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On the anniversary of the 1906 San Francisco Earthquake, Mayor Ed Lee signed into law the Mandatory Soft Story Retrofit Ordinance. This legislation requires the evaluation and retrofit for “multi-unit soft-story buildings,” defined as: Wood-frame structures, containing five or more residential units, having two or more stories over a "soft" or "weak" story, and permitted for construction prior to January 1, 1978.

Mayor Ed Lee, President Chiu, Supervisors Breed and Wiener with Director of Earthquake Safety, Patrick Otellini at the 1906 Earthquake commemoration and signing of the Soft Story Ordinance.

The Mandatory Wood Frame Retrofit Program 

ESIP Task A.3.a

This site is a guide for San Franciscans to get up to date information about the Mandatory Soft Story Retrofit Ordinance and its requirements. Also, please note that throughout the page there are several links embedded into the content. These links provide additional information. Please check back regularly for updates! Please contact the Department of Building Inspection (DBI) for further questions.

The DBI Soft Story Program
415-558-6699 and softstory@sfgov.org

Ordinance and Timeline

Noticing and Screening

Soft Story Retrofit Information Workshop

Earthquake Retrofit Fair

Tenants and Property Owners

Engineers and Contractors


Liquefaction and Liquefaction Application 


Retrofit Solutions Research

Revision Date: December 10, 2013

Ordinance and Timeline

This ordinance, located here for download, requires the retrofit of all San Francisco buildings that meet ALL of the following criteria:

  • Wood frame construction (Type V), and
  • Application of permit for original construction was prior to January 1, 1978, and
  • Five or more residential units, and
  • Two or more stories over a basement or underfloor area that has any portion extending above grade, and
  • A soft story condition that has not been seismically strengthened to the standards set forth in the ordinance.

The ordinance was signed into law on April 18, 2013 at the annual commemoration of the 1906 San Francisco Earthquake and became operative as of June 17, 2013 and is current law in San Francisco. Currently, buildings potentially within the scope of this ordinance have been noticed.

Please see the below for more information about the noticing, screening and tiers, as well as information for tenants, property owners, and engineers.

Noticing and Screening

On September 15, 2013 the City issued notices to all wood frame buildings containing five or more dwelling units, two or more stories, and permitted for construction prior to January 1978. Notices were sent to building owners at the address used for property tax notification within the Assessor's Office databases. Check out our Concentration Map--this map shows the concentration, by voting precinct, of wood frame, five or more unit, three or more story, pre-1987 buildings 

DBI Leaders and Director Otellini held a workshop for hundreds of property owners
with questions about soft story

Video recording of the October 28, 2013 ESIP and DBI hosted Mandatory Retrofit Program Workshop

Please note: Noticed buildings are not necessarily soft story buildings or necessarily within the scope of this program. All owners (or agents) of noticed buildings are required to go through a screening process, consisting of an engineer or architect-completed screening from that determines if each building is within the scope of the program and requires retrofit. 

** These forms are all required to be submitted to the Department of Building Inspection by September 15, 2014.**

The complete noticing pool is available online
at www.sfdbi.org/softstory

Buildings within the scope of the program that have completed work to the standards of the ordinance, have completed an AB-094 voluntary retrofit, or are not soft story buildings will not be required to go any further than the screening process in the program by opting out of the program and its requirements using the optional evaluation form or the screening form respectively. Both forms must be completed in all cases by a licensed engineer or architect, except in cases where AB-094 work was completed.

After screening, each building subject to the ordinance must be evaluated and begin the process of complying with the ordinance. The screening process places each building into one of four compliance tiers (below). This tiered approach will allow work to be phased and account for many of the conditions present within this subset of San Francisco's unique building stock.

For more details about Screening Forms and permitting please visit the Department of Building Inspection's Soft Story website.

Compliance Tiers

Tier I- Any building containing educational, assembly, or residential care facility uses (Building Code Occupancy E, A, R2.1, R3.1, or R4).

Tier II- Any building containing 15 or more dwelling units.

Tier III- Any building not falling within another tier.

Tier IV-  Any building containing ground floor commercial uses (Building Code Occupancy B or M), or any building in a mapped liquefaction zone.


Submittal Procedures

Please see the Department of Building Inspection's Soft Story website for up to date submittal procedures at www.sfdbi.org/softstory.

Tenant and Property Owners

Director Otellini presenting the Soft Story Ordinance to SFFD NERT Volunteers

Here are some important facts about the ordinance. Note, this section will be updated in the future as needed.

