Making Transitions: Keeping Air and Water Barriers Continuous

Building envelopes need to create the four barriers needed as part of any building enclosure, namely water-resistive barriers (WRBs), air barriers (ABs), thermal barriers, and vapor retarders. Commonly, those are each thought of as independent products or systems that are easy to imagine across a smooth continuous plane in a wall or roof deck. However, actual construction isn’t completely smooth and continuous. There are places where different materials and assemblies meet, such as the transition from an above-grade wall to a concrete slab or foundation wall. There are also openings in most walls for windows, doors, and other features, meaning there is a transition of the barriers around those openings. The place where the roof meets the wall, particularly in a commercial building that may have a parapet wall, is another transition area where the continuity of the barriers can be compromised if they are not designed, detailed, and installed correctly. In this course, we will focus on these three transition areas in particular: wall to foundation, openings, and roof to wall. Further, recognizing the innovations and risk mitigation needed in building envelope design, we will also look at the latest advances in all-in-one, integrated gypsum sheathing that include WRB and AB systems during manufacturing as alternatives to field-applied water- and air-barrier systems. These integrated systems have been shown to reduce improper field installations, speed up installation, and save time and money during construction. As such, greater reliability and less risk have been found in using such integrated solutions compared to separate field-applied solutions.

Learning Objectives

  1. Identify the role that building construction transitions play (roof to wall, wall to foundation, and wall to disparate materials) in achieving a well-designed building envelope, including conditions that contribute to failure.
  2. Recognize the points in the design process where construction transitions need to be addressed and specific areas that required detailed attention.
  3. Review the conditions that promote movement of bulk water, moisture, or vapor drive and how those conditions impact construction transitions, specifically at roof-to-wall, wall-to-foundation, and wall-to-disparate-material locations.
  4. Describe the importance of maintaining the continuity of water-resistive barriers and air barriers across construction transitions, and assess integrated sheathing products and systems as a means to achieve that continuity.

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