Building permits, zoning and land rules in Modoc County, California

Yes. In qualifying rural areas of unincorporated Modoc County, building permits are required for rural dwellings and related structures¹. "Rural" means unincorporated land zoned for minimum parcels of one acre or larger, subject to stated exceptions, and the application must include approval for private sewage disposal or another waste method¹. California law separately requires a building permit before any building or structure is erected, so a parcel outside the rural definition still needs one⁷. Modoc County adopted the 2022 California building codes in 2024¹⁵; the state's 2025 code applies to applications filed on or after January 1, 2026, so ask Building & Safety which edition governs your application¹⁶. A new rural dwelling receives at least 3 inspections: foundation, rough-in and final¹⁷. An owner-builder may qualify for a contractor-license exemption, but the project still needs the permit and inspections^11,18.

Modoc County Building & Safety handles building permits, plan review, inspections, code questions and permit records⁵. The office is at 203 West 4th St, Alturas, CA 96101, and its phone number is 530-233-6406⁵. The building-permit fee is computed from construction valuation, using code valuation data or documented actual cost, so no flat fee applies; ask for an estimate for your project¹⁹. Work must begin and receive an approved inspection within 365 calendar days after permit issuance, followed by the required annual inspection approvals¹⁹. Licensed contractors installing eligible rooftop solar on a permitted home can apply online through the county's SolarAPP+ portal, and inspections are scheduled by phone at (530) 233-6406; ground-mounted and ballasted systems do not qualify²⁰. For parcel zoning and allowable uses, call the Planning Department at the same number⁶.

Yes. Title 18 zoning regulates land in unincorporated Modoc County². Inside the city of Alturas, the city adopts its own zoning standards in Chapter 28 of its municipal code³. Planning gives parcel-specific guidance, because allowed uses, height, density and parking vary by zoning district^8,14. Minimum lot size, yards, setbacks and building coverage are district-specific²¹. The General Agricultural residential standards include a 40-acre minimum lot and 1% building coverage, but Planning should confirm the current standards for the parcel²¹. Dividing land is regulated too: Environmental Health reviews subdivisions, parcel boundary adjustments, divisions and combinations¹⁴. In the Flood Hazard zone, a building permit needs flood elevations, drainage information and findings that the project is reasonably safe from flooding²². A countywide minimum dwelling size and maximum building height could not be confirmed, so ask Planning before choosing a footprint⁶.

Modoc County Environmental Health regulates onsite wastewater systems throughout incorporated and unincorporated Modoc County, so Alturas addresses use the same septic office⁴. A septic permit is required before installing a new or replacement tank and leach field or repairing a failing system²³. The application needs a site plan, fee and soil-test data (repairs are excepted from the soil data), and Environmental Health must find the site suitable before issuing the permit; the permit lasts one year²³. The installer must request an inspection before the system is backfilled and submit an as-built plan; a single-family system may qualify for a waiver based on photographs⁴. Only 15.6% of county soils rate free of severe limitations for a conventional drain field, so make septic feasibility an early purchase contingency²⁴. All wastewater needs an approved treatment and dispersal method, including on off-grid parcels⁴. Environmental Health is at 202 West 4th Street, Alturas, California, phone 530-233-6310¹⁴.

Unincorporated Modoc County allows only occasional, temporary RV occupancy on a lot or parcel, and none in the I, IL and C zones⁹. In RR-4 through RR-15, LIC, RC, TP, AE and AG zones, occupancy may last up to 30 consecutive days or 90 calendar days in a year; RR-1 through RR-3, RH, RL and RT allow up to 30 days in a year⁹. In AE, AG, RC, LIC, TP and OFG zones, an administrative permit can allow up to 180 consecutive days in a year for a bona fide agricultural operation or resource-protection activity, with health-department compliance; the permit runs up to 5 years, and an extension beyond that needs a use permit⁹. Living in an RV while building a dwelling requires an administrative permit⁹. RV parks follow a separate limit of 6 months in a calendar year unless a use permit says otherwise⁹. An RV may not be occupied while parked on a public street or highway, and may be stored indefinitely if no one lives in it⁹. California allows a tiny home that qualifies as a manufactured, factory-built or code-built home, RV or park trailer, in a location approved for that type; Modoc County's own tiny-home rule could not be confirmed, so ask Planning how the unit will be classified^6,10. A manufactured home outside a licensed park needs an installation permit and generally must be no more than 10 years old when the application is filed¹².

1. Ask Planning to confirm the parcel's zoning, residential use, lot size, setbacks, coverage and any Flood Hazard-zone requirements^6,21,22.
2. Ask Environmental Health whether sewer is available or a septic site can be approved; submit the site plan, soil data and septic-permit fee before installation, and request the pre-cover inspection before backfilling^4,23.
3. Obtain the local well permit before constructing, altering or destroying a private well¹³.
4. Ask the Road Department about work in the county right-of-way; a state-highway connection requires a Caltrans encroachment permit^25,26.
5. Submit the building-permit application to Building & Safety and obtain the required approvals before construction; the fee depends on project valuation^1,19.
6. Request the required inspections and obtain the certificate of occupancy before moving in^1,17.

Confirm unincorporated Modoc County zoning before treating acreage as buildable because uses, lot size, setbacks and coverage are district-specific^8,21. Ask whether the parcel is in the Flood Hazard zone before designing the building, well or septic system²². Make septic feasibility a purchase contingency: only 15.6% of county soils rate free of severe limitations for a conventional drain field, and Environmental Health must approve the site^23,24. A private well also requires a local permit¹³. Modoc County averages 17.9 inches of precipitation and has experienced severe drought in 44.1% of years, so verify a reliable water plan²⁴. About 67.8% of the county is federal land, making boundaries, legal access and neighboring ownership worth checking²⁴. The effective property-tax rate is about 0.7%, with a median annual bill of about $1,445²⁴.