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Designing the Right Fit Intersections between moisture barrier systems are often where failures occur b y A n d y M a c P h i l l i m y , AIA
In my 30-plus years as an architect I have seen few moisture intrusion problems that were the result of product system failures. More frequently, failures occurred at the intersections and transition details between moisture barrier systems. Such failures were caused by a variety of issues, including trade craftsmanship, system product incompatibility, or failure in the “joint” design. This article will first establish an approach for proper design for applying moisture barriers and the related joints between moisture barrier systems. Second, it will examine the range of factors critical to the design of the associated joint details. Last, it will look at best practices during the construction phase that ensure these details are properly constructed.
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Design Approach for Moisture Control In his article “Protecting Against Moisture” in the September/October 2006 Texas Architect, Joseph L. (Chris) Crissinger identified four methods of moisture movement through building enclosures: (moisture-laden) air, capillary action, liquid flow (water), and vapor diffusion. Of these, this article focuses on the protection against moisture intrusion as water and air. The complex issues of vapor diffusion control and the use of vapor barriers/retarders are well discussed in the article “Use of Air Barriers and Vapor Retarders in Buildings” by Charles W. Graham, PhD, AIA, in Texas Architect September/October 2004. However, many of the design factors and need for continuity are similar between air and vapor barriers.
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Texas Architect is the official publication of the Texas Society of Architects, each edition features recently completed projects and other...