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Santa Cruz, California: ADU Regulations

Date Updated:



RS-1A, RS-2A, RS-5A, RS-10A
R-1-5, R-1-7, R-1-10
R-L, R-M, R-H
R-T(A), R-T(B), AND R-T(D)

Number of ADUs allowed:

Single-family: 1 ADU and 1 Junior ADU
Multi-family: 2 new construction and up to 25% the number of existing units for Conversion

Types of ADUs allowed:

Attached, Conversion, Single Story Detached, Two Story Detached, Junior


Not required until 2025 for ADUs. Required for JADUs.

Lot size:


Maximum ADU size:

Attached: Largest of 50% of primary residence or 800 sq.ft.
Conversion: 1,200 sq.ft.
Detached: 10% of net lot area up to 1,200 sq.ft.

Note: Accessory units that utilize alternative green construction methods that cause the exterior wall thickness to be greater than normal shall have the unit square footage size measured similar to the interior square footage of a traditional frame house.


Two bedroom max




ADU must provide separate provisions for cooking and eating.
Junior must provided efficiency kitchen


ADU must provide separate provisions for sanitation.

Junior may share with primary residence.


None required. However, 1 minimum space for ADUs in the Coastal Zone, and one additional parking per bedroom after the first


Attached: Zone district standards apply to primary residence.
Conversion: Maintain existing.
Detached - Single Story: 3’ side, 3’ Rear
Detached - Two Story: For first story 3’ side. For portions above 16’, 5’ side, 5’ rear. When ADU faces an alley, 4’ side, 4’ rear.
Note: Fire Department regulations should be assessed on a project by project basis.


Attached: Apply zoning standards

Conversion: Maintain existing plus 2’

Detached - One Story: 16’ at roof peak

Detached - Two Story: 22' at roof peak. If built within 4’ of rear and side property line, then 16’.


Attached ADUs may occupy any level of the primary dwelling if it is designed as an integral part of the primary dwelling and meets the setbacks required for said dwelling.
When an ADU is adjacent to an alley or the Monterey Bay Sanctuary Scenic Trail, the ADU is encouraged to be oriented toward the alley or trail with the front access door and windows facing the alley.

Fire Safety:

Fire Sprinklers in ADUs are only mandatory if also present in or required for the primary structure.

Note: Fire Department regulations should be assessed on a project by project basis.


The ADU should share architectural compatible with the primary residence. Additionally, ADU doors, windows, and balconies should be situated to preserve privacy.

The two-story detached ADU shall limit the major access stairs, decks, entry doors, and windows to the interior of the lot, an alley, or the Monterey Bay Sanctuary Scenic Trail if applicable. Windows that impact the privacy of the neighboring side or rear yards shall be minimized.

If the design of the principal single-family dwelling has special roof features that should be matched on the detached ADU to enhance design compatibility, the maximum allowed building height of the accessory dwelling unit may be exceeded in order to include such similar special roof features subject to review and approval of the zoning administrator.

Rear Yard Coverage:



The entrance to the ADU shall face the interior of the lot unless the ADU is directly accessible from an alley, a public street, or the Monterey Bay Sanctuary Scenic Trail.

Substandard Lots:

A Substandard Lot, as defined in Section 24.22.520, is any parcel that is smaller than the required square footage for the zone district or less than 50’ wide. When a new ADU is built, the following standards apply to all ADUs 

The maximum allowable lot coverage for all structures shall be forty-five percent. Lot coverage shall include the footprints of the first floor, garage (attached and detached), decks and porches (greater than thirty (30) inches in height and not cantilevered), and any second-story cantilevered projection (enclosed or open) beyond two and one-half feet.

Decks under thirty (30) inches in height or fully cantilevered with no vertical support posts do not count toward lot coverage for this purpose. Second-story enclosed cantilevered areas that project less than thirty (30) inches from the building wall do not count toward lot coverage. For such areas that project more than thirty (30) inches from the building wall, only the floor area that projects more than thirty (30) inches shall be counted as lot coverage.

The floor area for all second stories shall not exceed fifty percent of the first floor area for all structures, except in cases where the first floor area of the structure to which a second story is being added constitutes thirty (30) percent or less of the net lot area.

Continuous long walls parallel to the side property line with narrow side yards shall be minimized.

Landscaping shall be required at least for front yard areas
Structures, landscaping or other features shall incorporate methods to lessen the visibility of garages on a street facade.

Source Code:

Important Note: Rules and regulations are updated and changed frequently. It’s one of our jobs to be up to speed and navigate those regulations. Let us know if our website isn’t up to date or if you have any information that could help. Cheers!