May 4, 2016
New versions of wood and gypsum sheathing panel products with surface treatments to comply with building code requirements for water-resistive barriers (WRB) and air barriers (AB) are now being marketed. The WRB/AB performance of the sheathing products is generally provided by either application of a coating or facing to the exterior surface of the panel or treatment of the core during manufacturing. The method and materials used by each sheathing manufacturer is unique to the brand of the sheathing.
Specifiers and contractors who seek to use these products as substrates for exterior insulation and finish systems (EIFS) must consider the following:
- Verification that the specified assembly (including sheathing) complies with all applicable building code requirements, including NFPA 285 compliance, is the responsibility of the design professional.
- Building Code compliance recognition of EIFS systems is based on system testing over specific substrate materials. If the specific sheathing product has not been tested, properties which depend in some part on the sheathing or adhesion to the sheathing must be verified to comply with ASTM E 2568, Standard Specification for PB Exterior Insulation and Finish Systems, and to meet code and project requirements.
- EIF systems applied to the WRB/AB sheathing products require drainage testing in accordance with ASTM E2273, Standard Test Method for Determining the Drainage Efficiency of Exterior Insulation and Finish Systems (EIFS) Clad Wall Assemblies. The drainage efficiency of the assembly will depend, in-part, on the surface characteristics of the substrate. Therefore EIFS applied to a WRB/AB faced sheathing cannot be considered “EIFS with Drainage” unless the testing is performed. The use of EIFS without drainage may require additional special inspections during construction to comply with the applicable building code.
- Although the sheathing may be recognized and function as an air/water resistive barrier material, the sheathing joints and sheathing fasteners must be sealed with an air/water resistive barrier material which may or may not be supplied by the sheathing manufacturer. Verification of compliance of the sheathing joint materials with applicable code requirements may also be required.
Each individual EIFS manufacturer will determine company-specific positions with regard to topics such as warranties; consent to share proprietary test data; and marketing/sales efforts in regard to the use of WRB/AB sheathing materials as substrates for use with their branded EIFS.