Bolthole Index

San Mateo County, California

Zoning, building permits and septic rules in San Bruno, California

San Bruno, California (San Mateo County) zones its own land under Title 12 of its municipal code1, and the city's Building Division issues building permits2. Septic permits are a county matter: San Mateo County Environmental Health permits individual sewage disposal systems3. San Bruno has no agricultural or rural-residential district, so this is a single-family, ADU and infill market, not open land4.

At a glance

Zoning
City of San Bruno, under its own zoning ordinance1
Building permits
Issued by the San Bruno Building Division2
Septic permits
San Mateo County Environmental Health3
R-1 minimum lot
5,000 sq ft interior lot, 6,000 sq ft corner lot5
R-1 front setback
15 ft (20 ft from sidewalk to a garage)6
ADUs
Permitted in any district where residential uses are permitted7
RV and tiny home living
Not confirmed for San Bruno; statewide, RVs are generally limited to RV parks unless a local ordinance allows more8
Owner-builder
Statewide licensing exemption; does not remove the permit requirement9

Who to call

Building permits

City of San Bruno Building Division

Building permits, plan review and inspections inside San Bruno city limits

650-616-7058

567 El Camino Real San Bruno, CA 94066

Online permits →

Zoning

City of San Bruno Planning Division

Zoning, planning applications and architectural review inside San Bruno city limits

650-616-7058

567 El Camino Real San Bruno, CA 94066

Septic permits

San Mateo County Environmental Health Services

Septic (OWTS) permits, inspections and water-well drilling permits for 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 San Bruno means bringing your own water and power. The kit we’d start with:

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Does San Bruno, California have zoning, and what does it allow?

San Bruno zones land inside its own city limits under Title 12, Article III of its municipal code1. The district list runs from R-1 through R-4 residential, neighborhood commercial, industrial, open space and planned development districts, and includes no agricultural or rural-residential district4. San Mateo County's zoning applies only to unincorporated land, not to parcels inside a city10.

In the R-1 single-family district, an interior lot needs at least 5,000 square feet and a corner lot at least 6,0005. Front setbacks are at least 15 feet, with 20 feet from the sidewalk to a garage; rear setbacks are at least 10 feet, interior sides at least 5 feet and street sides at least 10 feet, with reductions allowed on legal substandard lots6. Impervious surface is capped at 80 percent of the lot in R-111. Height is capped at 28 feet on lots under 20 percent slope, 26 feet on downsloping lots and 30 feet on upsloping lots12. Manufactured or moved-in homes face the same requirements as new infill construction13.

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

The City of San Bruno Building Division issues building permits and takes in plans for review inside city limits2. Building a new ADU or junior ADU requires a building permit once the city approves the application14. We could not confirm which minor jobs, if any, the city exempts from building permits, so ask the Building Division before assuming a project is exempt.

The county's building permit rule covers only unincorporated San Mateo County, and the county states that incorporated cities and towns administer their own permitting15. Do not send a San Bruno project to the county counter in Redwood City.

California's owner-builder exemption is a contractor-licensing exemption and does not itself remove a building-permit requirement9. Larger discretionary changes in R-1 and R-2 go through an architectural review permit decided by the community development director, with bigger deviations going to the planning commission16.

Who do you contact at the City of San Bruno about permits and zoning?

Building permits, plan review and inspections: the Building Division, reachable at 650-616-70582. Counter staff are available Monday through Thursday, 7:30 a.m. to 5:00 p.m., and the online permit portal stays open for permit requests and inspection scheduling2. Zoning questions and planning applications go to the Planning Division, which administers the city's General Plan, specific plans and zoning ordinance17. Both offices are at 567 El Camino Real2.

Septic and well questions go to a different office: San Mateo County Environmental Health Services at (650) 372-620018.

How do septic permits work in San Bruno?

San Mateo County Environmental Health Services, not the city, permits individual sewage disposal systems: anyone who installs one must have a permit from Environmental Health3. The county's staff observe and approve installation, repair, alteration or destruction of a system19. Wells work the same way, with a drilling permit from Environmental Health20.

