Code Compliance

United States
Model building codes and state and municipal codes in the United States do not address air barriers, moisture barriers and vapor retarders in a uniform way. Energy codes in the United States, including the IECC (International Energy Conservation Code), the State of Massachusetts Building Code, and ASHRAE's 1999 energy conservation standard (ANSI/ASHRAE/IESNA Standard 90.1-1999, Energy Standard for Buildings Except Low-Rise Residential Buildings, an energy conservation standard which is required to be adopted by state building energy codes under the Federal Energy Conservation and Production Act) require air tightening of the building envelope. Although codes in the United States do not always provide specific limits for air leakage of air barrier materials, the generally accepted limit is 0.02 L/(s·m2) at 75 Pa pressure [0.004 cfm/ft2) at 1.57 psf)] based on National Building Code of Canada requirements.

Most model codes generally require the use of a water-resistive barrier in wall construction and prescribe asphalt saturated felt (IBC Chapter 14, paragraph 1404.2). They often require the use of vapor retarders in wall construction (IBC Chapter 14, paragraph 1403.3) unless other means are provided to avoid condensation.

Fluid applied air/moisture barriers are proprietary materials and are not listed in model codes. Provisions are made for non-traditional building materials like building wraps and fluid applied air/moisture barriers as an "alternate material, design or method of construction."2 Approval by the building official is based on his/her finding that "….the intent of the provisions of the code [are met]…and that it [the air/moisture barrier material] is at least equivalent in quality, strength, effectiveness, fire resistance, durability and safety to the materials or methods of construction listed in the code."3 In practice the building official cannot evaluate each and every new material or method of construction, so model code evaluation agencies do this for him/her and publish evaluation reports which describe the use and limitations of alternate materials. Therefore it is always important to verify compliance of a fluid applied air/moisture barrier material with the code via an evaluation report.

Southern Building Code Congress Public Safety Testing and Evaluation Services, Inc. publishes an Evaluation Guide on Floor, Wall, and Roof Systems (Testing for Moisture Protection Barriers-SBCCI PST & ESI Evaluation Guide 119), which lists specific performance criteria for air and moisture barriers, including fluid applied air/moisture barriers. Conformance with these criteria is the basis for code recognition of fluid applied air/moisture barriers. ICBO ES (International Conference of Building Officials, Inc.)

is similarly in the process of developing a criteria for water-resistive coatings that function as alternates to UBC (Uniform Building Code) prescribed weather-resistive barriers.