SpecTips: Choosing the Appropriate Air and Vapor Barrier for Your Project's Conditions

Torch Grade Air and Vapor Barriers

Air and vapor barriers have grown in popularity over the last several years and have become a necessary component in roofing systems, especially in colder climates. This is due in large part to their ability to stop vapor drive as well as prevent moisture-laden air movement into the roofing system, which can lead to premature roof failures resulting from condensation. 

Deck type, weather conditions, and other jobsite conditions must be considered when deciding which air and vapor barrier is best to use for each project. While peel and stick air and vapor barriers are the workhorse in the roofing industry, their effectiveness can be diminished based on the aforementioned project conditions. Cold temperatures, foot traffic, and the presence of moisture on the deck may cause challenges for peel and stick installations.

When temperatures fall below 40°F (4°C) or morning dew is present, a better air and vapor barrier option may be a torch grade modified base ply. 

Using the torch to activate the asphalt helps lower the application temperature down to 25°F (-4°C), making them ideal for winter installations. The “softening/melting” of the asphalt will give a higher degree of coverage than peel and stick, minimizing the potential for moisture/vapor to accumulate in small unadhered pockets between the membrane and concrete, particularly if the concrete is rough. The SBS asphalt allows torch grade air and vapor barriers to provide stronger, heat-welded seams which is especially beneficial in colder temperatures. The reinforcement used in torch grade base plies offers additional protection, making them a great option for projects looking for a temporary roof.

Carlisle SynTec Systems offers two torch grade base ply products designed to provide lasting air and vapor protection for roof installations. Carlisle’s SureMB 90TG provides 90 mils of protection and can be included in Carlisle’s Total System Warranties up to 20 years. Carlisle’s SureMB 120TG provides 120 mils of protection and can be included in Carlisle’s Total System Warranties up to 30 years. Both products are UL Classified and Factory Mutual Approved. They can be installed over primed concrete, mechanically fastened or adhered base plies, or gypsum coverboards such as DensDeck^® Prime or SECUROCK^®. 

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SPECTIP
In 3-Part Specifications – Division 7 section for the membrane being used on the project (07523 – EPDM, 075419 – PVC, and 075423 – TPO). 

Part 2 “Products” – Air and vapor barriers section, include torch grade base ply products. 

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For more information, check out these product data sheets.

SureMB 90TG Base Ply Product Data Sheet
SureMB 120TG Base Ply Product Data Sheet