We could not confirm whether any San Bruno lot relies on a septic system or whether the city adds its own rules for them. Ask Environmental Health and the Building Division before you plan around septic on a San Bruno parcel. Septic suitability data is only available countywide: about 16 percent of San Mateo County soils rate as not limited for a conventional drain field, so most sites would need a site evaluation or an engineered system21.

Can you live in an RV or tiny home on your land in San Bruno?

We could not confirm San Bruno's rules on long-term RV living, temporary camping or tiny homes; ask the Planning Division at 650-616-7058 before you buy17. California's statewide position is that RVs are not intended as permanent dwellings and generally may be occupied only in mobilehome parks or special occupancy parks unless a local ordinance allows otherwise8.

The clearest housing route the city's code confirms is an accessory dwelling unit. ADUs are a permitted use in any district where residential uses are permitted7. A detached ADU on a single-family lot is limited to 16 feet in height and needs 4-foot side and rear setbacks, with no setback for conversions of existing space7. A studio or one-bedroom ADU on a lot with a single-family home under 7,500 square feet is capped at 850 square feet7. The city decides ADU applications ministerially, without a public hearing16.

Building a home in San Bruno: the steps, in order

  1. Confirm the zoning district and its lot, setback, coverage and height standards with the Planning Division17.
  2. Check whether your project needs an architectural review permit; deviations from R-1 and R-2 standards may need one or planning commission approval16.
  3. For an ADU, apply for ministerial approval first, then obtain the building permit14.
  4. Apply for building permits through the city's online permit portal or at the Building Division counter2.
  5. Schedule inspections through the Building Division2.
  6. If a septic system or well is involved, get the permit from San Mateo County Environmental Health3.

What to check before you buy land in San Bruno

Confirm the district, because every dimensional standard in San Bruno depends on it; the R-1 numbers above do not apply to R-2, which has different coverage limits11. Ask whether the lot is a legal substandard lot, which can still qualify as a building site5.

If you plan to rent a unit short-term, non-hosted rentals of a whole unit are capped at 120 calendar days per year, and ADUs permitted after September 25, 2020 cannot be short-term rentals22.

Costs are county-level figures: the typical San Mateo County home value is about $1.6 million23 and the effective property tax rate is about 0.6 percent24. For land outside city limits, the San Mateo County page has the unincorporated-area rules.

Watch-outs

  • San Bruno's building permit exemptions, adopted building code, fees, floodplain rules and driveway rules were not confirmed; ask the Building Division at 650-616-7058 before you rely on any of them2.
  • San Mateo County's unincorporated-area rules, including its building permit, zoning and flood rules, do not apply inside San Bruno city limits10.
  • An ADU permitted after September 25, 2020 may not be used as a short-term rental, and no ADU may be rented for less than 30 days if permitted after January 1, 20207.

Sources

  1. Article III: Zoning - City of San Bruno, CA (eCode360) (San Bruno), quoted and re-checked
  2. City of San Bruno Building Division (sanbruno.ca.gov)
  3. Land Use, Septic & Wells, quoted and re-checked
  4. Article III: Zoning - City of San Bruno, CA (eCode360) (San Bruno), quoted and re-checked
  5. Chapter 12.200: Development Regulations for the R-1 and R-2 Zoning Districts (eCode360) (San Bruno), quoted and re-checked
  6. Chapter 12.200: Development Regulations for the R-1 and R-2 Zoning Districts (eCode360) (San Bruno), quoted and re-checked
  7. Chapter 12.90: Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360) (San Bruno), quoted and re-checked
  8. hcd.ca.gov (California statewide rule), quoted and re-checked
  9. Owner-Builder Overview, quoted and re-checked
  10. Get Zoning Information, quoted and re-checked
  11. Chapter 12.200: Development Regulations for the R-1 and R-2 Zoning Districts (eCode360) (San Bruno), quoted and re-checked
  12. Chapter 12.200: Development Regulations for the R-1 and R-2 Zoning Districts (eCode360) (San Bruno), quoted and re-checked
  13. Chapter 12.200: Development Regulations for the R-1 and R-2 Zoning Districts (eCode360) (San Bruno), quoted and re-checked
  14. Chapter 12.90: Accessory Dwelling Units and Junior Accessory Dwelling Units (eCode360) (San Bruno), quoted and re-checked
  15. Apply for a Permit, quoted and re-checked
  16. Chapter 12.200: Development Regulations for the R-1 and R-2 Zoning Districts (eCode360) (San Bruno), quoted and re-checked
  17. City of San Bruno Planning Division (sanbruno.ca.gov)
  18. San Mateo County Environmental Health Services (smcgov.org)
  19. Land Use, Septic & Wells, quoted and re-checked
  20. Land Use, Septic & Wells, quoted and re-checked
  21. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
  22. Chapter 12.270: Short-Term Residential Rentals (eCode360) (San Bruno), quoted and re-checked
  23. Typical home value (Zillow): Bolthole Index county data
  24. Effective property tax rate: 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 San Bruno