  • All properties potentially within the scope of this ordinance (according to Department of Building Inspection and Assessors Office records) were noticed on September 15, 2013. See here for noticing information.
  • The screening form and optional evaluation form must be completed by a licensed engineer or architect, with the exception of those buildings with work completed under the AB-094 program.
  • The Structural Engineers Association of Northern California offers a Structural Engineer Referral List, linked here.
  • The work specified by the ordinance for buildings requiring retrofit will almost always be limited to the ground floor areas, minimizing the impacts on residents of the building.
  • All work within the scope of this ordinance, as certified per San Francisco Rent Board procedures governing "Seismic Work Required by Law," will be subject to related passthrough regulation and allowances. This work may be passed along at 100%. Although, tenants facing hardship may use the hardship appeal process for passthroughs. Tenants meeting Rent Board criteria will be able to apply for appeal on the basis of financial hardship passed through rent increases resulting from the work. Please click here for that application.
  • Retrofits for buildings typically cost between $60,000 and $130,000 per building. The City has worked closely with local finance industry leaders to assemble a menu of finance options. Please see our Finance Section for more details.
  • This work may trigger disabled access upgrades to commercial spaces. A few important facts to note: (1) Residential spaces are exempt from compliance in all buildings constructed prior to March 13, 1991; (2) Any privately owned building with ground-floor commercial spaces, the San Francisco Building Code, Section 1134B requires 20% of construction costs be spent on disabled access improvements when projects are under the annual threshold of $139,934.96; (3) Unreasonable Hardship Requests (UHR) may be granted per San Francisco Building Code, Section 1134B.
  • IMPORTANT:  There is currently NO, and has never been an official list of "unsafe" properties. Until a licensed design professional has done a building assessment, there is no such information on any specific building. All addresses potentially subject to this ordinance will be posted on the Department of Building Inspection's Soft Story Program website, located at www.sfdbi.org/softstory.
  • On October 10, 2013, Mayor Ed Lee signed into law provisions that clarify the existing process for residential tenant financial hardship, allowing tenants who can not afford the capital improvement passthrough of the costs of a mandatory seismic retrofit a clearer and simplified path to being granted a hardship exemption as well as clarifying those procedures for property owners. The language of the ordinance can be downloaded here. Also, please contact the San Francisco Rent Board for question at 415-252-4602.

Engineers and Contractors

The City is legally unable to recommend engineers and contractors at this time, however there are resources available, listed here:

Also, the City intends to hold workshops to train design professionals of the implementation of the technical requirements of the ordinance and a list of those participating will be available. There are several options for design professionals to use to meet the requirements of the ordinance. The options are:

  • FEMA P-807, Seismic Evaluation and Retrofit of Multi-Unit Wood-Frame Buildings With Weak First Stories, as detailed in an Administrative Bulletin to be prepared pursuant to 3406B.3 of this ordinance, with the performance objective of 50 percent maximum probability of exceedance of Onset of Strength Loss drift limits with a spectral demand equal to 0.50 SMS, or 
  • ASCE 41-13, Seismic Evaluation and Rehabilitation of Existing Buildings, with the performance objective of Structural Life Safety in the BSE-1E earthquake, or 
  • ASCE 41-06, Seismic Rehabilitation of Existing Buildings, with the performance objective of Structural Life Safety in the BSE-1 earthquake with earthquake loads multiplied by 75 percent, or 
  • For evaluation only, ASCE 31-03, Seismic Evaluation of Existing Buildings, with the performance level of Life Safety, or 
  • For retrofit only, 2012 International Existing Building Code (IEBC) Appendix A-4, or
  • Any other rational design basis deemed acceptable by the Department that meets or exceeds the intent of the above standards.
Please see our Retrofit Solutions Research section for information on the work happening now.

The Department of Building Inspection promoted Robert Chun in Plan Review Services to the position of Program Manager for the Mandatory Seismic Retrofit Program (MRP) in DBI. See the press release here. (ESIP Task A.5.d)


Liquefaction is a condition where loose sand and silt that is saturated with water can behave like a liquid when shaken by an earthquake.

California Geological Survey Liquefaction Display

Liquefaction Application: The City worked with Code For America to create an application that allows the user determine if their building is in a mapped liquefaction area. Liquefaction is a phenomenon where soft soil interacts with water below the surface and weakens. In 2000 the California Geological Survey produced a map of these areas. San Francisco has adopted this map and made it part of the criteria for buildings within the definition of Tier IV.

How to use this application: The user would go to the San Francisco Property Information Map and determine their property's block and lot identifier by inputting their address. From there, the user inputs their block and lot below and clicks search. The application will tell the user if their building is within this mapped area. Please then use this information to enter your block and lot in the following format:

Block: Block Numbers ALWAYS contain four numbers, so leading zeros must be included. (Example:  1234, 0595, or 0078)

Lot: Lot numbers ALWAYS contain at least three numbers (and possibly a letter), so leading zeros must be included. (Example:  123, 075, 001, 002A)

Note: This application indicates a building's potential location within a liquefaction area, but does not make claims about specific soil conditions at the site of the building. A licensed soil specialist should be contacted for this level of detail. This application is intended only as a guide as part of the Mandatory Seismic Retrofit program.


