{"id":15296,"date":"2012-12-01T12:00:52","date_gmt":"2012-12-01T17:00:52","guid":{"rendered":"http:\/\/www.constructionspecifier.com\/?p=15296"},"modified":"2016-02-19T15:36:50","modified_gmt":"2016-02-19T20:36:50","slug":"testing-fluid-applied-air-and-water-barriers","status":"publish","type":"post","link":"https:\/\/www.constructionspecifier.com\/testing-fluid-applied-air-and-water-barriers\/","title":{"rendered":"Testing Fluid-applied Air and Water Barriers"},"content":{"rendered":"
\"All<\/a>
All images courtesy Simpson Gumpertz & Heger<\/span><\/em><\/figcaption><\/figure>\n

Fluid-applied air and water barrier products have rapidly gained market share in many areas of the country, but they are still relatively new to the industry. It is perhaps unsurprising then that various failures of these products have been seen during their installation.<\/p>\n

\"A<\/a>
A large, water-filled blister in a cured membrane after\u00a0a rain event. As with all photos in this article, the image is presented in black and white in order to prevent product identification.<\/span><\/figcaption><\/figure>\n

The opportunity to observe these conditions is relatively narrow and usually occurs in the first few weeks of application before the exterior cladding is installed over the barrier. The most significant of these issues include cured membranes developing large water-filled blisters (Figure 1) or sliding off the wall (Figure 2). These failures occurred after the membrane had been installed for at least two weeks and immediately following rain. Their occurrence indicates excessive water absorption leading to poor adhesion, or reversion of the membrane to a fluid-like state.<\/p>\n

Other shortcomings observed in the field include tearing of the membrane along the edge of self-adhered flashing, and alligator cracking of its surface. The first is symptomatic of poor elongation properties of the membrane, while the second is likely caused by excessive ultraviolet (UV) exposure.<\/p>\n

Currently, the industry has few standards addressing the durability of these products, particularly when exposed to moisture over the long term. Many of these assemblies serve as the water-resistive barrier (WRB), as well as the air barrier for the wall. The Air Barrier Association of America (ABAA) evaluates fluid-applied systems by testing air permeance, water resistance, fastener sealability, adhesion to substrates (i.e.<\/i> pull adhesion), and crack bridging.<\/p>\n

The water resistance testing\u2014per American Association of Textile Chemists and Colorists (AATCC) 127-03, Water Resistance: Hydrostatic <\/i>Pressure Test<\/i>\u2014gauges the cured membrane against hydrostatic pressure for five hours. In reality, many membranes will be exposed to moisture for much longer than this period, particularly when used in the wet zone of the wall assembly. While the ABAA evaluation addresses initial performance, it does not deal with long-term durability issues. Even so, widespread project failures are observed even with products that have been evaluated, and approved,\u00a0by ABAA. Although ASTM is developing a standard for fluid-applied air barriers, it does not currently address durability issues for these products.<\/p>\n

\"Cured<\/a>
Cured membrane washed off walls after rain.<\/span><\/figcaption><\/figure>\n

Given the relatively short track record of these products and the failures observed with some, it seemed prudent to develop an in-house program of laboratory testing to better assess their prospects for long-term performance. For practical reasons, the testing program was limited to products from four manufacturers that were early leaders in the fluid-applied air barrier market.<\/p>\n

Both vapor-permeable and vapor-impermeable products from each manufacturer (including two vapor-permeable ones from the same company) were tested for a total of nine. These materials included membranes that exhibited those aforementioned problems in an attempt to replicate the failures in the laboratory and confirm suspected mechanisms. The ultimate goal was to have a basis for deciding their prospects for long-term performance in lieu of a historical track record. This is particularly important since many building owners are interested in using these products; furthermore, many contractors are requesting these materials as alternates to more time-proven products such as self-adhered membranes.<\/p>\n

Lab testing of fluid-applied air barriers<\/b>
\nTo achieve the set goals, testing focused on three important performance properties: pull adhesion, flexibility (i.e.<\/i> elongation), and water absorption.<\/p>\n

