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

Yes. Unincorporated Merced County generally requires a building permit for new construction, remodels, additions, alterations, repairs, improvements, conversions of use, electrical, plumbing, mechanical work, and demolition¹. Limited exceptions generally involve minor repairs, but exempt building work may still need electrical, plumbing or mechanical permits and remains subject to other laws¹. One narrow agricultural example is an awning attached to and entirely supported by exterior walls that projects no more than 54 inches; this is not a blanket agricultural-building exemption^1,12. The county ordinance adopts the 2022 California Building and Residential Codes, with local amendments for soils investigation and continuous footing reinforcement, while California's 2025 Building Standards Code applies to permit applications dated on or after January 1, 2026^13,14. Starting permit-required work without a permit triggers an investigation fee of 1 times the normal permit fee, rising to 5 times for a fifth occurrence within five years¹³. Before occupancy or use, the project must pass final inspection and receive a certificate of occupancy^1,15. The owner-builder option affects contractor licensing, not county permits or inspections¹⁶.

The Building and Safety Division issues building permits and inspects construction in unincorporated Merced County, at 2222 M St., 2nd Floor, Merced, CA 95340, phone (209) 385-7477¹⁵. Inside the city of Atwater, the city issues its own building permits, so the county counter is the wrong office there¹⁷. The county accepts building-permit applications and corrections electronically¹⁵. The published sequence is permit application, plan check, permit issuance and inspections, with zoning approval first; a Conditional Use Permit, Administrative Permit or Plot Plan Approval may be needed before the building permit¹. Initial plan check takes 4 to 6 weeks when plans and documents are complete and plan-check fees are paid¹. Request an inspection before 4:00 p.m. on the preceding business day, and keep the permit card and job-copy plans at the site; a $77 reinspection fee may be assessed if the job is not ready or accessible¹⁵. Separate Planning, Roads, Environmental Health and Fire plan-check fees may apply, while the local school district sets its own impact fee¹. Septic permits stay with the county Division of Environmental Health¹⁸.

Yes. Merced County's Zoning Code applies to all land uses, structures, subdivisions and development in the unincorporated area². Inside Merced and Atwater, each city's own zoning ordinance applies instead^3,4. Like the counties around it in California, Merced County has county zoning⁶. The county's interactive map viewer identifies a parcel's zoning by address or parcel number, and district standards vary by zone and special-plan area⁶. Minimum sizes for newly created parcels vary sharply: an R-R parcel without public sewer or water needs at least 1 net acre, while an R-1 interior parcel can be 6,000 square feet⁹. Newly created agricultural parcels require at least 20 acres in A-1, 40 acres in A-1-40 and 160 acres in A-2¹⁹. Structures may cover at most 40% of an R-R lot without public sewer or water, and 60% with it¹⁹. Numeric setbacks are not published in the sources we reviewed; the Planning Division can confirm them for a parcel, and they are checked during building plan check^20,21.

Merced County's Division of Environmental Health administers onsite wastewater treatment systems under County Code Chapter 9.54⁵. Repairing an existing septic system or constructing a new one requires county approval and a construction permit, which remains valid for 6 months after approval⁷. Every gallon of wastewater generated on the property must be treated by an approved septic tank-leach field system, and departing from the approved design may require another permit²². Parcels in county-established Zones of Benefit, including subdivisions in the Lake Yosemite area, receive annual inspections of the leach field, diversion valve and septic tank⁷. Only 4.6% of Merced County soils rate free of severe limitations for a conventional drain field, so obtain the county's site evaluation before treating a standard system as feasible²³. Reach Environmental Health at 2222 M St., Merced, CA 95340, phone (209) 381-1100¹⁸.

During approved construction, yes, temporarily: the County Director may issue a Temporary Use Permit letting you live on-site in a conventional, mobile, or recreational-vehicle temporary dwelling while a new or remodeled home is being built, but that temporary residence must be removed within 120 days after final inspection or occupancy of the finished home, whichever comes first⁸. Outside of that construction window, California treats RVs as not intended for permanent occupancy, generally allowed only in mobilehome parks or special occupancy parks unless a local ordinance says otherwise, and we could not confirm a Merced County ordinance allowing routine RV living on a private rural parcel²⁴. A tiny home not on a permanent foundation is only a permitted use in the M-H Single-Family Mobile Home Residential Zone, an urban-community zone with public water and sewer; outside that zone, statewide rules require a tiny home to qualify and be approved as a HUD-code manufactured home, a Building Code-compliant home, factory-built housing, an RV, a park trailer, or a camping cabin to be legally occupied^9,24. A manufactured home fares better in ordinary residential zones, but only on a permanent foundation meeting the county's standards, including a minimum roof pitch of two inches of vertical rise per 12 inches of horizontal run and a minimum 12-inch eave projection on all sides⁸.

1. Look up the parcel's zoning district and confirm its allowed use, lot size and setbacks with the Planning Division^6,20.
2. If the site is not on public sewer, apply to the Division of Environmental Health for a septic construction permit, which remains valid for 6 months after approval^5,7.
3. For a new driveway onto a county-maintained road, obtain Road Division approval through an encroachment permit or approved improvement plans; access location and width depend on road class and parcel conditions²⁵; a residential driveway serving fewer than three units must be at least 14 feet wide on local roads and 18 feet on collector or minor arterial roads²⁵.
4. Submit the building-permit application and corrections electronically to Building and Safety after any required land-use approval^1,15.
5. Request inspections before 4:00 p.m. on the preceding business day and keep the permit card and job-copy plans on site¹⁵. If the project is in a flood zone, provide an Elevation Certificate at forms inspection and again at final inspection¹.
6. Pass final inspection and obtain the certificate of occupancy before moving in¹.

Confirm the parcel's zoning district, allowed use, lot size and setbacks because each district and special-plan area can differ^6,20. Obtain a soil evaluation before counting on conventional septic: only 4.6% of Merced County soils rate free of severe drain-field limitations, and Environmental Health must approve the system^5,23. For groundwater de minimis, replacement, backup and new wells—and the other listed construction, reconstruction, destruction, mining or export proposals—the county requires an Environmental Health application and permit¹⁰. A new driveway onto a county-maintained road needs Road Division approval, either an encroachment permit or approved Improvement Plans²⁵. Splitting a parcel is a separate process: subdivisions must follow the California Subdivision Map Act and County Code Title 17²⁰. A driveway within a state highway right-of-way instead requires a Caltrans encroachment permit²⁶. Development in a mapped special flood-hazard area requires a development permit before work begins, and inspected flood-zone construction requires Elevation Certificates during the inspection sequence^1,27.