Vapor Permeable or Impermeable Building Envelope Materials, Does It Matter?
The building envelope (or enclosure) is the part of the building that physically separates an interior conditioned space from the exterior environment. Its role has evolved from basic protection to providing a well-controlled and comfortable indoor space and consists of many components that must work together.
Unfortunately there are often unintended consequences that are not always understood when a material performs functions beyond its primary intended uses. This article describes the potential consequences of unintentional vapor barriers and why vapor permeance of building envelope layers is relevant to moisture management and long term durability.