September 15, 2020

Fluid Applied Air Barrier vs. Sheet Applied Air Barrier Membranes


For our final blog post of September 2020, we dive into the difference between Fluid Applied Air Barriers (FAAB) and Sheet Applied Air Barriers (SAAB). There are several factors that influence a building designer and contractor’s decision when making the choice between a fluid or sheet applied air barrier system. In order to achieve an efficient exterior wall system, these factors include, substrate materials, building geometry, project conditions, weather conditions, climate, time, whether the air barrier should also control water vapor and lastly, personal preference.

A 1970 Canadian developed technology, FAAB can be spray-applied or rolled onto the wall substrate, providing labor savings during installation. On the other hand, SAAB allow for the membrane to fully adhere to itself and surface materials (such as metal, concrete, sheathing etc.), eliminating membrane tears/ blow-off before installation. SAAB include two choices: mechanically attached and self-adhering.

Unlike Sheet Applied Air Barriers, Fluid Applied Air Barriers easily adept to complex substrate geometry and are efficient at adhering and waterproofing various wall conditions and penetrations (such as brick tiles or electrical conduits). Compared to SAAB, FAAB also provide an ease of detailing at wall openings, fasteners, and repair locations and conform to uneven substrates. For each penetration change, SAAB need to be cut, folded, lapped and sealed. 

Successful applications of Fluid Applied Air Barriers depend on the expertise and abilities of applicators to maintain consistency in mil thickness of the membrane and proper coverage at detail interfaces. On the contrary, since the Sheet Applied Air Barriers (self-adhered) manufacturers guarantee a minimum thickness of the membrane, this reduces the possibility of applicator issues during the installation process. However, SAAB’s labor intensity and difficulty associated with applying and adhering to uneven substrates make it a less desirable choice in most cases compared to FAAB.

To learn about our fully engineered and compatible products that work together to provide air and vapor barrier protection for your building envelope, visit our website at


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