San Bruno’s own rules

  • Building permitRequired

    Accessory dwelling unit and junior ADU construction inside San Bruno city limits (general Title 11 permit rule for other construction not verified)

    • The permit is obtained after ministerial approval; construction may proceed only with the building permit.
    • A JADU also needs a signed, recorded deed restriction before its building permit (section 12.90.040).
    “upon finding that the adu or jadu meets the requirements of this chapter, the application shall be approved ministerially without discretionary review or public hearing and the applicant may proceed to acquire a building permit.”
  • Local zoningPresent

    Land inside San Bruno city limits, administered by San Bruno city under its own zoning ordinance (Title 12, Article III)

    • Chapter 12.96 establishes the zoning districts, including the R-1 single-family residential district at section 12.96.060.
    • Zoning-only topics for this jurisdiction are answered from this city ordinance, not from county zoning.
    “§ 12.96.060 r-1 single-family residential districts.”
  • Zoning districtsPublished

    Zoning districts inside San Bruno city limits

    • The Article III table of contents lists the R-1 through R-4 residential districts, C-N neighborhood commercial, A-R administrative and research, M-1 industrial, O open space and conservation, U unclassified, and P-D planned development districts (sections 12.96.060 through 12.96.190).
    • Chapter 12.200 covers the R-1 and R-2 districts; chapter 12.280 covers mixed-use districts and chapter 12.290 covers Bayhill specific plan districts.
    • No agricultural or rural-residential zoning district appears in the district list.
    “§ 12.96.080 r-3 medium density residential district. § 12.96.090 r-4 high density residential district.”
  • Minimum lot sizeDistrict specific (with conditions)

    Main single-family district, R-1 (and R-2, which shares chapter 12.200), inside San Bruno city limits. No agricultural or rural-residential district exists in the district list.

    • Minimum lot width is fifty feet, except sixty feet for corner lots (section 12.200.030(c)).
    • Legal substandard lots may qualify as building sites under the article's provisions (section 12.200.030(d)).
    • Chapter 12.200 applies to new structures and additions in the R-1 and R-2 districts.

    minimum site area, interior lot: >= 5000 sq ft · minimum site area, corner lot: >= 6000 sq ft

    “a. minimum site area. five thousand square feet for interior lots, six thousand square feet for corner lots.”
  • SetbacksDistrict specific (with conditions)

    Main single-family district, R-1 (and R-2), inside San Bruno city limits. No agricultural or rural-residential district exists in the district list.

