With a population density of about 18,451 people per square mile (7,214 people per km²), San Francisco is the most densely populated large city in California and the second-most densely populated major city in the United States, behind New York City. “The City” itself, happens to be also situated almost directly on top of the San Andreas Fault, which runs 750 miles through the state of California. How does this relate to non-ductile concrete and why should you care as a property owner?!
On April 16th, 2024, Mayor London Breed issued an Executive Directive instructing City Departments to develop legislation to identify concrete buildings that may be vulnerable in major earthquakes. The Directive serves to enhance San Francisco’s seismic safety by protecting life and public safety, preserving housing and critical buildings, preparing the City for expedited post-earthquake recovery, and safeguarding the local economy. Link to the Executive Directive can be found here (LINK).
Furthermore, Mayor London Breed’s April 2024 Executive Directive has instructed that the following be completed by October 16, 2024:
I. Draft Legislation that Mandates Screening Concrete Buildings for Seismic Vulnerability: The Office of Resilience and Capital Planning and the Department of Building Inspection shall draft legislation which mandates completion of a building information reporting checklist to identify potentially vulnerable concrete buildings.
II. Publish Retrofit Standards in the San Francisco Building Code: The Department of Building Inspection shall develop and publish retrofit criteria for concrete buildings in the San Francisco Existing Building Code.
What’s Next?
Currently, this pending San Francisco Non-Ductile Concrete Ordinance is strictly voluntary. In the future it will likely be mandatory (timing is unknown). The ordinance Covers all concrete and tilt-up buildings with certain exemptions. Currently developing code language for SFBC (but it will just be a placeholder – work is voluntary at this point). First mandatory item will likely be completion of a screening form to see if your building would fall under the future ordinance (according to Forrell | Elsesser @ forell.com).
The purpose of the purpose screening form, likely would start with the buildings currently on “the list” of buildings believed to be concrete. “The list” is not very accurate. About 3,000 buildings on the list based on Google Earth and sidewalk surveys. There are buildings that are not on the list that would fall under the ordinance. This will be used to get a better sense of how big the problem is, and to remove buildings from the future ordinance scope (according to Forrell | Elsesser @ forell.com).
According to the ONESF – Stakeholder Engagement for Concrete Building Safety Program | April 2024 please review the following items for more information about the proposed program:
Technical Recommendations | Concrete Buildings:
Buildings subject to the ordinance: Concrete buildings, exempting those with one or more of the following conditions:
• Age: Built 2000 or later, or permit application date 7/1/1999 or later. (1997 Uniform Building Code adoption)
• Size: Building area smaller than 3000 square feet.
• Height: One story above grade.
• Height: Two stories above grade and no concrete columns nor wall piers.
• Construction type: Complete steel frame supporting gravity floor load and roof load.
• Construction type: Non-concrete building. Concrete limited to floors, roofs, foundations, basements.
• Prior retrofit: Previous retrofit satisfying triggered retrofit requirement in past 15 years.
• Use: One- and two-family residential. R-3 occupancy (1-2 unit residential) and incidental Group U occupancy (Miscellaneous, includes
barns, garages, hangars, sheds).
Rationale and Context
The primary consideration for concrete buildings is life safety.
Age: The project technical consultant recommends using the 1997 Uniform Building Code (UBC) as the cut-off year. This matches the benchmark year for concrete buildings in the upcoming ASCE-41-23 standard. While initial improvements to concrete building seismic requirements were enacted in the 1976 UBC, there have been many subsequent code improvements, including addressing irregularities in the 1988 UBC, addressing stronger near-fault earthquake in the 1991 UBC, and addressing the columns, beams, and slabs designated gravity framing in the 1997 UBC. Some of the collapses in the 1993 Guam earthquake, the 1994 Northridge earthquake, and the 2011 New Zealand earthquake occurred buildings designed in the period of 1985 to 1994 using codes compatible with US codes.
Building size: Buildings with a gross floor area smaller than 3,000 square feet are exempt from this program for simplicity and because of the potentially lower life safety risk of these smaller buildings.
Height: One-story buildings and some two-story buildings are exempt from this program because of the potentially lower life safety risk of these smaller buildings.
Construction type: These exemptions are definitional. For example, buildings with steel frames, which do not have deficiencies typical of concrete buildings, are exempt.
Prior retrofit: Buildings with prior retrofitting that meets the identified sections of past editions of the San Francisco Building Code, going back to the 2007 SFBC, are expected to have performance sufficiently similar to what results from retrofitting per the ordinance.
This exemption protects building owners who have recently made major investments in seismically upgrading their buildings from needing to make a second major upgrade.
Use: One-unit and two-unit homes are exempted because they are unlikely to be of concrete construction, and for the few that might be, they are unlikely to be as vulnerable as larger buildings.
Recommended Timeline and Schedule Categories for Concrete buildings:
Compliance Deadline – Unit: years after ordinance effective date
For more details, feel free to reach out to our team. We’ll continue to monitor the developments of this pending city and county-wide ordinance.