Bolthole Index

San Mateo County, California

Zoning, building permits and septic rules in Redwood City, California

Redwood City, California adopts its own zoning code for land inside city limits1, and requires a city building permit before a building is moved onto a lot2. Living in a trailer is unlawful outside a trailer park3. Septic and well permits come from San Mateo County Environmental Health45, not the city.

At a glance

Zoning
Redwood City adopts its own zoning code inside city limits1
Building permit
Required to move a building onto a lot; the general new-construction rule was not confirmed2
Living in an RV or trailer
Unlawful except in a trailer park3
Manufactured homes
Allowed on single-family lots on a permanent foundation6
Minimum lot size
Set by district: 10,000 sq ft in RH, 6,000 sq ft in R-17
Septic
San Mateo County Environmental Health permits individual sewage disposal systems4
Owner-builder
State licensing exemption only; it does not remove the permit requirement8

Who to call

Septic permits

San Mateo County Environmental Health Services

Septic (OWTS) permits, site evaluations 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 16, 2026.

Off-grid gear

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

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Does Redwood City have zoning, and what does it mean for RVs, tiny homes and lot size?

Redwood City adopts and enforces its own zoning code for land inside city limits1. Lot-size minimums vary by district: the minimum lot area is 10,000 square feet in RH and 6,000 square feet in R-17, and 5,000 square feet in R-29. Main buildings in R-2 must sit at least 15 feet back from the front property line and 20 feet from the rear line10.

Manufactured homes are permitted on lots zoned for single-family use when installed on a permanent foundation, under the same development standards as conventional houses6. Redwood City's code makes it unlawful to live or sleep in a trailer unless it sits in a trailer park or serves as a construction-site office3. We could not confirm a Redwood City rule for tiny homes; ask the city's Planning Division.

Do you need a building permit in Redwood City, and who issues it?

Inside Redwood City, the city, not San Mateo County, handles building permits; the county's building permit rules cover unincorporated land only11. Redwood City's code requires the owner of a lot to secure a building permit before a building is moved to it2. We could not confirm the city's general new-construction permit rules, fees or inspection steps, so contact the City of Redwood City Building Division before you plan work.

California's owner-builder exemption covers contractor licensing only; the owner-builder who signs the permit application still needs the permit and inspections12.

Can you live in an RV or trailer in Redwood City?

Not on an ordinary lot. Redwood City's zoning code makes it unlawful to occupy a trailer for living or sleeping unless the trailer is in a trailer park or serves as a construction, circus or carnival office3. Parking is also restricted: recreational vehicles may not be parked on a public street, alley or city-owned lot from 8:00 PM to 5:00 AM, and violators face citation, towing or both13. Where a lot lies in a mapped flood zone, RVs must be on site fewer than 180 consecutive days or be fully licensed and ready for highway use14.

How do septic permits work in Redwood City?

Redwood City does not issue septic permits in the records we reviewed; we could not confirm who permits septic systems inside city limits. San Mateo County requires a permit from Environmental Health for anyone installing an individual sewage disposal system4, and county staff observe and approve installation, repair and destruction15. California requires a permit for every new or replacement septic system16. Water wells also need a drilling permit from Environmental Health Services5. Call Environmental Health at (650) 372-620017 to confirm whether a specific address is on sewer or needs a septic system.

Building a home in Redwood City: the steps, in order

  1. Confirm the lot's zoning district and minimum lot size with the City of Redwood City Planning Division1.
  2. Check whether the lot lies in a special flood hazard zone, which adds permit and elevation requirements14.
  3. Apply for a building permit with the City Building Division; we could not confirm the city's full application steps.
  4. Contact San Mateo County Environmental Health for septic or well permits if the lot is not on sewer or city water4.
  5. Finish inspections before you occupy the building.

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

San Mateo County Environmental Health runs septic oversight under its local program18, and the county's own building and zoning counters serve unincorporated land only11. For land outside city limits, see the San Mateo County page. County-level figures: the median property tax bill is $9,167 a year19 and a typical home is valued at about $1,595,76420. Splitting a lot is regulated; Redwood City limits urban lot splits to no more than two new lots21.

Watch-outs

  • Redwood City's general building permit rules were not confirmed; its code confirms a permit only for moving a building onto a lot2.
  • San Mateo County's building and zoning counters serve unincorporated land only, so inside Redwood City they are the wrong office11.
  • Redwood City bars living in a trailer outside a trailer park, so an RV is not a place to stay while you build3.

Sources

  1. Zoning Code 6.1 Purpose (R-2) (Redwood City), quoted and re-checked
  2. City Code 9.30 Building permit required (moved buildings) (Redwood City), quoted and re-checked
  3. Zoning Code 31.13 Mobile Homes and Trailers (Redwood City), quoted and re-checked
  4. Land Use, Septic & Wells, quoted and re-checked
  5. Land Use, Septic & Wells, quoted and re-checked
  6. Zoning Code 31.13 Mobile Homes and Trailers (Redwood City), quoted and re-checked
  7. Zoning Code 5.3 Lot Area (RH, R-1) (Redwood City), quoted and re-checked
  8. Owner-Builder Overview, quoted and re-checked
  9. Zoning Code 6.4 Minimum Lot Size (R-2) (Redwood City), quoted and re-checked
  10. Zoning Code 6.7 Setbacks (R-2) (Redwood City), quoted and re-checked
  11. Apply for a Permit (2026 county census)
  12. Owner-Builder Responsibilities (California statewide rule), quoted and re-checked
  13. City Code 20.101.5 Parking of recreational vehicles prohibited (Redwood City), quoted and re-checked
  14. City Code 41.22 Standards for recreational vehicles (floodplain) (Redwood City), quoted and re-checked
  15. Land Use, Septic & Wells, quoted and re-checked
  16. 2023 OWTS Policy (California statewide rule), quoted and re-checked
  17. San Mateo County Environmental Health Services (smcgov.org)
  18. Land Use, Septic & Wells, quoted and re-checked
  19. Median property tax bill: Bolthole Index county data
  20. Typical home value (Zillow): Bolthole Index county data
  21. City Code 30.75 Urban lot splits definitions (Redwood City), quoted and re-checked

