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Soft-Story Seismic Evaluations

Berkeley, CA
Interactive Resources' structural engineers can assist owners of soft-story buildings navigate their way through local ordinances and provide compliance quickly and cost effectively. They have a comprehensive knowledge of the specific safety requirements of the Bay Area and the communities within the region. Soft-story engineering services include soft-story building evaluations, seismic analysis and retrofitting, structural construction documents and calculations, and construction administration services.

Soft-story buildings covered by these ordinances are typically multi-story apartment or condominium buildings built before as late as 1991 that have garages, carports or commercial spaces on the first floor. The lack of walls at the first story makes these building vulnerable to serious earthquake damage.

During the 1989 Loma Prieta earthquake, soft-story collapses killed 63 people and left 7,700 housing units uninhabitable. In the 1994 Northridge earthquake, soft-story apartment and condo buildings collapses killed 16 people and were responsible for about two-thirds of the 46,000 uninhabitable housing units in the Northridge earthquake.

In 2005, AB 304 (now California Health and Safety Code Sections 19160 et seq.) allowed local jurisdictions to identify soft-story residential buildings that are potentially hazardous to life in the event of an earthquake and establish local standards for retrofitting them. Cities have taken varying approaches.
  • Oakland has a voluntary soft-story seismic strengthening program. The City of Oakland is now offering two new seismic grant programs — the Safer Housing for Oakland Program (SHOP) and the Earthquake-Safe Homes Program (ESHP). > more information
  • San Francisco's seven-year program started in September 2013. The program is divided into three phases. > more information
  • Alameda requires mandatory evaluation of soft-story buildings constructed prior to December 17, 1985, not later than 18 months following notice by the city.
  • Fremont requires evaluation of soft-story buildings constructed prior to January 1, 1978. Compliance is voluntary except for apartment houses, which must be upgraded within four to five years, depending on the number of units.

Representative Projects


Soft-Story Evaluation and Retrofit - Shadowbrook Apartments; Sunnyvale,CA
Soft-Story Evaluation & Upgrade - Heatherstone Apartments; Mountain View,CA
Soft-Story Evaluation & Upgrade - Apartments; Alameda,CA
Soft-Story - Seismic Evaluations; Berkeley,CA
Seismic Analysis & Retrofit - Cambria Apartments; Sunnyvale,CA
Sequoia Apartments - Seismic Upgrade; Redwood City,CA
Seismic Retrofit & Emergency Repairs - Mirasol Condominiums; San Francisco,CA