Marin County

Sausalito ADU rules

Research summary of local ADU rules on file for Sausalito in Marin County. Not a determination for a specific lot.

Last checked October 26, 2026.

City or county ADU page

Sausalito rules on file

Local rules recorded in this project for this jurisdiction. Where a city figure on file is stricter than the state baseline on file, both are shown.

Which rules apply
Sausalito's ADU rules are in Municipal Code Section 10.44.080 (last amended by Ordinance 12-2025, December 2, 2025). Its one-story limit and its historic-district siting rule are left out of this summary because they may conflict with state law; state rules apply to those items.
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080, accessed 2026-10-25.

Review and timing
Every ADU and junior ADU needs an ADU permit and a building permit, reviewed ministerially without a hearing. The City says within 15 business days whether an application is complete, and acts within 60 days of a complete application (otherwise it is deemed granted).
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(D), accessed 2026-10-25.

State-protected ADUs (Class 1)
Allowed if they meet the general rules: one converted ADU and one junior ADU in a single-family home or accessory structure (up to 150 sq ft added for entry); one new detached ADU up to 800 sq ft with 4 ft side and rear setbacks; converted ADUs in non-livable multifamily space (at least one, up to 25% of units); and up to two detached ADUs with a proposed multifamily building or eight with an existing one (not more than the existing units).
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(E)(1), accessed 2026-10-25.

Where ADUs are allowed
Class 1 ADUs: lots in residential or mixed-use zones. Other ADUs: lots zoned for single-family or multifamily homes. Junior ADUs: lots zoned for single-family homes.
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(F)(1), accessed 2026-10-25.

Height
Detached ADU: 16 ft; 18 ft within a half mile of major transit (up to 20 ft to match the main roof pitch) or with a multistory multifamily building. Attached ADU: 25 ft or the zone limit, whichever is lower, and no more than two stories.
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(F)(2), accessed 2026-10-25.

Sprinklers, rentals and sale
Fire sprinklers only if the main home needs them. No rentals shorter than 30 days. No separate sale except as Gov. Code 66341 allows. Septic users need a recent percolation test.
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(F)(3)-(6), accessed 2026-10-25.

Owner occupancy
ADUs have no owner-occupancy rule. A junior ADU needs the owner to live on the property only if it shares a bathroom with the home (not required for a government agency, land trust or housing organization), and a deed restriction is recorded for every junior ADU.
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(F)(7)-(8), accessed 2026-10-25.

Other ADUs (Class 2): size
Up to 850 sq ft (studio or one bedroom) or 1,000 sq ft (two or more bedrooms); an attached ADU is also limited to 50% of the existing home. No size, floor area, front setback, coverage or open-space limit may reduce a Class 2 ADU below 800 sq ft.
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(G)(1), accessed 2026-10-25.

Other ADUs (Class 2): setbacks and coverage
4 ft side and rear setbacks and a 10 ft front setback (no setback when rebuilt in the same place and size). Zone floor area ratio, lot coverage and impervious surface limits apply (Tables 10.44.80.1-3), subject to the 800 sq ft guarantee.
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(G)(2)-(5), accessed 2026-10-25.

Parking (Class 2)
One space per ADU or per bedroom, whichever is less (may be tandem or in setbacks), with no parking needed within a half mile of public transit, in a historic district, for an ADU inside the home or an accessory structure, where on-street permits are not offered, near car share, or with a new home that meets one of these. No replacement parking for a converted or removed garage.
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(G)(7), accessed 2026-10-25.

Fees
No impact fees for junior ADUs or ADUs under 750 sq ft; larger ADUs pay in proportion to the main home. Converted ADUs and junior ADUs on single-family lots usually need no new utility connection.
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(H), accessed 2026-10-25.

Existing conditions
The City will not deny an ADU because of nonconforming conditions or unpermitted structures that are not a safety threat and are not affected by the ADU. For an unpermitted ADU or junior ADU built before 2020, the City may not deny a permit to legalize it because it breaks building standards or the ADU rules, unless a correction is needed for health and safety (Health and Safety Code 17920.3).
Source: Sausalito Municipal Code Sec. 10.44.080 Accessory dwelling units (eCode360; as amended by Ord. 12-2025, Dec. 2, 2025), Sec. 10.44.080(I), accessed 2026-10-25.

Where to ask
Sausalito Community Development Department. The City's ADU page has its ADU information.
Source: City of Sausalito, Accessory Dwelling Units page, accessed 2026-10-25.

