Code Interpretation:
These codes imply that all steep-slope and low-slope roof systems shall be designed and installed to meet wind resistance requirements. Wind resistance for roof systems is primarily wind-uplift resistance. Section 1609.0 (referenced in the code) states, “All buildings, other exposed structures, components, cladding and roof coverings shall be designed to resist the pressures caused by wind in any direction as provided for herein.” The provisions and formulations provided in Section 1609.0 are identical to formulations used by ASCE and Factory Mutual. The section provides the required reference material to determine wind-uplift resistance for specific structures. The procedure to determine roof wind uplift classifications on specific buildings during the design phase is based a calculation that takes into account the basic wind speed in the geographical area, ground surrounding the building and the roof uplift pressure at the field of the roof. The buildings height and perimeter construction is also considered. It is the responsibility of the specifier to complete these calculations. It is the specifier’s responsibility to determine the proper wind uplift classification for the building.

The code also states the all applied roof materials shall be tested and approved for use by FM (Factory Mutual) and UL (Underwriters Laboratories). Required FM testing is in accordance with their standard 4450-90 Approval Standard for Class I Insulated Steel Deck Roofs and 4470 – 86 Approval Standard for Class I Roof Coverings. The required UL testing is standard 580 – 94 Test for Uplift Resistance of Roof Assemblies. This provides a departure from conventional thinking that only Factory Mutual Insured properties must meet their wind-uplift and testing standards.