Fluid-applied air barriers combine resiliency with flexibility to help builders meet codes and environmental standards

The air barrier is an integral component of an effective building envelope, helping architects and builders meet energy efficiency goals and building code requirements. Essentially, an air barrier controls air flow between the interior and exterior of a building.

The air barrier defends against elements that cause structural failures to a building over time, such as water vapour, air and harsh temperatures. As building codes become more stringent, architects and contractors are looking for resilient air barrier solutions that are easy to apply to new building designs.

Fluid-applied barriers are quickly increasing in popularity, thanks to their ease of application over sheet or self-adhering membrane barriers and their effectiveness even on irregular substrates. A recent survey of installers and general contractors found that 62 percent of applicators use fluid-applied air barrier coatings. BASF offers a variety of high-performing polymers that allow formulating fluid-applied air barriers with greater flexibility and adhesion on a wide array of substrates — without compromising on performance.

Building codes and the role of air barriers

Performance requirements for air barriers, measured in terms of air leakage, were first set by the International Energy Conservation Code (IECC) in 2012. Just a few years later, the U.S Department of Energy released the 2015 IECC Commercial Scope and Envelope Requirements with new requirements for older buildings.

According to Antonia Chan, Marketing Manager of Construction Solutions at BASF, that means contractors and building owners are increasingly looking for high-performance air barrier solutions.

“Because these building codes are becoming more stringent, the technologies available to achieve a successful building envelope and airtightness are being tested to higher standards,” Chan says. “That means it's getting harder to construct a building with all the new design aspects architects want, but also meet airtightness requirements set by building codes.”

Older buildings that were not built with an effective building envelope are prone to structural failures and poor energy efficiency, posing both an environmental and safety concern.

“Imagine there's leak in a building that allows air to pass through. That causes damage to the building, which not only loses energy in the building but also fails to meet environmental codes,” says Jackie Murphy, Application Chemist at BASF. “A successful air barrier system has to generate structural integrity and have durability in any kind of weather in different climate zones.”

The rise of fluid-applied barriers

Besides their versatility, fluid-applied barriers are increasing in popularity due to changing architectural preferences.

“Building design is changing, the labor market is changing, and contractors don't have the same time to build a resilient building like they had once before, so these buildings are going up much quicker,” says Chan. “Air barrier technology needs to change along with the times.”

Compared with sheet air barriers, which are applied as self-adhered membranes, fluid-applied air barriers can be easier and faster to apply, saving on labour costs and time.

“In 2019, we conducted a market research study in the United States where we interviewed and surveyed contractors, laborers and architects, and we found out that fluid-applied air barriers were very popular for their ease-of-use compared to sheet membranes,” Chan explains. “Fluid-applied types of air barriers are also expected to continue to be popular in the market and continue to have performance improvements over time. BASF’s chemistry enables the formulation of all different types of fluid-applied barriers.”

Air barrier performance testing

Ease of application for fluid-applied air barriers is certainly an advantage, but they need to be able to perform effectively as well. Thanks to advances in polymers and coating formulations, fluid-applied barriers are just as reliable as membrane barriers. The choice between the two often comes down to a matter of preference from the architect or contractor.

A successful air barrier system needs structural integrity and durability in any kind of weather in different climate zones.

Jackie Murphy

Application Chemist at BASF

“From an effectiveness standpoint the fluid-applied air barrier can perform just as well as a sheet could,” says Chan. “It's really what your architect prefers and how to meet that building code.”

Air barriers are put through a number of strenuous tests to ensure they can withstand the various environmental forces they’ll come in contact with after application. ASTM E96 and ASTM 1305 are two critical tests that evaluate the barrier’s permeability and crack-bridging, respectively.

“We have to make sure that it falls under the criteria of a permeable barrier or impermeable barrier,” says Murphy. “Permeability is one of the things architects are usually looking for when they search for a specific type of air barrier to install, so ASTM E96, water vapor transmission test, is one of the main tests for barriers.”

ASTM C1305, or the crack bridge test, is another important measure of air barrier effectiveness.

“The second test is called the crack bridging test, or ASTM C1305, and it essentially evaluates whether the barrier can withstand extremely cold temperature cycles,” Murphy explains. “In the test, you have two blocks of concrete with the coating applied on top of the blocks, and a machine stretches the blocks back and forth slowly at -26°C. That’s trying to mimic the same vibration that a building would have at extreme conditions.”

BASF’s barrier portfolio

BASF offers a strong portfolio of polymer dispersion products for fluid-applied air barrier coatings that are flexible, weather-resistant and easy to apply with strong adhesion.

“BASF has a portfolio in waterborne dispersions, and for fluid-applied air barriers we have four different types of latexes offered in two different areas: vapor permeable and vapor impermeable,” says Murphy. “Not only can our latex achieve permeability with low water absorption, it also passes the crack bridging tests.”

In particular, Murphy and Chan recommend BASF’s ACRONAL 4511, calling it the “ideal” all-acrylic dispersion for the formulation of permeable air barriers. Air barrier formulations using ACRONAL 4511 feature high water vapor permeability and high flexibility.

As the world becomes more focused on sustainable products, manufactures are placing an increased focus on environmentally conscious products. The latest portfolio of BASF air barrier products is APEO-free, for instance. That said, the performance of these barriers plays a more important role in the form of eco-conscious construction.

“Big picture-wise, this portfolio of products for air barriers supports the greater goal of enabling us to build more resilient buildings — something that we know is very important as we introduce more people into this world,” says Chan. “We're going to have to create buildings that are longer-lasting, more resilient and more energy efficient, so this is all contributing to those goals in addition to the environmentally-conscious chemistry.”

Looking to formulate an air barrier solution? Contact a BASF expert today.

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