl tape should be applied on the underlap of a corrugated metal panel.


Prolonged exposure to UV light (sunlight) will degrade the sealant, so butyls are not intended for applications that leave the sealant exposed to nature’s elements. Properly applied and unexposed to UV light, butyl sealants never cure, or harden, which makes them an excellent sealant for long-term protection against water intrusion.

The list below shows some common metal roofing details where butyl sealants are used.

  • Panel side-laps
  • Panel end-laps
  • At eave conditions
  • Valleys
  • Ridge

Non-Butyl Sealants

Polyurethanes, tri-polymers, and hybrids are commonly used for applications that leave the sealant exposed to nature’s elements. Because they are exposed, these sealants are often colored to better blend with painted panels and trim. Some sealants are also available in translucent/clear, as well as paintable versions. Common uses include ends of panels, reglet flashings, and around pipe boots.


The photo above shows some examples of sealants that can be exposed to nature’s elements. The sealant on the left is available in many colors to better blend with painted roofing panels and trim. The middle sealant is paint-able to enable roofing contractors to match any roof panel color and the sealant on the right is translucent or clear.

In all cases, McElroy Metal recommends utilizing sealants that are specifically designed for use with metal roofing. Some sealants, such as silicone, contain acids that could cause corrosion to metal panels. Sealants formulated for metal roofs should be labeled as such and should perform as expected.

Final Thoughts

All sealants have varying limitations with regard to temperature limits for application, proper storage, and shelf life. Users should be sure to check individual sealant labels for details prior to installation. 

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About McElroy Metal

Since 1963, McElroy Metal has served the construction industry with quality products and excellent customer service. The employee-owned components manufacturer is headquartered in Bossier City, La., and has 14 manufacturing facilities across the United States. Quality, service and performance have been the cornerstone of McElroy Metal’s business philosophy and have contributed to the success of the company through the years. As a preferred service provider, these values will continue to be at the forefront of McElroy Metal’s model along with a strong focus on the customer.

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