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San Joaquin County · Building on your lot

Building in a flood zone in San Joaquin County

Lowest floor at least 1 foot above 100-year flood elevation; Zone A/AO: 1 foot above FIRM depth, or 2 feet above ground if none.

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Key points

  • New-home floors: Lowest floor at least 1 foot above 100-year flood elevation; Zone A/AO: 1 foot above FIRM depth, or 2 feet above ground if none.

Each rule below links to the section of the San Joaquin County Municipal Code it was read from, with the code text one click away (checked October 2026). General information, not legal advice.

What San Joaquin County's code says

San Joaquin County code What San Joaquin County's code adds
Floodplain permit
  • A permit is needed; in flood fringe areas, data must show the 100-year flood rises no more than 1 foot.
    Applies: Development in special flood hazard areas.
    § 9-703.070 · code text
    Prior to approving an application for a permit to develop within a special flood hazard area, the Floodplain Administrator shall be provided with technical data to determine that the following are true:
Height of the lowest floor
  • The lowest floor must be at least 1 foot above the 100-year flood elevation.
    Applies: New or substantially improved homes and other structures in flood hazard areas; nonresidential buildings may be floodproofed instead.
    § 9-703.130 · code text
    All new construction and substantial improvements of any structure in areas of special flood hazard shall have the lowest floor, including basement, elevated to at least one (1) foot above the one hundred (100) year flood elevation.
  • The lowest floor must be at least 1 foot higher than the FIRM depth number above the highest nearby ground.
    Applies: New or substantially improved homes and other structures in Zone A or AO with a depth number.
    § 9-703.130 · code text
    All new construction and substantial improvement of any structure in FIRM Zone A or AO shall have the lowest floor, including the basement, elevated at least one (1) foot higher than the depth number specified in feet on the FIRM measured from the highest adjacent grade, or at least two (2) feet if no depth number is specified.
  • The lowest floor must be at least 2 feet above the highest nearby ground.
    Applies: New or substantially improved homes and other structures in Zone A or AO with no depth number.
    § 9-703.130 · code text
    All new construction and substantial improvement of any structure in FIRM Zone A or AO shall have the lowest floor, including the basement, elevated at least one (1) foot higher than the depth number specified in feet on the FIRM measured from the highest adjacent grade, or at least two (2) feet if no depth number is specified.

Who this affects

HomeownersContractorsDesigners

Frequently asked questions

What are the rules for building in a San Joaquin County flood zone?

Lowest floor at least 1 foot above 100-year flood elevation; Zone A/AO: 1 foot above FIRM depth, or 2 feet above ground if none.

General information, not legal advice.

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San Joaquin County Municipal Code — full text