Construction Products That Don't Work: Butyl Tape

by Cody Farmer

 In watching the above video (recorded by myself and featuring Master Craftsman, Felipe), you can already see the direction I’m going with this – butyl tape is one of those construction products that needs to die a swift death because it just doesn’t do the job right! I don’t expect you to just take my word as gospel truth, so let’s dive into some facts.


First of all – to be fair - butyl tape is not the worst tape out there – asphaltic tapes are. Asphaltic tapes were one of the first flashing tapes to be used. They are still used today because they are so cheap, but they presented numerous problems including: loss of adherence in high or low temperatures (which is bad news for general contractors in CO), off-gassing of VOCs, degradation issues, brittleness in cold temperatures (again – no bueno for us in Colorado), and loss of resilience due to UV exposure. It was a combination of these issues which led construction experts to start creating a different kind of tape: butyl tape.

Originally butyl tape was created using real rubber, but most butyl tapes now use a synthetic rubber. Although this was originally thought to be an upgrade to asphaltic tapes, experts are discovering that it’s really not much different. Butyl tape withstands temperature extremes slightly better and is slightly more durable than asphaltic tapes, but all of the other problems with asphaltic tapes are the exact same problems associated with butyl tapes.

So, what’s the worst that can happen if you use an inferior tape? When the tape degrades, VOCs can seep into the building through the air and water damage from adverse weather can seep into the walls causing rot, as you can see in the image below.

Air Tight Construction Colorado

So, if both asphaltic and butyl tapes are insufficient, what do we here at Mainstream Corporation recommend? Vapor Open Acrylic tapes…specifically Pro Clima’s Tescon Vana widths up to 2” to 8”, Tescon Invis (all black), and Extoseal (sill pan) tapes. Acrylic tapes solve all of the main problems involved with asphaltic or butyl tapes because they: don’t off-gas, can handle very high or low temperatures, adhere much better, are tough in the face of UV rays, and – if installed correctly – can completely seal the home so that fresh air can be brought in only where you want it to, with an ERV or HRV. This gives you airtight construction in Colorado. This option is much better for the environment, and because it aids in greatly reducing energy costs for the building’s residents, it also will save the homeowner money in the long-run.

I’m sure you’ll agree they are worth the investment when you try them out on your next project!