Sonoma, CA Accessory Structures: Garage Conversions (2026)
Garage conversion rules in Sonoma, CA, sometimes called garage-to-ADU or accessory living unit conversions, govern permits, ceiling height, egress, and parking replacement.
Key Facts
- Governing section
- SMC 19.41.150(A)(8)(d)
- Applies to
- Two-unit (SB 9) residential development only
- Replacement parking
- At least 1 space per unit, covered or uncovered
- Tandem parking
- Prohibited under 19.41.150(A)(8)(c)
- Transit exemption
- Waived within 1/2 mile of major transit stop
- Denial authority
- City director may deny under SMC 19.41.160
Summary
When a City of Sonoma property owner converts or demolishes an existing garage, carport, or covered parking structure to build a second unit under the city's SB 9 two-unit residential program, SMC 19.41.150(A)(8)(d) requires at least one replacement parking space, covered or uncovered, for each unit.
8. Off-Street Parking. ... a. One covered or uncovered off-street parking space is required per dwelling unit in a two-unit residential project, except as exempted below. ... ... c. Tandem parking is prohibited. Each unit must have its own parking space which can be accessed without crossing over or encroaching upon the other unit’s parking space. d. When an existing garage, carport, or other covered parking structure is converted or demolished in order to construct a new unit, at least one replacement parking space, which may be covered or uncovered, must be provided for each unit, unless the project is exempt from parking requirements.
Official source re-checked September 8, 2026: no newer edition of the code had been published (publisher’s edition: current through Ordinance 13-2025, passed December 3, 2025).
Full Breakdown
7) for two-unit residential development and urban lot splits; it governs garage conversions specifically in that two-unit context rather than accessory structures generally. 150(A)(8) sets the baseline: one covered or uncovered off-street parking space is required per dwelling unit in a two-unit project. Subsection (8)(c) bars tandem parking, requiring each unit to have its own space reachable without crossing the other unit's space. Subsection (8)(d) is the garage-conversion trigger: when an existing garage, carport, or other covered parking structure is converted or demolished to make way for a new unit, the property owner must provide at least one replacement parking space, which does not have to be covered, for each unit, unless the project is exempt from parking requirements altogether.
150(A)(8)(a)(i) waives parking entirely for a parcel within a half-mile walk of a high-quality transit corridor or major transit stop, or within one block of a designated car-share space, tracking the state parking exemptions built into SB 9 and the Density Bonus Law. 150(A) says any such standard is waived to the extent it would block that minimum development.
Violations & Fines
A two-unit project that converts or demolishes covered parking without providing the replacement space required by SMC 19.41.150(A)(8)(d), where no transit or car-share exemption applies, does not meet the objective standards for ministerial approval and can be denied under SMC 19.41.160; a project built without required replacement parking is separately enforceable as a public nuisance and misdemeanor under SMC 19.90.040 and 19.41.170.
Frequently Asked Questions
If I convert my garage to build a second unit in Sonoma, do I have to replace the parking?
Does the garage replacement parking rule apply to any accessory structure conversion?
Is there any way to avoid the replacement parking requirement?
Sources & Official References
Other rules in Sonoma
California rules heatmap·Compare Sonoma to another location·View the California accessory structures overview
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Garage Conversions in Nearby Cities
How other cities in Sonoma County handle garage conversions.