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Accessory Structures

How Santa Rosa Handles Accessory Structures: A Practical Guide

By CityRuleLookup Editorial Team

Santa Rosa maintains 47 local ordinances across all categories, and 4 of those deal specifically with accessory structures. Here is a breakdown of what the city actually requires, what is prohibited, and where Santa Rosa falls on the strict-to-permissive spectrum compared to other cities.

Carport Rules

Santa Rosa Zoning Code Section 20-42.030 caps carports at 16 feet tall and requires the carport face to sit at least 19 feet back from the property line, curb, or sidewalk on street-facing lots. Any structure over 120 sq ft needs a building permit. Carports are subject to Design Review and the 2022 California Building Code.

Key details: Code Section: Santa Rosa ZC 20-42.030. Max Height: 16 ft. Street Setback: 19 ft from line/curb. Alley Setback: 3-5 ft or 19+ ft. Permit Threshold: Over 120 sq ft.

Building a carport over 16 feet tall, inside the 19-foot street setback, in the prohibited 5-to-19-foot alley zone, or without a permit when over 120 sq ft can trigger stop-work orders, retroactive permitting fees, Design Review re-submittal, and required modification or removal under Santa Rosa Code Enforcement.

ADU Rules

Santa Rosa allows one ADU plus one JADU on single-family lots under Zoning Code Section 20-42.130, adopted by urgency Ordinance on March 3, 2020 to align with California Government Code Sections 65852.2 and 65852.22. Detached ADUs are capped at 1,200 sq ft with 4-ft side/rear setbacks and a 16-ft (one-story) or 27-ft (two-story) height limit; JADUs are capped at 500 sq ft and must sit entirely within the existing single-family dwelling walls.

Key details: Max detached ADU size: 1,200 sq ft habitable space. Max JADU size: 500 sq ft (+150 sq ft allowed for separate entrance). Side/rear setback (one-story): 4 ft minimum. Side/rear setback (two-story): 8 ft minimum. Height limit (one-story): 16 ft.

Construction of an ADU or JADU without a building permit constitutes a Santa Rosa Municipal Code violation enforced by Code Enforcement. The City offers an ADU Enforcement Deferral Program (Policy 2530) for certain unpermitted units built before March 3, 2020. Lack of compliance with JADU deed restrictions voids the JADU approval and may result in legal action against the property owner per Subsection G.3 of the ordinance.

Garage Conversions

Santa Rosa permits garage-to-ADU conversions ministerially under Zoning Code Section 20-42.130 with no replacement parking required and no setback required for existing legally constructed garages converted to an ADU with independent exterior access. Conversion to non-habitable storage requires a standard building permit, while conversion to habitable space (ADU or JADU) follows the city's 2020 ADU ordinance and California Government Code Sections 65852.2 and 65852.22.

Key details: Parking replacement required?: No (per E.10.h). Setback for converted existing garage: No setback required if converted to ADU with independent exterior access. Setback for ADU above existing garage: 5 ft from side and rear property lines. Max size of converted detached accessory structure ADU: 1,200 sq ft. Combined height (ADU over garage): 27 ft max.

Converting a garage to habitable use (kitchen, bathroom, sleeping space, conditioned living area) without a Building Permit and ADU/JADU approval under Section 20-42.130 is a code violation that may result in stop-work orders, demolition orders, and double permit fees. Unpermitted conversions are also subject to the ADU Enforcement Deferral Program (Policy 2530) only for units constructed before March 3, 2020; later unpermitted conversions face full enforcement.

Santa Rosa is more permissive than most cities when it comes to garage conversions. That said, there are still limits.

Shed Rules

Santa Rosa requires a building permit for any accessory structure over 120 square feet of floor area, per the city's Accessory Structure Requirements Policy (Policy No. 2.5.3, effective June 2, 2005, revised July 2011) which implements California Building Code Section 1808 and Santa Rosa Zoning Code Section 20-42.030. Sheds 120 sq ft or smaller are exempt from a structural permit but cannot be used as habitable or conditioned space, and any electrical or plumbing installation requires a separate permit.

Key details: Permit threshold: Building permit required for accessory structures over 120 sq ft. Sheds 120 sq ft or smaller: Building permit not required (electrical/plumbing still permitted separately). Allowed use: Storage only; habitable use or conditioned space prohibited. Foundation: Per CBC Table 1809.7 (light frame wood); pre-manufactured units per mfr specs. Max height: 16 ft and one story.

Constructing an accessory structure greater than 120 sq ft without a building permit, or using a permitted storage shed as habitable/conditioned space, is a Santa Rosa Municipal Code violation enforced by the Building and Code Compliance Division. Code Enforcement may issue stop-work orders, require demolition, or charge double permit fees for unpermitted construction. Habitable use of a storage shed also violates the recorded permit condition required under the Accessory Structure Policy.

The Bottom Line

Santa Rosa's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Santa Rosa is broadly strict or permissive.

These rules come from Santa Rosa's publicly available municipal code. For complete penalty schedules, exemption details, and answers to common questions, see the individual ordinance pages throughout this guide.