San Bernardino County ADU Permitting Process, Step by Step

Whether you're building in the City of San Bernardino, Fontana, Rancho Cucamonga, Ontario, Chino, Chino Hills, Redlands, or unincorporated San Bernardino County, the permitting process follows the same basic structure set by California state law (Government Code Section 65852.2), with each city's building department handling plan check and inspections locally.

Step 1: Pre-design research

Before drawing plans, confirm your lot's zoning, any easements, and whether you're working with an existing structure (garage conversion) or building new. Most cities and the county post ADU handouts or checklists on their planning department websites; a licensed contractor who regularly pulls ADU permits in your specific city can save you a research cycle by already knowing the local checklist.

Step 2: Plans and application submission

Your contractor or designer prepares construction plans (site plan, floor plan, elevations, and often a structural/energy compliance package) and submits them to the city or county building division along with the ADU application and fees. A complete, well-prepared submission is the single biggest factor in staying inside the 60-day state-mandated review window — incomplete packages get bounced back for corrections, which restarts the clock on those items.

Step 3: Plan check and ministerial review

Because ADUs that meet objective zoning standards (size, setbacks, height) are entitled to ministerial approval, staff review your plans against a checklist rather than sending them to a discretionary hearing or design review board. Expect one or more rounds of plan-check corrections for code items like fire separation, egress, or structural calculations — this is normal and not a sign your project is being rejected.

Step 4: Permit issuance and fees

Once plans are approved, you'll pay building permit fees (and, depending on the jurisdiction and unit size, potentially school and utility connection fees) before permits are issued and construction can begin. Some ADU size categories are eligible for reduced or waived impact fees under state law — ask your building department directly, since fee schedules vary by city.

Step 5: Construction and inspections

Your contractor schedules inspections at each major phase — foundation, framing, rough electrical/plumbing/mechanical, insulation, and final. Each city's building division sets its own inspection scheduling process (phone, online portal, or app), so confirm this with your contractor or the department before breaking ground.

Step 6: Final inspection and occupancy

After passing final inspection, the city or county issues a certificate of occupancy (or final sign-off) and the unit can legally be occupied or rented. At this point, many owners also update their property insurance and, if renting the unit, confirm any local rental registration requirements.

Because each city inside San Bernardino County runs its own plan-check queue and staffing levels, timelines can vary noticeably between, say, Fontana and Redlands even though both follow the same state law. A contractor who's actively pulling permits in your specific city right now is the best source for current, real-world timelines.