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

Yes. Mariposa County requires building permits for residential and commercial construction, including new construction, remodels, conversions, changes of occupancy, manufactured-home installation and grading¹. Limited exemptions include qualifying one-story detached accessory structures no larger than 120 square feet and fences no higher than 7 feet, but an accessory structure supplied with water or power still needs a building permit¹. A parcel with an existing code violation cannot move through a new permit or inspection unless the requested permit corrects that violation⁹. During construction, required inspections must occur before any part or system is covered; plans must be on site, and every other required agency must sign off before the final inspection¹⁰. An owner-builder may do the work but remains responsible for building permits, code compliance and inspections⁷. Permit fees vary by project, so request a project-specific estimate from the Building Department¹¹.

The Mariposa County Building Department issues building permits and enforces structural-safety laws at 5100 Bullion Street, Mariposa; call 209-966-3934 or email building@mariposacounty.gov⁹. The county processes development permits online, while the department's front counter can assist applicants who need help¹². For zoning and land-use questions, contact the Mariposa County Planning Department at the same street address by calling 209-966-5151 or emailing planningdept@mariposacounty.gov². Environmental Health reviews septic systems and wells at 5100 Bullion Street and can be reached at 209-966-2220 or eh@mariposacounty.gov¹³. Public Works Engineering handles county-road encroachments at 4639 Ben Hur Road, Mariposa, and can be reached at 209-966-5356¹⁴.

Yes. Mariposa County's Development Code is built around its zoning and subdivision ordinances, and a parcel's district, zoning map and applicable specific or area plan determine its permitted uses and standards^2,15. Outside adopted Town Specific Plan areas, new homes generally must sit at least 25 feet from property lines and 55 feet from the centerline of a public access road or easement; small parcels and state fire-safety rules can change the result, so give Planning the parcel number¹⁶. The listed county residential districts generally have a 35-foot height limit, though town-plan and overlay rules can add requirements¹⁷. ADUs and junior ADUs are allowed wherever residential or multifamily uses are allowed, follow state law and require a county building permit¹⁸. The county states no size constraint for second housing units, but health, safety and setback rules still apply; that does not answer minimum size for a primary home⁸. Vacation rentals and bed-and-breakfasts are permitted in most, but not all, zones and require a Transient Occupancy Tax certificate, an application and health-and-safety inspections¹⁹.

A new or repaired onsite septic system needs a permit before work begins, and a project that also requires a building permit must obtain the septic permit before or at the same time³. Environmental Health inspects, oversees and monitors septic systems; the County Health Department approves the system and the Building Department issues the installation permit^3,20. Site conditions deserve early attention because only 0.4% of Mariposa County soils are rated free of severe limitations for a conventional drain field²¹. Composting, incinerating and other non-discharge toilets are not substitutes for a fully sized septic or public sewer connection at a residence; their limited allowed uses require Health Department approval and a permit before installation³. For engineered or special systems, the registered professional who designs the system is responsible for design, inspection and certification, while the County Health Department still does a preapproval site evaluation and post-construction inspection³. Wells require a County Health Department permit before drilling, deepening, reconstructing or destroying begins, and the work must use a licensed C-57 contractor⁴.

Mariposa County treats travel trailers and RVs as substandard housing and does not allow them as residences unless the Building Department issues a permit in conjunction with an approved and issued single-family dwelling permit; licensed or authorized campgrounds and recreational facilities are outside that rule⁵. A structure marketed as a tiny home must be approved before occupancy as a recognized type, such as a code-built home, manufactured home, factory-built home, RV, park trailer or camping cabin⁶. The one RV exception is temporary housing, for up to five years, for residents who lost a home in the Oak Fire²². Manufactured homes on permanent foundations are permitted in countywide residential zones, subject to permits and any applicable historic-design standards²³. A mobile home made before January 1976 generally cannot be placed or relocated in Mariposa County unless it meets the applicable federal or state seal standard²⁴. Have Planning and Building classify the unit and confirm the parcel's zone before purchase^2,9.

1. Ask Planning to confirm the parcel's zoning district, residential use, setbacks, height limit and any town or area plan^15,16,17.
2. If adding an ADU or JADU, confirm state-law eligibility and the building-permit and deed-restriction steps¹⁸.
3. Resolve water and wastewater early: obtain Environmental Health review for septic and a county permit before well work begins^4,20.
4. Ask Public Works for an encroachment permit when access is from a county-maintained road²⁵.
5. Submit plans through the online Development Services Permit Center and request a project-specific fee estimate from Building^11,12.
6. Keep approved plans on site, request inspections before covering work, obtain every required agency signoff, and complete the final inspection for a certificate of occupancy¹⁰.

Start with buildability, not the listing description: confirm zoning, legal access, setbacks, water and septic feasibility before closing^3,4,15,25. For a proposed land division, Mariposa County requires adequate access, proof of water and parcel sizes set by the General Plan or applicable specific plan; septic testing, community-service and slope-stability requirements depend on acreage and site conditions²⁶. A house inside the Mariposa Public Utility District must contact that district for water and sewer hookup information²⁷. Terrain can materially affect site work because only 11.3% of Mariposa County land has a slope of 15% or less²¹. Conventional septic is another major constraint because only 0.4% of mapped soils avoid a severe drain-field limitation²¹. Water planning matters in a county averaging 31.4 inches of annual precipitation and experiencing severe drought in about 38.5% of recorded years²¹. Roughly 52.9% of the county is federal land, and population density is about 11.7 people per square mile, so verify practical year-round access and reachable services²¹. The effective property-tax rate is about 0.7%, with a median annual bill near $2,437²¹.