EDUCATION > Did You Know? > General > Wind Zone Requirements

Wind Zone Requirements

atas-wind-zone-requirements-th.jpgThe American Society of Civil Engineers (ASCE) produces a document called ASCE 7 that is used in calculating design loads for buildings, including snow, seismic and structural loads. Building codes reference ASCE 7 when referring to minimum design loads required in a locality. ASCE 7-10 is referenced by IBC 2012 and other building codes. Like building codes, the ASCE 7 document is updated on a cyclical basis. ASCE 7-16 is currently being evaluated, and could result in design load changes when adopted by building codes.

ASCE 7 contains tools and definitions to help in designing allowable loads on buildings:
  • Wind hazard maps define maximum wind speeds.
  • Exposure categories for buildings define the geographic area around a structure. They are determined in part by the roughness category of the terrain.
  • Occupancy categories define the risk for human hazard if the building fails.

Exposure and Occupancy categories are used with wind hazard maps to calculate the design loads for a building, via “importance factors” or design coefficients.

There are five building zones that apply to buildings. Edge and corner zones generally need to be designed to withstand higher loads than the corresponding field zones.
  • Zones 1-3 occur on the roof, and correspond to the field, edges and corners, respectively.
  • Zones 4 and 5 are assigned to walls and correspond to the field and corners of the wall, respectively.

Designers look at wind zone requirements and building zone requirements to determine
  • Clip spacing
  • The type of roof or wall panel that can be used
  • A panel’s material and gauge
  • The type of perimeter edge enhancement necessary for a roof