California state rules on file

The statewide baseline recorded from state law and the HCD ADU Handbook.

Detached size cap described in state law
1,200 sq ft. Recorded in this rules file from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Side and rear setback cap for a new ADU
4 ft. Recorded in this rules file from Government Code section 66314, which describes a cap on side and rear setbacks for a new ADU.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Setback for a conversion of an existing structure
No additional setback, as recorded in this rules file from Government Code section 66314 for a conversion of an existing structure.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Minimum lot size
A city may not impose a minimum lot size for an ADU, as recorded in this rules file from Government Code section 66314.
Source: California Government Code section 66314, 66314, accessed 2026-10-16.

Minimum unit the handbook says cities must allow
At least an 800 sq ft ADU with 4 ft side and rear setbacks. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(3).
Source: HCD ADU Handbook, 66321(b)(3); handbook updated March 2026, accessed 2026-10-16.

Detached height described in the handbook
16 ft, or 18 ft or 20 ft in some cases. The HCD ADU Handbook (updated March 2026) describes this under section 66321(b)(4).
Source: HCD ADU Handbook, 66321(b)(4); handbook updated March 2026, accessed 2026-10-16.

Permit decision deadline
60 days. Recorded in this rules file from Government Code section 66317(a)(3): the permitting agency must decide on (approve or deny) a completed ADU application within 60 days when an existing single-family or multifamily dwelling is on the lot. Section 66317(a)(1) says the application is considered ministerially, without discretionary review or a hearing.
Source: California Government Code section 66317, 66317(a)(1), (a)(3), accessed 2026-10-17.

Owner-occupancy requirement
None. Recorded in this rules file from Government Code section 66315: a local agency may not impose an owner-occupancy requirement on an ADU. It may require that the property be used for rentals of terms 30 days or longer. The HCD ADU Handbook (updated March 2026) describes the same rule.
Source: California Government Code section 66315, 66315; HCD ADU Handbook updated March 2026, accessed 2026-10-17.

Parking near public transit
No parking standards within one-half mile walking distance of public transit. Recorded in this rules file from Government Code section 66322(a)(1). Section 66322(a) lists several other cases where parking standards may not be imposed.
Source: California Government Code section 66322, 66322(a), accessed 2026-10-17.

Ministerial categories
The HCD ADU Handbook (updated March 2026) states that Government Code section 66323 sets four ministerial categories. This rules file does not restate those four categories.
Source: HCD ADU Handbook, 66323; handbook updated March 2026, accessed 2026-10-16.

Fire Hazard Severity Zones
If your lot is in a Fire Hazard Severity Zone, the CAL FIRE Office of the State Fire Marshal says in Information Bulletin 25-004 (issued March 3, 2025): “Fire Hazard Severity Zones (FHSZs) should not restrict the development of Accessory Dwelling Units (ADUs). However, additional building standards may be necessary, including but not limited to California Fire Code Chapter 49 and California Building Code Chapter 7A.” State ADU law does not itself bar an ADU there. A city or county may still apply its building code, including wildfire-resistant construction (Gov. Code 66314(d)(8)); require side and rear setbacks “sufficient for fire and safety” for a unit converted under 66323(a)(1); and decline parking in setbacks on specific fire and life safety findings (66314(d)(10)(B)). It may also consider public safety when it designates where ADUs may be permitted (66314(a)). Sprinklers can't be required in an ADU or JADU if the primary residence doesn't need them (66314(d)(12), 66323(d)). Some cities and counties still apply their own fire-zone limits. Where this summary has one, it is listed with the local rules. This summary does not look up your lot. Check the CAL FIRE Fire Hazard Severity Zone map viewer linked from the State Fire Marshal's Fire Hazard Severity Zones page: https://experience.arcgis.com/experience/5065c998b4b0462f9ec3c6c226c610a9
Source: CAL FIRE Office of the State Fire Marshal Information Bulletin 25-004, page 4, issued March 3, 2025; Gov. Code 66314, 66323, accessed 2026-10-20.

State baseline on the directory → · State ADU rules on the homepage →

Can I build an ADU in Sausalito?

State law sets a baseline for ADUs in Sausalito, and the local standards on file are listed on this page. Whether a specific lot can add an ADU depends on zoning, utilities, and other site facts this page does not measure. Confirm with the City of Sausalito Community Development Department, or run a free address summary.

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