RCW 70.86.030
Standards for design and construction.
Structural frames, exterior walls, and all appendages of the buildings described in RCW 70.86.020, whose collapse will endanger life and property shall be designed and constructed to withstand horizontal forces from any direction of not less than the following fractions of the weight of the structure and its parts acting at the centers of gravity:
Western Washington 0.05.
[ 1955 c 278 ยง 3.]
Structure Revised Code of Washington