    • Garage setback from sidewalk is twenty feet (section 12.200.030(d)(1)).
    • Where sixty percent or more of lots on a block are improved, the front yard is the average of improved lots if that average is less than the requirement.
    • On a legal substandard lot, the interior side setback may be reduced to ten percent of parcel width, but not below three feet; the street side setback may be reduced to five feet plus ten percent of parcel width, but not below eight feet.
    • Corner or through lots may, with an architectural review permit, reassign the front lot line (section 12.200.030(d)(5)).
    • Setback exceptions are set by section 12.84.170, which is not opened.
    • Side or rear encroachments up to two feet need an architectural review permit; larger encroachments need planning commission approval (section 12.200.040(a)).

    front setback: >= 15 ft (garage setback from sidewalk 20 ft) · interior side setback: >= 5 ft (legal substandard lots may be reduced) · street side setback (corner lot): >= 10 ft (legal substandard lots may be reduced) · rear setback: >= 10 ft

    “1. front: fifteen feet, except the minimum setback from sidewalk to a garage shall be twenty feet.”
  • Lot coverageDistrict specific (with conditions)

    Main single-family district, R-1, inside San Bruno city limits (R-2 has different limits)

    • Structure coverage is further limited by the permitted floor area, which is lot size times a floor-area ratio set by slope (section 12.200.030(g) through (i), charts 1 and 2).
    • Lot coverage over the percentage in section 12.200.030(e), up to 110 percent of allowed floor area, needs an architectural review permit; above that, planning commission approval (section 12.200.040(b)).
    • Impervious surface over the limit by ten percent or more needs planning commission approval (section 12.200.040(c)).

    structure coverage, R-1: <= 80 percent (of permitted floor area; R-2 is 100 percent) · impervious surface, R-1 total lot area: <= 80 percent (front setback area limited to 60 percent when a new dwelling is built or an addition increases floor area; R-2 is 85 percent)

    “maximum coverage by impervious surface - total lot area. eighty percent in the r-1 districts, and eighty-five percent in the r-2 district;”
  • Building heightDistrict specific (with conditions)

    Single-family R-1 and R-2 districts inside San Bruno city limits, measured under section 12.200.030(j)

    • Height is the vertical distance from the sidewalk elevation in front of the house at the midpoint of the house width to the topmost point of the roof, for purposes of chapter 12.200.
    • Slope classes: lots sloping side to side count as under 20 percent average slope; downsloping lots (front to rear) with 20 percent or more slope are limited to 26 feet; upsloping lots with 20 percent or more are limited to 30 feet.
    • Structures over the height limit by up to three feet need an architectural review permit; more than three feet needs planning commission approval (section 12.200.040(e)).
    • Second-story front decks, second-story windows facing side yards, and third stories are separately limited (section 12.200.030(k) through (m)).

    maximum height, lots under 20% average slope: <= 28 ft (also applies to lots sloping side yard to side yard) · maximum height, downsloping lots 20% or more: <= 26 ft (front to rear downslope) · maximum height, upsloping lots 20% or more: <= 30 ft (front to rear upslope)

    “1. a height of twenty-eight feet for lots with an average slope of less than twenty percent from front property line to rear property line”
  • Manufactured homesLimited

    Manufactured or moved-in homes placed on lots in the R-1 and R-2 districts inside San Bruno city limits

    • Such buildings are subject to the same requirements as new construction on infill lots, so the R-1 and R-2 dimensional and design standards apply.
    • Section 12.200.030 applies to the R-1 and R-2 districts only; other districts were not opened.
    “for the purposes of this section, buildings which are moved or manufactured off-site and placed on a property shall be subject to the same requirements as new construction on infill lots.”
  • Accessory dwellingsAllowed

    Accessory dwelling units and junior accessory dwelling units on residential lots inside San Bruno city limits (single-family and multifamily lots)

    • Review is ministerial: an ADU or JADU application is decided within sixty days of a complete application, without discretionary review or public hearing (section 12.90.040).
    • Setbacks: four feet minimum from side and rear lot lines, with no setback for conversion of existing space or of an existing accessory structure (section 12.90.050(e)(2)).
    • Height: 16 feet for a detached ADU on a lot with a single-family or single-story multifamily dwelling; 18 feet near major transit or on multi-story multifamily lots; attached ADUs follow the primary dwelling height (section 12.90.050(e)(7)).
    • One off-street parking space per ADU, with exceptions, including within one-half mile of public transit (section 12.90.050(e)(9)).
    • An ADU or JADU may not be rented for less than 30 days if permitted after January 1, 2020 (section 12.90.060(a)).
    • A JADU requires a recorded deed restriction barring separate sale (section 12.90.060(b)).
    • An ADU permitted after September 25, 2020 may not be used as a short-term rental (chapter 12.270).
    • No impact fees may be imposed on a JADU or ADU (section 12.90.080(c)).

