ASHRAE 189.1, "Standard for the Design of High-Performance,
Green Buildings Except Low-Rise Residential Buildings," provides
guidelines for the use and design of air barriers in roof
assemblies. If you are involved with the design of low-slope roof
systems, you should know how air barriers function and how they are
designed.
Air barriers are used as building envelope components to
minimize the amount of air intrusion and air leakage into and out
of buildings and building envelope components.
Air barriers and vapor retarders play similar but not identical
roles in buildings. Vapor retarders are intended to restrict the
passage of water vapor through materials, and air barriers are
intended to restrict the passage of air flow...
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