ADU Laws & Regulations in San Bernardino County 2026 – What You Need to Know

San Bernardino County is one of the most ADU-friendly areas in Southern California, thanks to state laws (AB 68, AB 881, SB 13, and updates through 2026) that encourage accessory dwelling units to address housing shortages. Whether you're in San Bernardino city, Fontana, Ontario, Rancho Cucamonga, Victorville, or a rural area, ADUs are easier to build than ever.

But rules still vary by city and county, and missing something (like Title 24 energy compliance or setbacks) can delay your project months. Here's a clear, up-to-date overview of ADU laws in San Bernardino County for 2026.

1. Key State & County ADU Laws in 2026

• Size Limits: Up to 1,200 sq ft for detached ADUs (or 50% of primary home size, whichever is larger). Attached ADUs can be up to 1,200 sq ft.

• Number Allowed: One ADU + one JADU (Junior ADU) per lot (state law).

• No Owner Occupancy Required: You don’t have to live in the primary home (state law change 2020+).

• No Parking Minimums: No extra parking required for ADUs if within 0.5 miles of transit or in low-vehicle travel areas (most of San Bernardino County qualifies).

• Setbacks: 4 ft side/rear minimum, no front setback if attached to house. Height up to 16–18 ft (varies by zone).

• Lot Size: No minimum lot size for ADUs (state preemption).

• Fire Safety: Garage separation (1-hour rated walls, self-closing doors), tempered glazing, smoke/CO detectors, and sprinkler requirements if applicable.

• Title 24 Energy Compliance: Mandatory for all ADUs — solar-ready, efficient lighting/HVAC, insulation (R-30 ceiling, R-21 walls typical).

2. Local San Bernardino County Rules (2026)

• Zoning: Most residential zones (R-1, R-2, R-3, etc.) allow ADUs. Check your parcel on the County Zoning Map or call Planning (909-387-8311).

• Permitting: Electronic submittal via Riverside County-like portal (San Bernardino uses Accela). Typical review 60–90 days if plans are accurate.

• Fees: $5,000–$15,000 (plan check, building permit, impact fees). Lower than coastal counties.

• Common Issues: Missing Title 24 report, inadequate dryer vent routing, garage separation details, or future EV/ESS readiness notes.

• No HOA Block: State law prevents HOAs from banning ADUs (SB 13).

3. City-Specific Variations in San Bernardino County

• Fontana, Ontario, Rancho Cucamonga: Faster approvals (60–80 days), lower fees, garage conversions popular.

• Victorville, Hesperia: More rural — fewer setbacks, but longer utility runs can add cost.

• San Bernardino City: Slightly stricter on parking in some zones, but state preemption applies.

4. How to Comply & Avoid Delays

• Work with local drafters like Michael's Drafting — we know San Bernardino County plan checker comments and Title 24 requirements.

• Get Title 24 energy report early (required for all ADUs).

• Include garage separation details (1-hour walls, self-closing doors) if converting.

• Submit accurate plans first time — resubmissions add 30–60 days.

• Budget 10–20% contingency for fees/corrections.

ADU laws in San Bernardino County 2026 make it one of the easiest places in Southern California to build. No parking minimums, larger size limits, and faster approvals mean more homeowners are adding units for rental income or family space.

Ready to build your ADU? Contact Michael's Drafting for permit-ready plans, Title 24 compliance, and expert guidance in San Bernardino County and all Southern California. Free consultation – call 909-486-3789 or email info@michaelsdrafting.com today.