Written October 16, 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 Redwood City

Redwood City’s own rules

  • Building permitRequired

    Moving a building to a site inside Redwood City; general permit rule not otherwise opened

    • Section quoted covers moved buildings; general new-construction permit text not opened
    “No building shall be moved to any site within the City until the owner of the lot or parcel to which the building is to be moved, or their agent, secures a building permit”
  • Local zoningPresent

    Land inside Redwood City city limits

    “This district is intended for small and medium scale residential densities as permitted in the General Plan.”
  • Minimum lot sizeSpecified

    R-2 (Residential-Duplex) district inside Redwood City

    • Minimum frontage 35 feet and average width 50 feet
    • Sloping-lot subdivision requirements in Section 32.2

    R-2 minimum lot size: >= 5000 sq ft · minimum frontage: >= 35 ft · minimum average width: >= 50 ft

    “a. the minimum lot size is five thousand (5,000) square feet. b. the minimum lot frontage is thirty-five (35) feet. c. the minimum average lot width is fifty (50) feet.”
    One more reviewed finding on this topic
    • Specified — RH (Residential-Hillside) and R-1 (Residential-Single-Family) districts inside Redwood City
      “the minimum lot area requirement is ten thousand (10,000) square feet for the rh zoning district and six thousand (6,000) square feet for the r-1 zoning district, with exceptions to these requirements described in subsections b, c, and d.”
  • SetbacksSpecified

    Main buildings in the R-2 (Residential-Duplex) district inside Redwood City

    • Carport entrances and garage doors 20 ft from front line
    • One-story interior side setback 10% of lot width, min 4 ft, max 6 ft
    • Corner street-side 25% of lot width, min 12.5 ft, max 15 ft
    • See Section 32.3 for two-story and modifications

    front setback: >= 15 ft · rear setback: >= 20 ft

    “structures must be set back a minimum of fifteen (15) feet from the front property line; carport entrances and garage doors must be set back a minimum of twenty (20) feet.”
  • Living in an RVLimited

    Living or sleeping in a trailer inside Redwood City

    • Unlawful to occupy a trailer for living or sleeping unless located in a trailer park or used as an office for a construction project, circus, or carnival while those activities are conducted
    • No trailer or mobile home parked in a public right-of-way or blocking a required parking space for more than 48 hours

    trailer parking limit in right-of-way: <= 48 hours

    “it shall be unlawful for any person to occupy or use any trailer for living or sleeping purposes unless such trailer is either located in a trailer park or is being used as an office for a construction project, a circus, or carnival, while such activities are being conducted.”
  • Camping on your landLimited

    RV parking on public streets and city lots inside Redwood City overnight

    • Prohibited 8:00 PM to 5:00 AM on public street, alley, highway or city lot
    • Exemptions include 48 hours in 7 days in front of owner's dwelling for loading/unloading, event permits, and Temporary RV Safe Parking Program permits
    • Violators subject to citation, towing, or both
    “no person shall park, stop, or leave standing any recreational vehicle upon a public street, alley, or highway within the City or a parking lot owned or leased by the city between the hours of eight o'clock (8:00) p.m. and five o'clock (5:00) a.m. of any day, except as provided within subsection c of this section. violators will be subject to citation, towing, or both.”
  • Manufactured homesLimited

    Manufactured homes inside Redwood City

    • Must be installed on a permanent foundation in compliance with the California Health and Safety Code and Government Code Section 65852.3
    • Permitted on lots zoned single-family residential subject to the same development standards as conventional single-family dwellings
    • Mobile homes otherwise only in a mobile home park
    “this section shall not apply to a manufactured home installed on a permanent foundation in compliance with the california health and safety code and government code section 65852.3, and such manufactured homes shall be permitted on lots zoned for single-family residential use subject to the same development standards applicable to conventional single-family dwellings in the same zone.”
  • Subdividing landRegulated (with conditions)

    Subdivision of land inside Redwood City (City Code Chapter 30)

    • Urban lot splits limited to no more than two new lots meeting Article XII criteria and Government Code Section 66411.7
    • Applicable Engineering Standards apply
    “article xii. - urban lot splits sec. 30.75. - definitions:”
  • Building in a floodplainRequired

    Development in special flood hazard zones inside Redwood City (City Code Chapter 41)

    • RVs in Zones A1-30, AH, AE, V1-30 and VE must be on site fewer than 180 consecutive days, be fully licensed and highway-ready, or meet permit and elevation requirements of Sections 41.16 and 41.20
    “all recreational vehicles placed in zones a1-30, ah, ae, v1-30 and ve will either: 1. be on the site for fewer than one hundred eighty (180) consecutive days; or 2. be fully licensed and ready for highway use.”

Still unanswered

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

  • Owner-builder exemption — Inside Redwood City
  • Inspections — Inside Redwood City
  • Certificate of occupancy — Inside Redwood City
  • Minimum dwelling size — Inside Redwood City
  • Lot coverage — Inside Redwood City
13 more unanswered
  • Building height
  • Tiny homes
  • Who permits septic
  • Septic permit
  • Septic inspection
  • Off-grid sanitation
  • Well permit
  • Mandatory utility hookup
  • Agricultural exemption
  • Driveway access
  • 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 Redwood City 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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