Pull adhesion<\/i>
\nFor a membrane to successfully perform as an air barrier, it must exhibit adequate adhesion to the wall substrate. The membranes were tested for adhesion to several common materials.<\/p>\n

Flexibility<\/i>
\nThe membrane must span joints in sheathing boards, and joints between dissimilar materials, such as at flashings. These joints experience minor movements through the life of the building. Since the membrane must provide a continuous barrier, and not split or tear under these movements, its flexibility was evaluated by elongation testing.<\/p>\n

<\/p>\n

\"Pull-adhesion<\/a>
Pull-adhesion testing using a universal test machine.<\/span><\/figcaption><\/figure>\n

Water absorption<\/i>
\nFrom previous testing of roofing and waterproofing membranes, water absorption has proven to be a good indicator of long-term membrane durability. Currently, no industry standards address water absorption of fluid applied membranes; therefore, traditional water absorption testing of waterproofing and roofing membranes is a starting point. Industry experience has shown reliable waterproofing membranes have low water absorption, ranging from less than a four percent increase by weight to an upper bound of 10 percent.<\/p>\n

While the air barrier will be exposed to far less water than will a roofing or plaza waterproofing membrane, cladding systems are almost never watertight. This means the air barrier, which typically also acts as the WRB, is exposed to some water. Additionally, when insulation is used in the cavity wall, water can be held against the membrane for prolonged periods, trapped between the air barrier and the insulation. Often, water entering cavity walls does so at the same locations during each storm; while the entire wall membrane might not be wetted, other areas will be, repeatedly.<\/p>\n

Summary of conditioning<\/b>
\nTo help assess the prospects for long-term product performance, samples were conditioned to reflect various environmental factors, and the pull-adhesion, elongation, and water-absorption tests were repeated. Conditioning of the samples included exposing them to UV light, freezing temperatures, accelerated aging, and water exposure. Only one conditioning element was applied to an individual sample, and not the aggregate of all the conditioning.<\/p>\n

UV exposure<\/i>
\nUsing a UV fluorescent light apparatus, the samples were exposed to UV light for 14 days\u201422 hours of UV light followed by two hours of condensation daily.<\/p>\n

No direct correlation can be made between hours in the UV machine and days exposed on a job site. Of all conditioning procedures, UV-exposed samples exhibited the greatest change in physical appearance.<\/p>\n

All tested fluid-applied air barrier products, except one, are not marketed as \u2018UV-stable\u2019 and not intended to be exposed (permanently) to UV light. Still, all products will be exposed to UV for some amount of time, depending on the phasing of construction projects.<\/p>\n

During testing, two of the membranes changed color after exposure. Three of the membranes, including the one marketed as \u2018UV-stable,\u2019 exhibited cracking and crazing of the exposed surface.<\/p>\n

\"Elongation<\/a>
Elongation testing using a universal test machine.<\/span><\/figcaption><\/figure>\n

Freezing temperatures<\/i>
\nBefore testing, the samples were exposed to \u20136.7 C (20 F) temperatures for 48 hours, followed by 24 hours minimum at room temperature.<\/p>\n

Accelerated aging<\/i>
\nThe samples were oven-aged for 28 days at a temperature of 70 C (158 F), followed by 24 hours minimum at room temperature prior to testing.<\/p>\n

Water exposure<\/i>
\nFor elongation testing, samples were submerged in distilled water for 24 hours. For adhesion testing, edges of the substrates were taped off to prevent water absorption by the substrate, and the membrane covered with wet burlap and polyethylene for 24 hours. All samples dried for at least 24 hours before testing.<\/p>\n

Testing procedures<\/b>
\nTesting of each respective property was conducted in general conformance with ASTM standards:<\/p>\n

Adhesion to substrate<\/i>
\nUsing ASTM D4541, Standard Test Method for Pull-off <\/i>Strength of Coatings Using Portable Adhesion Testers<\/i>, adhesion of the fluid-applied air barriers was tested to six common construction materials, all of which are listed as acceptable substrates for the nine materials tested. As shown in Figure 3, substrates tested were:<\/p>\n