When the American Society of Civil Engineers (ASCE) first published ASCE 7, "Minimum Design Loads for Buildings and Other Structures," in 1988 (it previously had been published by the American National Standards Institute as A58.1), few people in the construction industry were familiar with the standard. However, during the past several years, the standard increasingly has been used to determine design wind loads, in part because the International Building Code (IBC) began requiring the standard's use in its 2000 edition.
ASCE 7's 2005 edition (ASCE 7-05)—the most current edition—is referenced in the International Building Code, 2006 Edition. The next edition of ASCE 7 is scheduled to be released in 2010.
ASCE 7-05 includes some changes and additions from its 2002 edition that affect the calculation of wind loads on roof assemblies and rooftop equipment. Unfortunately, the document does not clearly note what changes have been made, and determining the changes is a laborious process. I have tracked the changes, and following is an overview of those changes pertaining to calculating wind loads on roof assemblies and rooftop equipment.
Additions and changes pertaining to primary structural elements, such as beams, columns, shear walls and diaphragms that provide support and stability for buildings, are not addressed in this article.