Summary:  ISO is revising the commercial property Earthquake rules, Rules 73. Causes of Loss – Earthquake Form and Rule 75. Earthquake And Volcanic Eruption Endorsement (Sub-Limit Form). The rules are revised in connection with the new soft story rating factor in the ISO CLM that was recently introduced for commercial property. At the time the soft story factor was implemented it did not apply to earthquake coverage when the building has a soft story. The earthquake rules are now being revised to include a soft story modification factor. The proposed effective date of the revisions is 8/1/23.

Soft Story:

Soft story refers to a particularly weak, flexible or otherwise vulnerable ground floor, most common in older, wood-frame, multi-story buildings. A soft story often features relatively large window and door openings and has fewer partitions (less bracing) than the overlying levels. Examples of structures with a soft story include an apartment building with storefronts on the ground floor or a house with the living space constructed over the garage.

Soft story modification factors will not apply to buildings retrofitted or engineered to mitigate the seismic effects of soft story.