The Whole Building Design Guide (WBDG) www.wbdg.org is a comprehensive, knowledge-based Web site developed and maintained by the National Institute of Building Sciences (NIBS). The widely accessible, Web-based resource has logged 150,000 monthly users and 600,000 document downloads per month. The publication has rapidly become the primary portal for construction professionals seeking access to design criteria and base-building design principles of critical concern to the Army Corps of Engineers, Naval Engineering Facility Command, U.S. Air Force, and General Services Administration.
A major component of the WBDG is the Envelope Design Guide (EDG), a comprehensive federal guideline for exterior building enclosure design and construction. The EDG is funded and supported by the General Services Administration, Army Corps of Engineers, Naval Facilities Engineering Command, U.S. Air Force, Department of Energy, and Federal Emergency Management Agency.
The EDG was developed by NIBS, in cooperation with Simpson Gumpertz and Heger Inc. (SGH), Wiss, Janney, Elstner Associates Inc. (WJE), Carl Walker Associates Inc., T.L. Smith Consulting, Hinman Consulting Engineers, HKS Inc., and Building Systems Development Inc. The Envelope Design Guide is available to the public through the WBDG and online at www.wbdg.org/design/envelope.php.
The EDG is a technically-sound, peer-reviewed body of knowledge that offers valuable insight to both design and construction professionals regarding a wide range of principles considered critical to construct a properly functioning, weather-tight building enclosure. The ultimate goal of the EDG is to provide a readily accessible set of building enclosure design and construction guidelines for use in the development of federally-owned and operated office buildings and institutional facilities.
Six major chapters are included in the Guide:
- Introduction by Building Systems Development Inc.
- Below Grade Systems by Carl Walker Associates Inc.
- Wall Systems by WJE
- Fenestration Systems by SGH
- Roof Systems by T.L. Smith Consulting
- Atria Systems by HKS Inc.
The EDG also includes resource pages that expand upon the basic design principles summarized in each chapter, covering issues such as blast protection, indoor air quality and mold, sustainability, and flooding. Although the original intent of the Guide was for use by the federal government and contractors and designers working for the government, it became a valuable technical resource for designers, contractors, builders, architects, engineers, and material suppliers in both the public and private sectors.
This article concentrates on two of the chapters – Wall Systems and Fenestration Systems – of particular interest to the stone and masonry industry.
The introduction sections for each of the major above- and below-grade building enclosure chapters present an overview of technology principles specific to the section. The wall chapter introduction provides building science theory related to the physics of heat, air, and moisture transfer through the building enclosure, together with a glossary of key terms and definitions necessary to understand the principles.
Tables in the introduction and referenced in each of the different wall type subchapters deliver guidance on climate specific design with respect to considerations for the air barrier system, location of the thermal barrier, and evaluation of whether or not a vapor retarder may be needed to control diffusive vapor transfer.
These concepts are further expanded in each of the wall subchapters to include specific guidance regarding the proper management of bulk rainwater penetration, condensation, moisture-laden airflow, and diffusive vapor drive through the building enclosure. They are conveyed graphically through a series of two- and three-dimensional, step-by-step architectural details. These details illustrate how base-building concepts conveyed in the EDG can be applied during the design and construction process. (Figure 1 and Figure 2 show two of the masonry wall details; click on the images to make them larger)