Soft Story Seismic Retrofits


This “soft story” building in San Francisco’s Marina District partially collapsed in the 1989 Loma Prieta earthquake. Open ground level spaces, lacking enough walls, do not have the shear strength to withstand earthquake forces.


Northridge Earthquake, 1994. At first glance this building seems to have suffered little damage, but look closer. Its ground level carport completely collapsed.

Need Caption

Northridge Earthquake, 1994. Similar to the photo above, this building completely collapsed onto its open carport. Many of the casualties resulting from this earthquake occurred in ground level apartments that were crushed due to soft story conditions.

We’d all like to believe that we don’t need to worry about earthquakes. But the reality is, there’s better than a 99% chance of a 6.7 or greater earthquake in California in the next 30 years.*

An earthquake of that magnitude will render hundreds of thousands of Bay Area housing units uninhabitable. Nearly two-thirds of these units will be in “soft story” buildings. That’s why the cities of San Francisco and Berkeley now mandate that such buildings be seismically retrofitted, and the city of Oakland will soon follow. It’s likely that other Bay Area cities that presently require only retrofit design will also soon require that “soft story” retrofits actually be implemented.

“Soft story” refers to structures built over large open spaces at ground level — e.g., garages, carports, retail outlets, etc. The 1989 Loma Prieta and 1994 Northridge Earthquakes demonstrated the vulnerability of such buildings to extensive damage or collapse, resulting in casualties, injuries, fires from broken gas lines, and significant property damage.

If you own a multi-unit “soft story” building that has not been seismically retrofitted, you could be subject to costly fines if you’re not in compliance with local ordinances regarding retrofits.

Plus which, mortgage holders and insurance companies are now likely to insist that owners of such properties undertake seismic retrofits, whether mandated by law or not.

The inconvenience and expense of retrofitting your building may seem difficult to justify in today’s economy. Tenants may need to be relocated, and financing will have to be obtained.

There are significant benefits, however, that far outweigh the expense. A seismic retrofit will help safeguard the lives of your your tenants and your neighbors, protect your property and equity, and limit your exposure to lawsuits.

And the longer you wait to retrofit, the more it’s going to cost you. As you may have noticed, there’s a building boom under way in the Bay Area. Licensed and experienced contractors and skilled workers will be in increasingly short supply. We recommend that you get started now, so you can get the best possible solution at the lowest possible cost.

For the most cost-effective retrofit solutions, St. Onge & Associates is by far your best choice. • We have over 35 years’ experience in multi-unit, residential structural design, including seismic retrofits. • We pioneered performance-based structural design in the residential sector worldwide with the first cost-effective damper system for seismic resistance.
• And we’ve worked extensively inside and with city governments, so we know how to expedite the permitting, inspection and approval process.

As a building owner or property manager, you’ll find our experience and know-how extremely valuable in helping you control costs while meeting all the required deadlines for compliance. And once we’ve delivered the retrofit design, we can help you find a reliable and experienced contractor to complete the work.

Call us today for a free telephone consultation!

*Based on a recent comprehensive study by leading scientists, there is a 99% chance of a 6.7 earthquake in California within the next 30 years. Earthquakes of such magnitude can be deadly, as evidenced by the aftermath of the 1989 magnitude 6.9 Loma Priete and the 1994 magnitude 6.7 Northridge earthquakes.