Bolthole Index

San Mateo County, California

Zoning, building permits and septic rules in South San Francisco, California

South San Francisco, California runs its own zoning under Title 20 of the city code1, and the city's Building Division issues building permits2. Sewage inside the city goes to the public sanitary sewer3. Septic and well permits in San Mateo County come from County Environmental Health Services4. Land outside city limits follows the county's rules.

At a glance

Zoning
City zoning, Title 20 of the city code1
Building permit
Issued by the city Building Division2
Sewer
Sanitary sewage goes to public sewers3
Septic and wells
San Mateo County Environmental Health Services issues the county's septic and well permits45
Smallest lot, RL-8
5,000 sf (corner lots 6,000 sf)6
Smallest lot, RL-2.2
32,600 sf7
RV living
State rule: not for permanent dwelling; city rule unconfirmed8
Owner-builder
State exemption is conditional9

Who to call

Building permits

City of South San Francisco Building Division

Building permits, plan review and inspections inside South San Francisco city limits

(650) 829-6670

Zoning

City of South San Francisco Planning Division

Zoning questions and planning review inside South San Francisco city limits

(650) 877-8535

planning@ssfca.gov

315 Maple Avenue

Septic permits

San Mateo County Environmental Health Services

Septic (OWTS) permits and water-well drilling permits in San Mateo County

(650) 372-6200

Contact details are copied from each office’s official page and were checked against it on October 24, 2026.

Off-grid gear

Going off-grid in South San Francisco means bringing your own water and power. The kit we’d start with:

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Does South San Francisco have zoning, and what does it mean for lots and setbacks?

South San Francisco, California has its own zoning. The city classifies land into zoning districts set out in Title 20 of the city code1, and the residential districts are RL-2.2, RL-8, RM-22, RH-37.5, RH-50 and RH-18010.

Lot size depends on the district. In RL-8, the minimum lot area is 5,000 sf and the minimum lot width is 50 ft6. In RL-2.2, the minimum lot area is 32,600 sf and the minimum lot width is 120 ft7. Hillside lots can have those minimums modified7.

Height and coverage also vary. RL-8 lots allow primary buildings up to 28 ft and 50 percent lot coverage1112. RL-2.2 lots allow 30 ft and 40 percent coverage1314. Ask the Planning Division which district a parcel is in before you buy15.

Do you need a building permit in South San Francisco, and who issues it?

Inside South San Francisco city limits, the city's Building Division issues building permits and takes in plans for review2. Call (650) 829-6670, option 12.

We could not confirm the city's local amendments, inspection steps or fees, so ask the Building Division what a specific project needs. California's statewide building code applies to the state's buildings and structures, and the local building department decides how the permit application date is set16.

The San Mateo County Building Division handles building permits for unincorporated land only, and the county page does not apply inside the city.

How do septic permits work inside South San Francisco?

Sanitary sewage from property in South San Francisco must go only into public sanitary sewers, except as Chapter 14.08 of the city code otherwise provides3. A sewer connection fee is paid when the building permit is issued3. We could not confirm a city septic provision, so a lot without sewer access needs a call to the city before you plan around a septic system.

For septic systems anywhere in San Mateo County, everyone who installs an individual sewage disposal system needs a permit from Environmental Health4. Contact San Mateo County Environmental Health Services at (650) 372-620017. Well drilling in the county needs a drilling permit from Environmental Health Services5.

Can you live in an RV or tiny home in South San Francisco?

We could not confirm South San Francisco's own rules for living in an RV, camping on private land or occupying a tiny home. Ask the Planning Division15.

California's statewide position is that RVs are not intended for occupancy as permanent dwellings, and unless a local ordinance allows otherwise they generally may be occupied only in mobilehome parks or special occupancy parks8. A tiny home must meet the standards of an approved structure type, such as a manufactured home, a California Residential Code home or an RV, and a unit that fits none of them is illegal to occupy18.

Building a home in South San Francisco: the steps, in order

  1. Confirm the parcel's zoning district and its lot size, height and coverage limits with the Planning Division15.
  2. Check the sewer connection at the property; sewage goes to public sewers3.
  3. Apply for the building permit through the Building Division2.
  4. If you are the owner-builder, review the state's conditional exemption, which turns on who does the work and whether the structure is for sale9.
  5. For a septic system or well in San Mateo County, apply to County Environmental Health45.

What stays with San Mateo County, and what to check before you buy

Septic and well permits come from the county, not the city45. Land outside city limits falls under San Mateo County's rules for unincorporated land, not the city's.

For context, county-level figures: the typical home value in San Mateo County is about $1,595,76419, and the median property tax bill is $9,167 a year20. Parcels near San Francisco International Airport may need an airspace evaluation under the city's zoning code11.

Watch-outs

  • We could not confirm the city's building code amendments, inspection rules, permit fees, floodplain rules or accessory dwelling unit rules; ask the Building Division and Planning Division before relying on them215.
  • Hillside lots, with an average slope of 15 percent or more, can have minimum lot size and setbacks modified under the city code6.
  • Mixed-use, form-based and specific-plan districts, such as the Lindenville Specific Plan, have their own standards outside the residential rules above10.

