Basic Requirements for Accessory Dwelling Units

  • The parcel must be owner-occupied as evidenced by the filing of a home owner's property tax exemption, or other appropriate documentation.*
  • The parcel must be zoned to allow residential uses, or have a General Plan designation of either Residential or Agriculture.
  • The parcel may have no more than one existing dwelling unit. An ADU can also be constructed concurrently with a new single family dwelling.
  • Only structures that were constructed legally may be converted to a Conversion ADU (See SCCC 13.10.681(E)). Other structures may be used for ADUs, but will be permitted as New Construction.
  • ADUs are allowed on any residential lot with an existing single family home, regardless of parcel size or if parcel size is smaller than the district minimum. Parcels on septic must ensure their sanitation systems are appropriately sized for the additional loads.
  • New Vacation Rentals will not allowed on parcels with ADUs, any existing Vacation Rental permit must be forfeited before applying for a permit to build an ADU.
  • Most projects will require only a building permit, which must be approved or denied within 120 days.
  • Full ADU Ordinance

* For the construction of ADUs within subdivisions or elsewhere where the developer will not be the final occupant, owner-occupancy requirements apply to the purchase of a property w/an ADU, but not to the developer, and occupancy of the ADU will be permitted upon the filing of a Homeowner’s Tax Exemption.

Parking

  • No new parking space is required for:
    • Conversion ADUs,
    • ADUs attached to the primary home or to any garage, or
    • Within ½ mile of transit stops with frequent service (GIS layer available (insert link to County GIS): Land Use and General Plan>ADU Parking not Required).
    • Within 1 block of car share (as shown by applicant)
  • New Construction, detached ADUs require one additional parking space.
  • The primary home on the property must meet the current zoning requirements for parking; OR
    • If the existing home does not meet current parking requirements, and the ADU does not trigger a requirement for a new parking space, the existing number of parking spaces must be maintained. Spaces can be relocated and reconfigured as long as there is no net loss of off-street parking spaces on the property.

Site Standards

  • ADUs built on the second story above a garage are eligible for side and rear setbacks of 5’, and garages are eligible for reduced setbacks with low-level development permit.
  • Height of an ADU above a garage is 24’ maximum with 20’ exterior walls when detached inside the Urban Services Line (USL), or outside the USL with a reduced setback.
  • Height of detached ADUs inside the USL is limited to 17’ with 15’ exterior walls
  • Height of detached ADUs outside the USL is determined by the standards for the zone district (typically 28’).
  • The minimum distance between an ADU and any other structure is 3’.
  • Maximum size of ADU is based on parcel size, and location inside or outside the Urban Services Line (USL)
  • Find out the maximum allowable ADU size for your parcel
Example building envelope: New Construction ADU above detached garage.
  New Construction ADUs: Parcel Size
< 5,000 sq. ft. 5,000-10,000 sq. ft. 10,000 sq. ft to 1 acre >1 acre
INSIDE USL 10% of Parcel Size 640 sq. ft 800 sq. ft. 800 sq. ft.
OUTSIDE USL 800 sq. ft 800 sq. ft 1,000 sq. ft. 1,200 sq. ft.
  Conversion ADUs: Parcel Size
< 5,000 sq. ft. 5,000-10,000 sq. ft. 10,000 sq. ft to 1 acre >1 acre
INSIDE USL 50% of primary dwelling or 640 sq. ft., whichever is less 640 sq. ft 800 sq. ft. 800 sq. ft.
OUTSIDE USL 50% of primary dwelling or 640 sq. ft., whichever is less 800 sq. ft 1,000 sq. ft. 1,200 sq. ft.
  MINIMUM SETBACKS MAXIMUM HEIGHT MAXIMUM NUMBER OF STORIES
FRONT SIDE REAR
INSIDE USL
DETACHED NEW CONSTRUCTION Same as zone district standards 17 ft. overall, 15 ft. exterior side wall 1
NEW CONSTRUCTION ABOVE DETACHED GARAGE Same as zone district standards 5 ft. 5 ft. 24 ft. overall, 20 ft. exterior wall 2
ATTACHED TO PRIMARY DWELLING Same as zone district standards
OUTSIDE USL
DETACHED NEW CONSTRUCTION Same as zone district standards
NEW CONSTRUCTION ABOVE DETACHED GARAGE Same as zone district standards 5 ft. 5 ft. 24 ft. overall, 20 ft. exterior wall 2
ATTACHED TO PRIMARY DWELLING Same as zone district standards

Fees

The amount of the permitting, planning, and other fees varies with the characteristics of the project and with the location of the property. To the extent fees are based on size of the unit, number of bedrooms, or project valuation, your ADU design can influence the fee cost. See the Financing Guide for more information. Certain fees are waived for ADUs as follows:

  • Waiver of the sewer and water connection fees for Conversion ADUs
  • Reduced building permit fees for Conversion ADUs.
  • Waiver of TIA/Roadway/Roadside fees when no parking is required for ADU.
  • Waiver of Affordable Housing Impact fee for Conversion ADUs and first 500sf of New Construction ADUs. Area above 500 square feet charged at the lowest rate of $2 per square foot.

Alternatives to ADUs

  • A "limited food prep area" is allowed, in addition to a kitchen, in a single-family home (allows for sink, prep space, and 110V electrical appliances)
  • Adding a food prep area to an existing bedroom, den, or family room could create a separate living space for a family member or a renter.

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