Fontana ADU Regulations

• ✓Tiered "Class 1 vs Class 2" ADU framework with different rules per class
• ✓Allows combined single-family stack: 1 JADU + 1 Class 1 + 1 conversion ADU
• ✓Standard ADU Plans (AB 1332) — Morning Glory, Carnation, Sunflower
• ✓Detailed multifamily ADU allowances including 25% conversion rule

Class 1 (state-regulated) ADU up to 800 sq ft / 16 ft. Class 2 detached new construction up to 1,200 sq ft and 16–18 ft height. Attached Class 2 per 50% primary or 850/1,000 sq ft thresholds. Conversions from existing space have no maximum size.

State guarantee: California requires every city to allow at least an 800 sq ft ADU exempt from local lot coverage, FAR, and front-setback rules.

Height baseline: 16 ft for detached, rising to 18 ft within ½ mile of major transit. Attached ADUs follow the primary home, capped at 25 ft.

Class 1 no parking required. Class 2 detached/attached generally 1 space with exemptions in §30-467. Conversions need no additional parking.

Build Fontana (Accela) portal for applications. Standard ADU Plans page lists AB 1332 pre-approved Morning Glory, Carnation, and Sunflower packages with designer contacts.

State backstop: A complete ADU permit must receive a decision in 60 business days. If the city stalls past 30 business days, AB 253 lets you hire a certified private plan checker to force a 10-business-day decision.

Building & Safety notes a 2.5% online processing fee on ACA/PayPal invoices effective Oct 1, 2025.

SB 543: No impact fees on ADUs ≤750 sq ft. Above 750 sq ft, fees scale to the ratio of ADU size vs the main home.

Visit the official Fontana ADU page (link in hero) for current eligibility and downloads.

Standard ADUs in Fontana: no owner-occupancy required (made permanent in 2023).

JADUs: limited to 500 sq ft of interior livable space within an existing single-family home. Owner occupancy is required only when sanitation facilities are shared with the main house. JADUs cannot be used as short-term rentals (AB 1154 / SB 543).