Accessory Dwelling Units

About the Dwellings

An accessory dwelling (ADU), also commonly referred to as a granny flat, may be added residential properties that are developed with a single-family home. Properties with multi-family units, including duplexes, may not add an ADU to the property.


The exterior of the ADU should be compatible in appearance with the primary home and utilize quality exterior materials such as high-quality wood, stucco, stone, or masonry.

Window Placement

An A that is 15 feet or less from a residential unit on an adjacent parcel shall not have windows that directly face windows on the other unit. A detached ADU located closer than 10 feet to a side lot line or 20 feet from a rear lot line shall have no 2nd floor windows facing the side or rear except for obscure glass.


The placement of the ADU must comply with the same setbacks that apply to the primary home. The setbacks are determined by the zoning district for the parcel. Refer to the Development Standards page for setbacks by zoning district. If you do not know the zoning designation for your property, you may complete an online Zoning Information Request Form.

Height Limit

ADUs that are detached from the primary home may not exceed 20 feet in height. If the ADU is above a detached garage, the maximum height is 25 feet. If the ADU is attached to the primary home, the maximum allowable height is 30 feet.

Size Limitations & Requirements

An ADU attached to the primary home may be up to 60% of the size of the primary home. If the ADU is detached, the maximum allowance is 1,200 square feet, regardless of the size of the primary home. For example, if a primary home is 1,800 square feet, including attached garage space, an attached ADU may be no more than 1,080 square feet (60% of 1,800 square feet).

Secondary Units With Attached Garage

If the secondary unit has its own attached garage, you may exempt no more than 400 square feet of the garage space in the calculation. There may be no internal doorways from the living unit to the attached garage.

Maximum Lot Coverage

The maximum lot coverage of all structures on a parcel must comply with the zoning requirements. Please contact the Planning Division to find out the maximum allowable lot coverage for your property.

Conversion of Existing Building

In some cases, an existing building (garage, barn, etc.) may be converted to living space but it should also be noted that commonly when a garage or barn is constructed, they are built for storage not for living space so significant structural and energy will probably be required.


Although, parking should be considered when planning an ADU, the demonstration that the site can accommodate additional parking is not required.

Other Requirements

  • Secondary units may not be offered for sale apart from the principal unit.
  • Secondary units may have no more than 2 bedrooms.
  • Secondary units can be rented to anyone. The occupants do not have to be related to the owners of the property and do not have to be over a certain age. Also, it is not required that the owners of the primary home live on the property.
  • Your project will be reviewed to make sure that the design and placement of the secondary unit works well with the primary home and fits well into the surrounding neighborhood.
  • Secondary units may be attached to the primary home providing the secondary unit has a separate entrance.
  • All secondary dwelling units require a Building Permit and must comply with applicable building, fire, health and safety codes, as well with zoning requirements.

How to Apply

Plans will need to be submitted in order to obtain a Building Permit. Pick up an application package from the Building and Safety Division for a list of plans and information that is required for your project.

Additional Information

This information is provided as a courtesy and identifies requirements for residential secondary dwellings. Additional information may be found within the Zoning Code Section 106.42.210 (PDF). Any discrepancy between this information and the Zoning Code shall control. For additional information, contact the Planning Division at 916-727-4740.