    maximum floor area, studio or one-bedroom ADU: <= 850 sq ft (lots with a single-family dwelling, lots under 7,500 sq ft) · maximum floor area, ADU with more than one bedroom, lot under 7,500 sq ft: <= 1000 sq ft · maximum floor area, ADU with more than one bedroom, lot 7,500 sq ft or more: <= 1200 sq ft · detached ADU height, single-family lot: <= 16 ft (plus up to 2 ft to match a roof pitch) · ADU side and rear setback: >= 4 ft (no setback for conversions of existing space or structures)

    “a. zoning. accessory dwelling units shall be a permitted use in any district where residential uses are permitted.”
  • Mandatory utility hookupConditional

    Accessory dwelling units not within existing or proposed house space or an existing accessory structure, inside San Bruno city limits

    • A separate utility connection from the ADU to the utility is required, subject to a connection fee or capacity charge that may not exceed reasonable cost (section 12.90.080(b)).
    • ADUs created within the existing or proposed house space or an existing accessory structure need no new connection and no connection fee, unless built with a new house or conveyed separately (section 12.90.080(a)).
    “for an accessory dwelling unit not within the proposed space of a single-family dwelling or existing space of a single-family dwelling or accessory structure, a new or separate utility connection directly between the accessory dwelling unit and the utility is required.”
  • Short-term rentalsLimited

    Short-term residential rentals (stays under 30 consecutive days) of dwelling units inside San Bruno city limits

    • Non-hosted rentals of a whole unit are capped at 120 calendar days per calendar year, including ADUs legally built before September 25, 2020 where the primary home is owner-occupied (section 12.270.040(b)-(c)).
    • Hosted rentals have no annual day limit.
    • ADUs permitted after September 25, 2020 may not be used as short-term rentals.
    • Chapter 12.270 table of contents lists a required short-term residential rental zoning permit (12.270.050), with renewal every two years (12.270.060). Those sections were not opened.
    • Short-term rental uses outside section 12.270.040 are prohibited per the chapter text; the sentence was not captured in the opened excerpt.

    non-hosted whole-unit rental limit: <= 120 calendar days per calendar year (single-family, two-family, duplex or multiple-family unit) · hosted unit annual rental limit: no maximum

    “b. non-hosted units. an entire single-family dwelling unit, two-family or duplex dwelling unit or multiple-family dwelling unit may be utilized for short-term residential rental use subject to an annual usage limit of no more than one hundred twenty calendar days per calendar year.”
  • Permit processPartial

    Discretionary review for new structures, additions and certain changes in R-1 and R-2 districts inside San Bruno city limits; ADU and JADU applications are ministerial

    • Architectural review permits are decided by the community development director under chapter 12.108 for the listed project types; larger deviations go to the planning commission (section 12.200.040).
    • Architectural review permit procedure in chapter 12.108 was not opened.
    • ADU and JADU applications are decided ministerially (section 12.90.040).
    “upon finding that the adu or jadu meets the requirements of this chapter, the application shall be approved ministerially without discretionary review or public hearing and the applicant may proceed to acquire a building permit.”

Still unanswered

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

  • Owner-builder exemption — Owner-builder permit exemption inside San Bruno city limits
  • Building code adopted — Building code adoption inside San Bruno city limits
  • Inspections — Building inspections inside San Bruno city limits
  • Certificate of occupancy — Certificate of occupancy for new homes inside San Bruno city limits
  • Minimum dwelling size — Minimum dwelling size for a new home inside San Bruno city limits
13 more unanswered
  • Living in an RV
  • Camping on your land
  • Tiny homes
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Agricultural exemption
  • Subdividing land
  • Driveway access
  • Building in a floodplain
  • Permit fees

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 San Bruno publishes no rule on the point, not that none exists. San Mateo County’s page lists the county offices to call.

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