The Four Barriers - Concepts for proper wall design and construction

August 30, 2006
Publication: Construction Specifier v 59 n 8 p 36-42

Contemporary building enclosures generally consist of layers of light-weight construction materials designed to prevent water penetration and control condensation, heat flow, and vapor flow. These layers are material assemblies that serve as four essential barriers – i.e., to resist water, heat, air, and vapor.

The performance of a contemporary building enclosure depends on the proper sequencing, detailing, and constructing of these four barriers.  Barriers must also incorporate design features that enable concealed building materials to dry out and recover from occasional moisture exposure without deterioration or microbial contamination. 

Large building portfolios, such as those managed by hospitals, colleges and universities, and state and local government organizations, often include structures that range widely in age, design, use, materials, and significance. With the complex combination of these variables, it can be overwhelming to confirm that all buildings have properly operating barriers in place to protect them.

This article outlines some of the characteristics and design considerations for each of the four barriers, and  describes their proper integration with each other to create an effective building enclosure.