Waterproofing is a crucial aspect when it comes to building structures, specifically for huge residential and commercial edifices. It is why, rather than using an ordinary sealer and paint, builders highly recommend the application of fluid-applied membrane air—as well as vapor—barriers.

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Such waterproofing solutions, however, are relatively new in the construction industry. And many homeowners are not yet aware of the fluid-applied membrane air barrier’s efficiency in terms of controlling the movement of air and water through a building assembly.

And perhaps, you are reading this because you are curious about its function and its benefits? 

What Is a Fluid Applied Membrane Air Barrier?

Per the Air Barrier Association of America (ABAA), a fluid-applied membrane air barrier is a material designed to control the movement of air throughout the building assembly. And for material to qualify as a functional air barrier, it should meet the standard specifications of less than 0.004CFM per square foot @1.56 lb per square foot of air permeance tested by ASTM E2178-01. 

Fluid-applied membrane air barrier was first introduced in the mid-1980s and was originally a Canadian-developed technology for waterproofing and as a part of an initiative to conserve energy. Fifteen years later, it was launched in the U.S. and is now mandated across 12 states under energy codes. 

Moreover, early FAABs were known to be heavy-bodied as well, with thick wet film or dry film application. It is commonly used for large commercial buildings too. And is just one of the several forms of air barrier materials available in the market today such as Prosoco’s R-Guard MVP Liquid Applied Air and Water Resistive Barrier.

Other forms of air barriers include self-adhering sheet goods and mechanically fastened building wraps (commonly used for residential works).

The Difference Between Air and Vapor Barrier

One of the many things home and building owners are confused about wall barriers is the difference between an air and a vapor barrier.

Essentially, an air barrier serves as a tool to limit the movement of air within the building assembly, while vapor barrier curbs the movement of moisture. And compared to the former—which has a permeance of 0.004CFM per square foot—the latter has less than 0.01permeance.

But do take note that there are liquid-applied air barriers in the market today with low permeance and can also qualify as a vapor barrier. Meanwhile, choosing which barrier to use will depend on the typical weather in the area the structure is located. Wall design must also be considered.  

The Perks of Using Fluid-applied Membrane Air Barrier

Unlike other forms of air barrier, the fluid-applied membrane air barrier is the most popular—and for many good reasons. The material basically provides a number of perks that are beneficial to both commercial and residential works. And one aspect that makes it truly stand out is it is convenient to apply.

But that is not the only perk liquid-applied membrane air barrier offers.

Here are a few more:

  • Affordable initial construction cost. Because the material prevents air leaks such as from the air conditioner, the mechanical system—particularly heating and air-conditioning systems—that is needed for the building is small. In return, it lowers the cost of construction for the said system. 
  • Easy to apply. Perhaps the best thing about a fluid-applied air barrier is it is very convenient to apply. It is because compared to other air barrier materials, it does not involve a multi-step process and can be simply applied using an airless spray, a paint roller, or a v-notch trowel.

    Essentially, its application process is ideal for starters. And unlike other forms of air barrier, it provides coverage of caulked joints, flashing, terminations, and differing substrates. In fact, it has a structural bond to the substrates.
  • Helps to save energy. One of the reasons why the application of air barriers is important is because it is mandated across the 12 states of America under the energy codes. It is also mentioned that the material was developed as an initiative to save energy. Thus, essentially, a liquid-applied air barrier can help conserve energy.

    According to DOE, the management of air movement and preventing air leakage throughout the building assembly can lower the energy costs by 40%. It also lowers gas and electric consumption by up to 40% and 25%, respectively, according to the National Institute of Standards and Technology (NIST).
  • Improved indoor air quality. Aside from lowered energy consumption, affordable construction cost and easy application, a fluid-applied air barrier enhances indoor air quality as well. Air barriers are effective at blocking pollutants as well as allergens out of the building or house.

    In offices, improved indoor air quality leads to healthier employees and fewer sick days. It is beneficial for people with asthma or other lung-related medical conditions. And given that it prevents allergens and pollutants, it is also crucial for houses with people who have allergies. 
  • Lower maintenance cost. Last but not least, it has a low maintenance cost. According to AABA, a fluid-applied air barrier has less strain on mechanical systems, which will cost you significantly if damaged. Less moisture also prevents mold growth and corrosion.

Are There Drawbacks?

Just like any other product, a liquid-applied membrane air barrier has disadvantages too. These include the need for a skilled and professional person and higher high costs.

Here’s why:

  • Requires a skilled applicator. To make sure that the material will work efficiently, the solution must be applied evenly. As such, it will not only require a specialized tool like a spray gun, but it will also need a skilled and experienced person who can apply the air barrier with precise thickness.

    But the thing is, there are not enough qualified folks who can do such a job. And finding one would be difficult.
  • High application cost. Because there is a shortage of qualified and skilled air barrier applicators, hiring one would definitely cost you a significant amount of money. The material itself is relatively more expensive than other air barriers sold in the market today as well. 
Editorial Contributors
Matt Greenfield

Matt Greenfield

Matt Greenfield is an experienced writer specializing in home improvement topics. He has a passion for educating and empowering homeowners to make informed decisions about their properties. Matt's writing focuses on a range of topics, including windows, flooring, HVAC, and construction materials. With a background in construction and home renovation, Matt is well-versed in the latest trends and techniques in the industry. His articles offer practical advice and expert insights that help readers tackle their home improvement projects with confidence. Whether you're a DIY enthusiast or a seasoned professional, Matt's writing is sure to provide valuable guidance and inspiration.

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