San Francisco Building Inspection Commission Codes § 10.1 Code-Based Site Classification

The Site Class designation should be made following the current edition of the applicable code and standard (e.g., ASCE 7, SFBC). The Site Class definitions should be based on Vs30 and presence of soft clay or liquefiable soils. According to the code-based Site Class designation, Vs30 is defined in the free field from the ground surface to the

depth of 30 m (100 ft). However, Site Class may be defined below the bottom of the mat foundation (see Section 10.2.2 Ground Motion Characterization Commentary), if deemed appropriate.