Building permits, zoning and septic rules in unincorporated Los Angeles County

Unincorporated Los Angeles County requires a permit before you build, add on, alter, move or demolish a structure, or work on its electrical, mechanical or plumbing systems¹. Like the counties around it in California, Los Angeles County requires a county building permit¹. The 2025 California Building Standards Code applies to buildings and structures with a permit application date on or after January 1, 2026¹⁰. The county adds amendments to the state code for Southern California construction concerns¹¹. Once a permit issues, request the first inspection within 12 months and schedule follow-up inspections every 6 months to keep it active¹. California's owner-builder exemption can remove the contractor-license requirement in qualifying cases, but it does not remove building permits or inspections¹².

Los Angeles County Public Works, Building and Safety Division, issues building permits for unincorporated communities through 10 district offices rather than one central counter⁴. Start with the county's online Service Locator and your street address or parcel number; it tells you which office handles your permit¹³. The division's headquarters is at 900 S. Fremont Avenue, 3rd Floor, in Alhambra, with the Building Plan Check line at (626) 458-3173⁴. Applications, plan uploads, fee payment and status tracking run through the county's EPIC-LA system¹³. The county's rules apply to unincorporated land. Inside Azusa, the city's own office handles building permits¹⁴; for other cities, confirm with the city before applying to the county. Septic permits stay with Public Health in every case⁵.

Unincorporated Los Angeles County is fully zoned: Title 22 applies to every property, use, building and structure outside the county's cities, and every parcel has a specific zone on file with LA County Planning^2,15. Cities set their own zoning, including Long Beach¹⁶, Pasadena¹⁷, West Covina¹⁸ and Azusa¹⁹; Title 22 does not apply there³. In the R-1 zone, the general minimum lot is 5,000 square feet, with a 20-foot front yard, 15-foot rear yard, 5-foot side yard and a 35-foot height limit; special districts can change those figures^2,9. The A-1 Light Agriculture zone also starts at 5,000 square feet, but animals, structures and uses add 1 to 5 acres²⁰. Single-family homes in R-1, A-1 and several other listed zones generally need at least 800 square feet of floor area². Confirm the parcel's zone and any Community Standards District with LA County Planning before buying^15,21.

Septic systems in unincorporated Los Angeles County are reviewed and approved by the Department of Public Health's Environmental Health division under its Local Agency Management Program, not by Public Works^22,23. Plan approval must come before any construction, installation, alteration or repair of an onsite wastewater system²⁴. For a new home or bedroom addition without public sewer within 200 feet, the dispersal area and a future replacement area must be designated and tested, with a feasibility report, plot plan and floor plan²⁵. The county will not approve a new septic system when a public sewer is available within 200 feet of the building²⁴. Public Health does site and installation inspections before final design approval, and that approval then goes to Building and Safety for the building permit²². Incomplete submittals are not accepted, and plan status is promised within 20 business days²⁵. Soils are a real constraint: only about 7% of county soils lack severe limitations for a conventional drain field, so non-conventional systems may be needed^25,26. Chemical toilets are limited to non-residential, short-term uses and are not a substitute for a septic system²⁴.

Living in an RV or trailer on private property in unincorporated Los Angeles County is generally not allowed for any length of time; the exceptions are disaster housing, a permitted RV park and the Interim and Supportive Housing Ordinance⁶. During a county-declared shelter crisis, one occupied RV may sit behind an owner-occupied single-family home on a lot of at least 5,000 square feet, rent-free, if it is operative, meets setbacks, stays at least 6 feet from buildings and ends occupancy within 30 days after the crisis expires⁷. Occupied RVs are not allowed on vacant lots⁷. Title 22 campgrounds are tent-camping uses that exclude permanent occupancy, and in the agricultural zones they need review such as a CUP in A-1². A certified double-wide manufactured home may serve as a single-family residence on a vacant parcel with county approval and an approved permanent foundation; a single-wide may qualify only as an ADU or temporary quarters during construction³. California treats a tiny home on a chassis with axles and 400 square feet or less of floor area as an RV, so the RV rule applies; a tiny home on a foundation must meet the building code^6,27. Ask LA County Planning to classify the unit before you buy²¹. Accessory dwellings are allowed with county review, and a junior ADU is capped at 500 square feet⁸.

1. Use the county's Service Locator with your address or parcel number to find which Building and Safety office serves the property¹³.
2. Confirm the parcel's zone, setbacks, height and any Community Standards District rules with LA County Planning before finalizing the site plan^15,21. Dividing land is a discretionary process: a tentative map goes to the County Subdivision Committee and a public hearing²⁸.
3. Apply through EPIC-LA and upload plans and required attachments¹³.
4. Budget separately for Planning filing fees, development-impact fees and Building and Safety permit fees; the published Planning schedule is not a complete construction-permit fee table²⁹.
5. Get septic plan approval from Public Health before any onsite-wastewater installation begins^23,24.
6. Once the building permit issues, request the first inspection within 12 months and keep follow-up inspections on a 6-month cadence until closeout¹.

Only about 31% of Los Angeles County land has a slope of 15% or less, so verify grading, road access and a feasible building pad for the parcel²⁶. Any driveway or access road meeting a public right-of-way must maintain sight distance acceptable to Public Works, and walls, fences, structures or storage near the property-line entrance may be reviewed³⁰. Public Works may also use its access guidelines when setting conditions for developments subject to discretionary approval or specified improvement requirements³¹. Severe drought has occurred in roughly 41% of years, so investigate a lawful water source²⁶. California requires a local permit before a water well is constructed, modified or destroyed³². In Los Angeles County, the Department of Public Health's Drinking Water Program reviews and approves wells, except in Long Beach, Pasadena and Vernon, which have their own environmental health departments³³. Dewatering or stabilizing wells for excavations and hillsides do not need a well permit³³. Flood Protection Districts regulate land Public Works identifies as subject to substantial flood hazard². After the Eaton Fire, a rebuild with added bedrooms on an existing cesspool must upgrade to septic or connect to sewer within 200 linear feet, subject to funding²². Short-term rentals are allowed only as an accessory use to a registered primary residence³⁴.