Walking Through the ADU Permit Process in San Bernardino County

ADUs are the best housing value in California right now if your lot supports one. State law has aggressively protected homeowner rights to build them, but San Bernardino County still has local specifics that trip people up. Here is the path from feasibility to final inspection.

Step one: lot and zoning check

Before you pay for plans, confirm your lot qualifies. State law permits one ADU plus one junior ADU on most single-family lots. We pull your parcel, check setbacks, and confirm lot coverage limits before you spend a dollar on design.

Step two: design and plan set

A complete plan set includes a site plan, floor plan, elevations, sections, and MEP. SB County wants to see exactly where the ADU sits, how far from property lines, and how utilities tie in.

Step three: submittal and plan check

Once submitted, plan check runs 60 to 90 days on average. SB County must review within state-mandated timelines. Expect a correction letter, handle it quickly, resubmit, and approval follows.

Step four: build

Foundation, framing, MEP, drywall, finishes, inspections at each milestone. A detached ADU typically runs 5 to 8 months from ground break to final.

Utility hookups

Depending on your water district, a separate meter may be required. Sewer connection usually taps into the existing lateral. Electrical can be sub-panel off the main or a full separate service.

Real timeline expectation

From first call to move-in ready, most detached ADUs run 9 to 14 months. Garage conversions run 4 to 7. If you need it faster, start now.

If you are exploring an ADU, see our ADU construction page and our comparison of home additions vs ADUs to help you pick the right path.