StoGuard Proves Why ASTM E 2357 is the Bellwether of Air Barrier Testing

Proven Performance in Lab and Field testing

ATLANTA - StoGuard, the waterproof air barrier, has recently passed the ASTM E 2357 testing that proves the performance of this fluid-applier air barrier that some are referring to as "spray-on energy efficiency."

StoGuard, manufactured by Atlanta based Sto Corp., was introduced into the market in 2001 and has been gaining ground with real world and lab testing showing its efficacy in the field. However, what exactly is the ASTM E 2357 and why should architects, specifiers, and contractors care about it?

"This test method is intended to simulate the performance of various air barrier materials/accessories when combined into an assembly, said Lisa Petsko, StoGuard product manager. "Based upon the results of the measurements, this procedure then assigns an air leakage rating for the air barrier assembly."

She went on to explain that architects, specifiers, and contractors should not only be aware of this test, but to incorporate only those that have passed this test. Other considerations include the material cost and installation time and ease when selecting an air barrier. StoGuard incorporates ease of installation and cost-effectiveness in a high performance product.

Officially known as ASTM E 2357, Test Method for Determining Air Leakage of Air Barrier Assemblies, test specimens are 8-ft by 8-ft (2400 x 2400 mm) and include a panel with a rough opening (filled with a plywood blank), circular pipe penetration, HVAC duct penetration, electrical box attachments and penetrations, and brick ties. This "detail" panel also includes transition details to adjacent framing and a concrete foundation or slab.

According testing sources, the ASTM E 2357 includes a multi-step loading protocol, which subjects the assembly to both negative and positive pressures for sustained periods and repeated cycles of rapid loading followed by positive and negative gust loading.

After completion of the loading protocol, a final air leakage rate is measured and reported. The maximum allowable air leakage rate required by most codes for air barrier assemblies is 10 times more than for an air barrier material, or 0.2 L/som².

Many products meet the definition of an air barrier material. Gypsum sheathing products are the baseline materials meeting the air leakage requirement: <0.02 L/s.m² (<0.004 cfm/ft²). The treatment of joints between sheathing boards and the sheathing fasteners will essentially define the air barrier performance of a gypsum sheathed, framed wall assembly. Sto Corp. performed the ASTM E 2357 test with StoGuard materials used only on the joints, sheathing fasteners, and transition details.

The air leakage rates obtained by Sto Corp. in this test are conservative values and represent the maximum air leakage that can be expected for a properly installed StoGuard system because the field of the sheathing was left untreated.

Added resistance to air leakage and water resistance can be obtained by applying StoGuard coatings (Sto Gold Coat, Sto EmeraldCoat, or StoGuard Vapor Seal) to the surface of the sheathing. Each of the coating products meets the requirements of an air barrier material on their own when tested in accordance with ASTM E 2178.

About Sto Corp.

Sto Corp., based in Atlanta, Georgia, is an innovative leader and producer of a broad range of versatile cladding and coating systems for building construction, maintenance and restoration. Sto Corp. is ISO 14001:2004 (environmental management) as well as ISO 9001:2008 certified and operates production plants strategically located to serve more than 200 distributor shipping locations across North and South America. At research and development laboratories in the U.S. and Europe, Sto continues to revolutionize the industry with the highest quality products and application technology. Sto is also the world's largest manufacturer of exterior thermal insulation systems with 27 subsidiaries operating at 21 factories worldwide.

For more information, visit or call toll free (800) 221-2397 or (404) 346-0755. Follow Sto Corp. on Twitter as well as the Sto blog "Building with conscience" at

For more information contact:
Michael Sweeney, LEED Green Associate,
Sto Corp.,

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