Floodplain Management Ordinance

Floodplain Management Ordinance

The City and County of San Francisco is participating in the National Flood Insurance Program (NFIP). Under this program, which is managed by the Federal Emergency Management Agency (FEMA), the federal government provides federally subsidized flood insurance at affordable rates to San Francisco homeowners, renters, and businesses.

As a condition of participating in the NFIP, the City has adopted and enforces a Floodplain Management Ordinance (FMO) intended to reduce the risk of damage from flooding. The ordinance requires new construction and buildings undergoing substantial improvements in designated flood hazard areas to be protected against flood damage. This means that if you own a building in San Francisco’s Flood Hazard Area, and you elect to perform a substantial improvement, you may be required to elevate or flood-proof your building.

The ordinance applies to all properties in the Flood Insurance Rate Map (FIRM). Regulated Special Flood Hazard Areas (SFHAs) are delineated on Flood Insurance Rate Maps (FIRMs) issued by the Federal Emergency Management Agency (FEMA). The San Francisco Planning Department includes the FIRM information on its Property information Map (PIM), in the “Environmental Information” tab. The FIRM maps can also be viewed at FEMA’s online Map Service Center. The “Make a FIRMette” feature enables you to save or print a selected portion of a map along with identifying information.

PLEASE NOTE: The Flood Management Ordinance DOES NOT apply to structures within the SFPUC 100-year flood map.

The specific requirements for a floodplain construction project depend on the flood zone and the type of development. The basic standards that must be met by any floodplain construction are:

Proposed development must be reasonably safe from flood damage, which for most buildings means elevated above the height of floodwaters.
Proposed development shall not result in physical damage to any other property. Technical analysis may be required if there is potential for increased flood heights, diversion of flow, flotation of materials, or release of pollutants.

Requirements

Construction projects in the Flood Hazard Area must conform to the requirements outlined below.

California Building Code Section 1612
ASCE 24-14
SFDBI Information Sheet G-28

All building permit applications for projects in the Special Flood Hazard Area must include a completed Floodplain Management Ordinance Screening Form, which can be found attached to Information Sheet G-28. If the project is the construction of a new building/structure or substantial alteration of an existing structure, the structure will need to be made flood resistant through elevation, flood-proofing, or some combination of the two.

Applicability

The floodplain management requirements apply to residential and non-residential buildings located in SFHAs, including both private and public buildings. The requirements do not apply to other types of infrastructure, such as streets, utilities, public transportation infrastructure, waterfront infrastructure, landscaping, and natural features.

For buildings in SFHAs, the requirements apply to:

New construction
Substantial improvement or repair of existing buildings. A “substantial” improvement or repair is defined as one in which the cost of the improvement or repair exceeds 50% of the market value of the structure.

Construction Requirements

The Floodplain Management Ordinance references the San Francisco Building Code, which incorporates the flood-resistant construction standards of the California Building Code (CBC). These standards apply to construction of new buildings and substantial improvement/repair of existing buildings in SFHAs.

These standards include the following (this a partial list only: refer to the CBC, ASCE 24-14, and DBI Information Sheet G-28 for comprehensive details on the requirements):

The lowest floor, including a basement, of the structure must be elevated above the applicable Base Flood Elevation (BFE) to the Design Flood Elevation (DFE).
Non-residential structures in certain flood zones may be flood-proofed instead of elevated. The building must be flood-proofed to at least the Design Flood Elevation.
In an elevated structure, areas below the DFE must be constructed of flood-resistant materials .
Attendant utilities must be designed to prevent infiltration of floodwaters or elevated to at least the DFE.

Flood Management Ordinance Exceptions/Variances

The City may issue a variance to the requirements in the following circumstances:

The structure is historic. The ordinance identifies the types of structures that may meet this definition.
The structure constitutes a “functionally dependent use.” As described in the ordinance, this type of facility cannot perform its intended purpose unless it is located or carried out in close proximity to water. For example, docking facilities and facilities used for loading and unloading watercraft may be functionally dependent.
The variance is necessary to alleviate an exceptional hardship.

As applicable, the Planning Department and DBI will evaluate the need for variances on a case-by-case basis.

Documentation Requirements

Building permit applications for parcels in the SFHA must include the following Flood Hazard Zone Protection Checklist attached to Information Sheet G-28.

Construction of new buildings or structures or substantial improvements/repairs to existing buildings or structures will require the following document(s) prior to final sign-off or granting of a Certificate of Final Completion and Occupancy:

FEMA Elevation Certificate
For projects utilizing Dry Flood-proofing: FEMA Flood-proofing Certificate

Reference Documents

California Building Code Sec. 1612

Flood-Resistant Design and Construction, American Society of Civil Engineers (ASCE) 24-05, purchase at ASCE, highlights available at FEMA.

DBI Information Sheet G-28

FEMA Documents

FEMA Flood Publications

Openings in Foundation Walls and Walls of Enclosures, Technical Bulletin 1, FEMA FIA-TB-1 (2020)

Flood Damage-Resistant Materials Requirements for Buildings Located in Special Flood Hazard Areas, Technical Bulletin 2, FEMA FIA-TB-2 (2008), includes lists of acceptable materials for flood-resistant construction.

Non-Residential Floodproofing - Requirements and Certification, TB 3 (2020):

Protecting Building Utilities from Flood Damage: Principles and Practices for the Design and Construction of Flood Resistant Building Utility Systems, FEMA 348 (1998).

Wet Floodproofing Requirements , Technical Bulletin 7, FEMA FIA-TB-7 (2020), includes planning, safety, and engineering considerations for wet floodproofing.

Substantial Improvement and Substantial Damage Desk Reference, FEMA P-758 (May 2010).

Answers to Questions About Substantially Damaged Buildings, FEMA 213 (1991).

Additional Information

For additional information, visit the following.

San Francisco’s Floodplain Management Program

https://onesanfrancisco.org/San-Francisco-Floodplain-Management-Program

Flood Insurance Rate Map Panels for San Francisco

https://msc.fema.gov/portal/home

San Francisco Public Utilities Commission 100-Year Storm Flood Risk Map

https://www.sfwater.org/floodmaps

San Francisco Information Future Inundation Due to Sea-Level Rise

https://www.onesanfrancisco.org/node/148