Contra Costa County, CA Accessory Structures: ADU Rental Restrictions (2026)
Key Facts
- Minimum rental term
- 30 days
- JADU resale
- Never separate from main house
- ADU resale
- Only per Gov. Code § 66341
- Enforcing agency
- Dept. of Conservation and Development
- Adopted
- Ord. No. 2025-07, May 13, 2025
Summary
Contra Costa County bars owners from renting an accessory dwelling unit or junior accessory dwelling unit for less than thirty days, closing off short-term rental use of ADUs built under Ordinance Code Chapter 82-24. A junior ADU can never be sold apart from the main house, and a full ADU can only be sold separately if state law under Government Code Section 66341 allows it.
(a)No accessory dwelling unit or junior accessory dwelling unit may be rented or offered for rent for a term of less than thirty days.(b)A junior accessory dwelling unit may not be sold separately from the primary single-family dwelling.(c)An accessory dwelling unit may not be sold separately, except in conformance with Government Code section 66341.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Ordinance Code: Supplement 103).
Full Breakdown
Contra Costa County's Accessory Dwelling Unit chapter, recodified in full by Ordinance No. 014, "Occupancy and sale restrictions," locks down how those units can be used once built. Subsection (a) prohibits renting or offering to rent any ADU or JADU for a term under thirty days, so unincorporated county homeowners cannot list a backyard cottage or garage conversion on a nightly or weekly booking platform. Subsection (b) bars selling a JADU separately from the primary single-family home entirely, since JADUs share utility connections and cannot be subdivided off.
Subsection (c) extends the same no-separate-sale rule to full ADUs, unless a sale is structured to comply with Government Code Section 66341, the state provision allowing limited ADU condominiumization. " The Department of Conservation and Development administers ADU permits and holds the recorded restriction; a buyer who ignores the disclosure still takes the property subject to it because the restriction runs with the land, not with any particular owner.
Violations & Fines
Renting an ADU or JADU short-term, or selling a JADU apart from the main house, breaches the deed restriction and permit conditions under Section 82-24.014. Because the restriction is recorded against the property, the Department of Conservation and Development can pursue code enforcement against the current owner directly, and a JADU permit obtained through a false or later-violated disclosure statement is subject to revocation under the county's general permit enforcement authority.
Frequently Asked Questions
Can I rent out my Contra Costa County ADU on Airbnb?
Can I sell my junior ADU separately from my house?
Does the thirty-day rule apply to a full detached ADU too?
Sources & Official References
Other rules in Contra Costa County
California rules heatmap·Compare Contra Costa County to another location·View the California accessory structures overview
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