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This guideline from the Institute for Business and Home Safety (IBHS) is intended to provide a set of specifications that is more consistent with the International Building Code (IBC) and ASCE 7 wind loads, wind speed maps, and conventions. This effort was prepared as a rapid response to Hurricane Katrina in 2005 to facilitate reconstruction efforts. Consequently, conversions have been prepared based on general relationships. The wind loads in the late 1990's editions of the Standard Building Code are reasonably consistent with ASCE 7 design loads for building located in suburban or forested terrain. This guideline uses nominal adjustments of wind speeds and wind loads from the Standard Building Code to ASCE 7 in accordance to Section 1609.3.1 of the International Building Code.
From the Preface
Most regions in the United States face windstorm threats. Hurricanes strike the Gulf and Atlantic coastal states on the average of one or more times per year, with a single storm capable of producing billions of dollars in damage. An average of 900 tornadoes is reported in the United States annually. Currently, the average wind damage to constructed facilities exceeds $3 billion yearly and is rising with accelerated coastal development and the migration of people to the hurricane prone coastlines. In 2004 and 2005 wind related damage has exceeded $10 to $15 billion each year. Much of this damage can be attributed to the inadequate resistance of non-engineered buildings to high winds.
In 1983, two of the world's prominent wind researchers, GR Walker (Australia) and KJ Eaton (United Kingdom) expressed their frustration concerning the inadequate performance of residential construction on a global scale:
"Basically, society has considered that housing does not warrant engineering analysis and design."
If property damage is to be mitigated in the high wind regions of this country, increased engineering attention must be given to residential construction. During the 1990s and the first half of the 2000s, material associations, including wood, masonry and steel together with academics, product producers, engineers and code officials were engaged in developing guidelines and standards that applied engineering knowledge and analysis to housing. The International Code Council legacy standard SSTD 10-99 and its predecessors were the first US standards for high wind construction of residential structures. The ICC SSTD 10 document was based on the Standard Building Code wind loads and are based on fastest-mile wind speeds. The SSTD 10 standard was well-received by builders and building officials in many parts of the country.
In 2001, both wood and steel associations published construction manuals and standards, respectively, that deal with high wind design with their materials. These are based on the ASCE 7 Wind Loads that are now the basis for defining wind loads in the International Building Code (IBC) and the International Residential Code (IRC).
It is the express purpose of this updated document to provide builders and code officials with simplified guidelines for design and construction details that will improve the structural performance of single and multifamily dwellings. The prescriptive requirements contained herein are based on the latest engineering knowledge and are intended to provide minimum requirements to ensure structural integrity and improve building envelope performance within the limitations in building geometry, materials and wind climate specified. Historically, builders and code officials have found the format of these guidelines to be relatively easy to use and understand. The 1999 edition of SSTD 10, although dated, is referenced by the IBC and IRC and is still recognized as an acceptable alternative to an engineered design for single and multifamily dwelling construction in many jurisdictions.
These revised guidelines have been disseminated to a number of experts for review and comment. However, the development of the revisions has not followed a consensus process and these guidelines are not a consensus document. The primary focus of the effort has been to provide a more contemporary set of prescriptive guidelines while minimizing conflicts with other consensus documents that are currently recognized within the IBC and IRC family of codes. Specifically, the AF&PA Wood Frame Construction Manual (WFCM) is a consensus document that provides design guidance for wood frame buildings, is applicable to a much broader range of building sizes, shapes, exposures and design wind speeds, and is specifically based on ASCE 7 wind loads. Consequently, differences could occur between these guidelines and the WFCM. These differences are most likely the result of different assumptions and simplifications employed for the specific design methodologies. Because of the assumptions used to create the provisions, the user is cautioned to not pick and choose from these guidelines and the WFCM. If the WFCM is used for the design, it should be used for all aspects of the design.
Contents
Chapter 1: General Requirements. General. Design Parameters. Definitions. Design Criteria. Nonrectangular Buildings. Chapter 2: Buildings with Concrete or Masonry Exterior Walls. Scope. General. Footings and Foundations. Floor Systems. Concrete or Masonry Wall Systems. Insulated Concrete Form (ICF) Walls. Attic Floor or Ceiling Systems. Roof Systems. Open Structures. Exterior Wall Veneers. Chapter 3: Buildings with Wood-Framed Exterior Walls. Scope. General. Footings and Foundations. Floor Systems. Wood-Framed Wall Systems. Ceiling Systems. Room Systems. Open Structures. Exterior Wall Veneers. Chapter 4: Combined Concrete, Masonry, or ICF and Wood Exterior Wall Construction. Scope. Concrete, Masonry, or ICF First Story, Wood Frame Second Story. Wood Frame Gable Endwalls above Concrete, Masonry or ICF Walls. Chapter 5: Roof Coverings. Asphalt Shingles. Concrete Roof Tiles. Chapter 6: Windows and Doors. Scope. Windows, Doors and Unit Skylights Installed in Wall/Roof Systems. Protection of Glazed Openings. Appendices. |
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