Water-Vapor Transmission in Building Envelopes
A proposed ASTM International standard will help engineers to better understand how various climates affect water vapor transmission of water-resistive barriers and air barriers (WRB/AB) in building envelopes. ASTM’s performance of buildings committee (E06) is developing the proposed standard.
ASTM International member Danko Davidovic says that the proposed standard (WK51917) will explain how WRB/AB function in various wall and roof assemblies.
“The proposed standard is focused on factors affecting WRB/AB performance, best practices to test, and ways to easily report water vapor transmission characteristics,” says Davidovic, senior building scientist, Huber Engineered Woods. “The standard will be easy to follow and reflect the current best building science practices regarding how water vapor transmission properties of WRB/AB impact moisture transport through wall and roof assemblies.”
Davidovic notes the following potential uses for the proposed standard:
- Manufacturers will find the proposed standard to be a resource to educate themselves about real-life performance of WRB/AB products.
- Regulatory agencies will be able to improve water vapor transmission property requirements for WRB/AB materials and systems in current building codes.
- Architects, designers, and engineering professionals will be able to better calibrate the design requirements and specify WRB/AB water vapor transmission properties in their design documents.
- Educators will be able to use the proposed standard as a supplemental educational tool in engineering curriculums for building envelopes, as well as in industry training programs on the best WRB/AB products for a particular project.