Sources

  1. Chapter 20.060: Establishment of Conventional Zoning Districts (eCode360) (South San Francisco), quoted and re-checked
  2. City of South San Francisco Building Division (ssf.net)
  3. Chapter 14.08: Water Quality Control (eCode360) (South San Francisco), quoted and re-checked
  4. Land Use, Septic & Wells, quoted and re-checked
  5. Land Use, Septic & Wells, quoted and re-checked
  6. Chapter 20.070: Residential Zoning Districts (eCode360) (South San Francisco), quoted and re-checked
  7. Chapter 20.070: Residential Zoning Districts (eCode360) (South San Francisco), quoted and re-checked
  8. hcd.ca.gov (California statewide rule), quoted and re-checked
  9. California Business and Professions Code Section 7044 (California statewide rule), quoted and re-checked
  10. Chapter 20.070: Residential Zoning Districts (eCode360) (South San Francisco), quoted and re-checked
  11. Chapter 20.070: Residential Zoning Districts (eCode360) (South San Francisco), quoted and re-checked
  12. ecode360.com (South San Francisco), quoted and re-checked
  13. ecode360.com (South San Francisco), quoted and re-checked
  14. ecode360.com (South San Francisco), quoted and re-checked
  15. City of South San Francisco Planning Division (ssf.net)
  16. Approved Building Standards (California statewide rule), quoted and re-checked
  17. San Mateo County Environmental Health Services (smcgov.org)
  18. Information Bulletin 2016-01: Tiny Homes (California statewide rule), quoted and re-checked
  19. Typical home value (Zillow): Bolthole Index county data
  20. Median property tax bill: Bolthole Index county data

Written October 24, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

Answers from the rulebook for South San Francisco

South San Francisco’s own rules

  • Local zoningPresent (with conditions)

    Land inside South San Francisco city limits. The city's own zoning code is Title 20 (Zoning).

    • Zoning districts and regulations are set by Title 20 of the city code.
    • Residential districts are detailed in Chapter 20.070 (see related claims).
    “the city shall be classified into zoning districts or zones, the designation and regulation of which are set forth in this title as follows:”
  • Zoning districtsPublished (with conditions)

    Residential zoning districts inside South San Francisco city limits (RL-2.2, RL-8, RM-22, RH-37.5, RH-50, RH-180).

    • Chapter 20.060 lists the conventional zoning districts; Chapter 20.070 sets use regulations and development standards for the residential districts.
    • Mixed-use, form-based, and specific-plan districts (for example Chapter 20.150, Lindenville Specific Plan) are outside this claim.
    “table 20.070.003: development standards – residential zoning districts, establishes the development standards for the residential zoning districts.”
  • Minimum lot sizeSpecified

    Land zoned RL-8 (Low Density Residential, single-family and attached single-family) inside South San Francisco city limits.

    • Hillside lots (average slope 15 percent or greater): the minimum lot size and front and rear setbacks may be modified under section 20.310.002 (note b).
    • Corner lot minimum is 6,000 sf (Table 20.070.003).

    minimum lot area: >= 5000 sf · minimum lot area, corner: >= 6000 sf · minimum lot width: >= 50 ft · minimum lot width, corner: >= 60 ft

    “lot size min. lot area 32,600 sf (b) 5,000 sf (b) 5,000 sf (b) 5,000 sf (b) 5,000 sf (b) 20,000 sf (b) min. lot area, corner 32,600 sf (b) 6,000 sf (b)”
    One more reviewed finding on this topic
  • Lot coverageSpecified

    Lots zoned RL-2.2 inside South San Francisco city limits.

    • Floor area ratio is separately limited to 0.5 or 2,000 sf, whichever is greater (Table 20.070.003).

    maximum lot coverage: <= 40 percent

    “max. lot coverage 40% 50% 50% 65% 65% 85%”
    One more reviewed finding on this topic
    • Specified — Lots zoned RL-8 inside South San Francisco city limits.
      “max. lot coverage 40% 50% 50% 65% 65% 85%”
  • Building heightSpecified

    Primary buildings on RL-2.2 lots (low-density single-family) inside South San Francisco city limits.

    • Note d: height may be increased to a maximum of 35 feet with a minor use permit, subject to the same findings as RL-8.

    maximum primary building height: <= 30 ft (2 stories)

    “max. primary building (ft/stories) 30 ft/2 stories 28 ft/2 stories (d)”
    One more reviewed finding on this topic
    • Specified — Primary and accessory buildings on RL-8 lots inside South San Francisco city limits.
      “max. primary building (ft/stories) 30 ft/2 stories 28 ft/2 stories (d) 35 ft/3 stories (f) 50 ft/4 stories (d)”
  • Mandatory utility hookupSewer (with conditions)

    Sanitary sewage from property inside South San Francisco city limits.

    • Sanitary sewage must go only into public sanitary sewers, except as otherwise provided in Chapter 14.08.
    • A sewer connection fee is paid at building permit issuance, or before the connection is operational if no building permit is needed.
    • Connections are made at the point of lowest elevation on the city sanitary sewer main or manhole fronting the property, unless the city permits otherwise (Chapter 14.14).
    • No distance-based availability rule was located; water connection was not established and is not claimed here.
    “sanitary sewage shall be discharged only into public sanitary sewers, except as otherwise provided.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask South San Francisco or San Mateo County directly.

  • Building permit — General building permit requirement for new homes inside South San Francisco city limits.
  • Owner-builder exemption — Owner-builder exemption inside South San Francisco city limits.
  • Building code adopted — Building code adoption inside South San Francisco city limits.
  • Inspections — Building inspection requirement inside South San Francisco city limits.
  • Certificate of occupancy — Certificate of occupancy requirement inside South San Francisco city limits.
18 more unanswered
  • Minimum dwelling size
  • Living in an RV
  • Camping on your land
  • Tiny homes
  • Manufactured homes
  • Accessory dwellings
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Agricultural exemption
  • Subdividing land
  • Driveway access
  • Building in a floodplain
  • Short-term rentals
  • Permit fees
  • Permit process

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Unanswered questions are usually a sign that South San Francisco publishes no rule on the point, not that none exists. San Mateo County’s page lists the county offices to call.

← All of San Mateo County: county rules, score and offices