Seismic Design Category Maps for Residential Construction in Washington

These  maps were developed by the Washington State Department of Natural Resources, Division of Geology and Earth Sciences under the supervision of Ron Tessere. Ron is the State Geologist. The maps are based on ICC maps with known local geology incorporated. They take a while to download even on a fast connection. 

The maps are intended as a guide for the local building official and are not intended to take the place of site specific soil investigations. Each site should be evaluated for consistency with these maps. Local conditions such as steep slopes, highly liquefiable soils, poor soil bearing or expansive soils must be evaluated on a site by site basis. The sole purpose of these maps is to provide a basis to assign a residential Seismic Design Category.

The updated IRC seismic design maps can be found by clicking on the links below:

http://www.wabo.org/2006_IRC_Seismic_Maps/irc_map_plate1.pdf

http://www.wabo.org/2006_IRC_Seismic_Maps/irc_map_plate2.pdf