47.5 MB - The Whole Building Design Guide

3.1.4 Building CodesThe IBC is the most extensively used model code. However, insome jurisdictions NFPA 5000 may be used. In other jurisdictions,one of the earlier model building codes, or a specially writtenState or local building code, may be used. The specific scope and/or effectiveness and limitations of these other building codes willbe somewhat different than those of the IBC. It is incumbentupon the design professionals to be aware of the specific code (includingthe edition of the code and local amendments) that hasbeen adopted by the authority having jurisdiction over the locationof the critical facility.3.1.4.1 Scope of Building CodesWith respect to wind performance, the scope of the modelbuilding codes has greatly expanded since the mid-1980s. Some ofthe most significant improvements are discussed below.Recognition of increased uplift loads at the roof perimeter and corners:Prior to the 1982 edition of the Standard Building Code (SBC),Uniform Building Code (UBC), and the 1987 edition of the NationalBuilding Code (NBC), these model codes did not accountfor the increased uplift at the roof perimeter and corners. Therefore,critical facilities designed in accordance with earlier editionsof these codes are very susceptible to blow-off of the roof deckand/or roof covering.Adoption of ASCE 7 for design wind loads: Although the SBC, UBC,and NBC permitted use of ASCE 7, the 2000 edition of the IBCwas the first model code to require ASCE 7 for determiningwind design loads. ASCE 7 has been more reflective of the currentstate of the knowledge than the earlier model codes, anduse of this procedure typically has resulted in higher designloads.Roof coverings: Several performance and prescriptive requirementspertaining to wind resistance of roof coverings have beenincorporated into the model codes. The majority of these additionalprovisions were added after Hurricanes Hugo (1989) andAndrew (1992). Poor performance of roof coverings was wide-3-18 MAKING CRITICAL FACILITIES SAFE FROM High Wind