General Snow Load Guidance
Section 1608 of the International Building Code provides a roof snow load chart and table for the United States. The first paragraph of 1608.1 dictates the general calculation of live loads. The referenced Section 1607 refers to the calculation of live loads and enumerates different types of loads that meet live load criteria (live, uniform, vehicular, helipad, etc.).
1608.1 General. Design snow loads shall be determined in accordance with Chapter 7 of ASCE 7, but the design snow load shall be not less than determined by Section 1607.
United States – Graphical and Tabular Snow Loads
1608.2 provides specfic snow loading via Figure 1608.2 (contiguous U.S.) and Table 1608.2 (Alaksa). Figure 1608.2 is a graphical map that presents snow loads in feet based on the area. The roof snow load chart ranges from 0 feet in the southeastern United States to 6800 feet in mountainous regions.
Table 1608.2 provides a roof snow load table for Alaska.
1608.2 further details snow load applicability to design loading.
1608.2 Ground snow loads. The ground snow loads to be used in determining the design snow loads for roofs shall be determined in accordance with ASCE 7 or Figure 1608.2 for the contiguous United States and Table 1608.2 for Alaska. Site-specific case studies shall be made in areas designed “CS” in Figure 1608.2. Ground snow loads for sites at elevations above the limits indicated in Figure 1608.2 and for all sites within the CS areas shall be approved. Ground snow load determination for such sites shall be based on an extreme value statistical analysis of data available in the vicinity using a value with a 2-percent annual probability of being exceeded (50-year mean recurrence interval). Snow loads are zero for Hawaii, except in mountainous regions as approved by the building official.