ADU Rules: Vacaville vs Vallejo
How do adu rules rules compare between Vacaville, CA and Vallejo, CA?
Vallejo has fewer restrictions than Vacaville.
Vacaville, CA
Solano County
Vacaville permits ADUs and JADUs ministerially under VMC 14.09.122 in conformance with California Government Code 66310 et seq. (renumbered from 65852.2 effective 2024). ADU maximum size scales with the primary dwelling: 850 sq ft if primary is up to 1,700 sq ft, 1,000 sq ft if primary is up to 2,000 sq ft, and 1,200 sq ft (or 50% of primary if larger) otherwise. ADUs cannot be used for short-term rentals under 31 days.
View full Vacaville rules →Vallejo, CA
Solano County
Vallejo regulates ADUs and JADUs under Vallejo Municipal Code Chapter 16.303 (Accessory Dwelling Units). Detached ADUs are capped at 1,200 sq ft, attached ADUs at 1,200 sq ft or 50% of the primary dwelling (whichever is less), and JADUs at 500 sq ft within the existing single-family structure.
View full Vallejo rules →Key Facts Comparison
| Fact | Vacaville | Vallejo |
|---|---|---|
| Code Section | VMC 14.09.122 / Gov. Code 66310 | VMC Ch. 16.303 |
| Review Type | Ministerial (no hearing) | - |
| Max Size (1700 sf primary) | 850 sq ft ADU | - |
| Max Size (2400+ sf primary) | 1,200 sq ft or 50% of primary | - |
| Owner Occupancy | Required if permitted 2025+ | - |
| Min STR Term | 31 days | - |
| Max Detached ADU | - | 1,200 sq ft |
| Max JADU | - | 500 sq ft |
| Detached Height | - | 16 ft |
| Side/Rear Setback | - | 4 ft minimum |
Highlighted rows indicate differences between cities.
Vacaville FAQ
How big can my Vacaville ADU be?
Up to 850 sq ft if your primary home is 1,700 sq ft or less, up to 1,000 sq ft if primary is up to 2,000 sq ft, up to 1,200 sq ft if primary is up to 2,400 sq ft, and up to 50% of primary (capped at 1,200 sq ft) for larger primary dwellings. State law (Gov. Code 66323) guarantees at least 800 sq ft regardless.
Does Vacaville require owner-occupancy for an ADU?
Yes for ADUs permitted on or after January 1, 2025. Government Code 66332(a) (reinstated by SB 477 in 2024) allows local owner-occupancy rules for post-2025 permits, and Vacaville's amended ordinance imposes one. Pre-2025 permits remain governed by the prior preemption (no owner-occupancy required). JADUs always require owner-occupancy under Gov. Code 66333.
Vallejo FAQ
How big can my Vallejo ADU be?
Under VMC Chapter 16.303, detached ADUs are capped at 1,200 sq ft and attached ADUs at 1,200 sq ft or 50% of the primary dwelling, whichever is less. JADUs are capped at 500 sq ft.
How long does it take to get a Vallejo ADU permit?
Vallejo issues a ministerial decision on a complete ADU application within 60 days, per VMC Chapter 16.303 and California Government Code §65852.2.
Can I rent my Vallejo ADU on Airbnb?
No. The recorded deed restriction required under VMC Chapter 16.303 prohibits short-term rental use. ADU rentals must be for 30 days or longer.
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