(JBED) - Summer 2006 - The Whole Building Design Guide

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eferences ASTM F2248 Standard Practice for Specifying an Equivalent 3-Second Duration Design Load for Blast Resistant Glazing Fabricated with Laminated Glass, a static design methodology. Except for retrofit applications, fragment retention film is not considered a glazing alternative. This year, the American Architectural Manufacturers Association published AAMA 510-06 Voluntary Guide Specification for Blast Hazard Mitigation for Fenestration Systems (available at www.aamanet.org). The document establishes standard test sizes for fenestration system evaluation and comparison. THE DESIGN PROCESS The design process may be different from project to project. In some cases, an experienced blast consultant will be required to conduct a vulnerability assessment and recommend blast loading requirements in terms of pressure and impulse, as well as the acceptable level of performance for the fenestration system. Blast consultants often design programs to test proposed systems—at laboratories with shock tubes or in an open-air arena setting. The U.S. State Department now has three standard designs for small, medium and large embassy projects that are constructed on a design-build basis. Blast resistant exteriors are part of the master plan for the security of these buildings. Fenestration design for embassies has been addressed by U.S. State Department standards, which call for a higher level of performance than other blast resistant window and curtain wall systems. Special attention has been given to attachments and frame details of these systems. One such system incorporates vertical and horizontal tubes or muntins that support the laminated glass in the window. The system is designed to transfer the load from the glazing to the structural muntins and frame and ultimately to the adjacent structure (Valerie Block and David Rinehart, “Security for U.S. Embassies,” Glass, June 2004, pp 67-68). TRENDS FOR THE FUTURE As terrorist threats increase, the concern for building protection is expanding from government buildings—courthouses, military housing, and embassies—to commercial building projects. Because building codes in the United States represent minimum standards of construction, it is unlikely that mandatory requirements for security will be established any time soon for commercial construction. As a voluntary solution, building owners and insurance companies may be the pivotal force in driving the adoption of security glass solutions. It is clear that designers are placing a greater importance on the combined benefits of hurricane and seismic resistance, bomb blast and forced entry protection, and better acoustical and energy performance. Laminated glass installed in a properly designed fenestration system can deliver all of these benefits, but most importantly, it can protect people inside and outside of buildings from glass-related injuries and the buildings themselves from catastrophic collapse and damage. ■ Valerie Block is a Senior Marketing Specialist with DuPont Building Innovations, Wilmington, DE. Tammy Amos is a Marketing Specialist with DuPont Glass Laminating Solutions, Wilmington, DE. 40 Journal of Building Enclosure Design
Feature How Does Fenestration Fit In Where have we been, where are we now and where are we going By Barry G. Hardman, National Building Science Corporation; James D. Katsaros, Ph. D., E. I. Dupont de Nemours and Company A SIMPLE PURPOSE Fenestration has one primary purpose and that is to hold glass. This article first reviews glass, then sash (that holds the glass in the window frame), then problems with today’s fenestration installations, and finally a new forward-looking concept currently under development— an installation process that utilizes gravitywater management principles. Glass has been an important building material for millennia and, until 1960, glass had very few changes. When the Pilkington brothers invented the float process for glass manufacture, it opened up the doors to a plethora of new and exciting glass products. Through 1960, glass was a fairly basic material, which came in just a few colors (clear, grey and bronze), which could be made obscure by rolling a pattern on it while it was still hot. RECENT INNOVATIONS IN GLASS In the past 40 years, glass manufacturing has become an extremely sophisticated industry that has developed glass that can be used for energy savings, safety, sound control, impact and blast resistance, photovoltaics, privacy (switchable New glazings with spectrally selective low-E coatings can reduce solar heat gain significantly with a minimal loss of visible light (compared to older tints and films). glass) and the list goes on. In the not too distant future, electrochromic glazing will contribute further energy optimization in commercial buildings. WINDOW FRAMES, SASH AND INSTALLATION INSTRUCTIONS At the turn of the last century craftsmen, carpenters and builders would build their walls in such a manner as to include the window frame. The craftsmen used common wooden mill stock which was designated by part numbers in the architect’s and mills’ catalogs, to integrate window sills, jambs and head frames into the building. They used proven water management details, such as slopes, shiplapping and drip chamfers. Architectural detail books often gave examples of good vs. faulty methods of integrating the frames (using the mill stock) into the wall. Window sills, for example, always ran well beyond the jambs and were sloped, allowing water to freely run off and be delivered to the outside of the cladding. The tops of window frames were also integrated with the cladding in a shiplap fashion that guaranteed water was drained to the exterior, using gravity. Sealants were not available, thus frame integration into the wall relied on known physics—simply stated, water likes to run downhill. SASH WAS INSTALLED LATER INTO THE WINDOW FRAME Around 1910, mill companies, which also provided the mill stock to the craftsman, usually manufactured sashes (the framework portion of the window that holds the glass), which could be either glazed or unglazed, and they were sold separately to the builder to install into the previously integrated window frame that was part of the wall. Everybody used the same sizes, mill stock and methods, therefore windows were uniform throughout the industry, and sizing was based on available glass, which was sold by even twoinch increments. PREASSEMBLED WINDOW UNITS—LOST INSTALLATION PRINCIPLES Early in the twentieth century, the United States was well into the Industrial Revolution and one of the innovations from that entrepreneurial time was the prefabrication of the window frame and the sash as a whole unit. Thus, the window as we know it today was born. Unfortunately, with that came the uncertainties of installing these pre-manufactured assemblies into the wall correctly with procedures that allow for good water management. WINDOW AND INTERFACE LEAKAGE DOCUMENTED Most windows eventually leak. In particular, the window-wall interface often leaks. That is why there was a need for a national consensus installation standard. Examine the abstracts for patents filed on window systems over the last couple ofcenturies—they attempt to address an ongoing problem—window leakage into the wall cavity. Summer 2006 41
Page 1: JBED Summer 2006 Journal of Buildin
Page 6: Message from NIBS David A. Harris,
Page 10 and 11: Feature Dynamic, Integrated Façade
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Page 14 and 15: procure them for the final building
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Page 19 and 20: Feature All That Glass Is there an
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Page 26 and 27: Feature Architectural Glazing for S
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Page 30: esidents. Another concern from the
Page 33 and 34: from the California Central Valley
Page 37 and 38: Feature Window Comfort & Energy Cod
Page 39: By Valerie L. Block and Tammy Amos,
Page 43: Council (ICC), one might expect tha
Page 46 and 47: Industry Update By James C. Benney,
Page 48 and 49: BEC Corner HOUSTON-BEC By Andy MacP
Page 50: Buyer’s Guide AIR BARRIERS Dupont

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