Fluid-applied ba rriers Gom bat mo I d

BylisaPe,sk.

Product Manager-Sto Guard Sto Corp. Atlanta, Ga.

\Igenerally cons

gate or eliminate one of the USE OF a lluid-applied structural moisture banie minimizes the Construction detailing is a major forces that causes water risk of damage frohi water intrusion during or after construction. critical component for the sucinfiltration into walls: pressure photobystocorp. cess of any wall assembly. difference. A waterproofing/air Aside from minimizing and barrier, in combination with venting controlling the condensation that may and compartmenting, enables the because of air leakage and condensa- occur via air leakage or water vapor pressure behind the cladding material tion-mold growth, decay, corrosion, diffusion, the designer must also creto equalize with the pressure outside, loss of insulation value, degraded ate construction details that prevent and prevent rainwater penetration Indoor Air Quality-are minimized. rainwaterpenetration. caused by pressure differentials. Controlling moisture helps to control Fluid-applied waterproofinglair

By designing and constructing an mold growth in wall assemblies. barriers can effectively resist water airtight building envelope, the risk of Air leakage has proven to be a sig- penetration for up to 75 minutes when moisture problems that can occur nificant potential source of condensa- subjected to water spray equivalent to tion and moisture accumulation in 8 inches (203 mm) of rainfall per hour building envelope assemblies, accord- driven by an approximate 50 mile-

Ftuid-Apptied Air Barriers ;::":".il:'1'Jl3juJ#J*#l ffi1::i"Xlf;Jn:'j#*,ff?i'tr include

moisture contributed by air leakage E-331, also has the ability to allow Eanleffi|tomCartideCoatings versus vapor diffusion over a period water vapor to pass through yet keeps of one year. The results: infiltration/ damaging moisture from penetrating exfiltration proved to be a significant the sheathing. potential source of moisture accumu- The traditional choice for moisture lation in walls and/or high relative protection has been asphalt saturated humidity levels in interior spaces. felt paper, which could tear or be mis-

Water vapor diffusion, on the other lapped during construction. These hand, was shown to be a much less choices also need to be covered significant potential source of mois- quickly, whereas a fluid-applied air turethanoncethought. and moisture barrier may be left

At the same time, airtight construc- uncovered during the construction tion is likely to be less capable of dry- process. Traditional housewraps and ing than "air-porous" construction in building papers, depending on brand the event of water leakage or other or type, measure water resistance in unforeseen circumstances that cause hours. and in some cases. allow water water to enter a wall assembly. The penetration within the first few mindesigner then must strive to prevent utes of exposure.