Seismologists predict a 63% probability that the Bay Area will experience a magnitude 6.7 earthquake in the next 30 years. After the devastating but actually very small 1989 Loma Prieta Earthquake, the City initiated the Community Action Plan for Seismic Safety (CAPSS). Working with industry experts and community members to understand the likely impacts on San Francisco from the next major earthquake, the CAPSS researchers investigated the likely impact of soft story buildings. The CAPSS study report “Earthquake Safety for Soft-Story Buildings” (ATC 52-3) goes into detail about soft-story multi-unit buildings, the program, and the impact of these buildings on the City’s resilience. Upon the completion of this study, the recommendations of the CAPSS project were turned into the 50 tasks of the Earthquake Safety Implementation Program (ESIP). The Mandatory Soft Story Retrofit Ordinance is one of these tasks.


CAPSS soft story image 1
Soft-story multi-unit buildings damaged or destroyed
by the 1989 Loma Prieta earthquake.


Soft-Story Multi-Unit Buildings, Summary

According to the CAPSS study, many of San Francisco’s wood-frame multi-unit residential buildings would be seriously damaged in a future probable earthquake. A significant number could collapse. The scope of this damage could cause many causalities and injuries, as well as set back the City’s post earthquake recovery, and could even irrevocably change the character and affordability of the City. Many multi-story wood frame buildings were built before modern code changes adopted in 1978 (California Health and Safety Code Section 19161). These buildings have a structural weakness in the ground floor called a “soft story” or “weak story.”


Soft Story Condition

This condition is due to large openings in their perimeter walls and to a lack of interior partition walls at the ground level. Usually, perimeter wall openings at the ground level make way for garage doors or large windows. Interior spaces used for retail and garages often have few partition walls. The open condition makes the ground level significantly weaker and more flexible than the floors above it. During strong earthquake shaking, these “soft” ground level walls cannot support the side-to-side or front-to-back- movement of the stiff and heavy mass of the stories above them, lending to damage and, in the worst of cases, to collapse.


CAPSS soft story image 2


CAPSS Analysis:  The Impact of Soft Story 

Retrofitting these building is relatively simple and inexpensive, providing a great deal of value in safety for the occupants and owner and allowing the City to rebound more quickly after an earthquake. The CAPSS report analyzed these buildings, coming to the following determinations:

  • There are approximately 4,300 wood-frame buildings built before January 1, 1978, in San Francisco with five or more residential units on two or more stories. All of these buildings may have a soft story condition, but CAPSS determined that about 2800-2900 of these buildings likely have this condition. This was determined through a sidewalk visual survey.
  • As they stand now, 43 to 85 percent of these buildings would be posted with an UNSAFE placard (red-tagged) after a probable strong earthquake, meaning 1200-2400 red-tagged buildings.
  • One quarter of these red-tagged buildings would be expected to collapse. This represents 300 to 850 buildings. Collapse threatens lives. Also, these buildings are almost entirely rent-controlled apartments, which would be rebuilt. If rebuilt they would not be subject to rent control under state law or may not even be apartment buildings at all. Also, this would be a significant blow to the City’s architectural and demographic character.
  • Nearly 58,000 people occupy these buildings, and they house nearly 2,000 businesses employing nearly 7,000 people.
  • With retrofit, collapses could be reduced to less than one percent of these buildings.
  • Retrofitting all of the buildings in this subset to a recommended level that would allow most of them to be occupied after a large earthquake would cost approximately $260 million, costing nearly $1.5 to repair and replace after a large quake.
  • Seismic retrofit of these buildings has been estimated to cost between $60,000 and $130,000 per building in direct construction costs, taking two to four months with construction limited to the ground floor only.
  • These buildings are found city-wide, with substantial concentrations in the Mission, Western Addition, Richmond, Pacific Heights, North Beach and Marina neighborhoods.

Please also take a moment to check out the technical documentation that explains the process through which this information was gathered. The document is called ATC 52-3 Earthquake Safety for Soft-Story Buildings, Technical Documentation.

Retrofit Solutions Research

Many private and public institutions are hard at work developing retrofit solutions that will allow for cost effective and simple improvements to buildings all over San Francisco. This is only some of work underway. A lot of great work is being done in this field. Please direct examples or work to the EPICENTER, our upcoming pop-up collaborative space for earthquake innovation, policy and education.

NEES @ UC San Diego
The Network for Earthquake Engineering Simulation, part of the National Science Foundation (NSF), is in the process of testing a four-story wood frame building with various retrofit solutions on the shake table at the University of California, San Diego. Please visit www.nees.org for more information.

Four-story wood frame building on UCSD's shake table

UCSD's world-famous shake table

Last updated: 11/5/2014 4:47:41 PM