Accessory Dwelling Units

ADU, Accessory Dwelling Unit or JADU, Junior Accessory Dwelling Unit is a way to provide additional housing on the same lot. Its intention is to provide affordable housing options for renters, family members, the elderly, or caregivers. It can also help 1st time buyers to increase income to afford a new home. The following are some key points on ADU regulations:

Review period – An application for ADU or JADU for lots with a single-family dwelling shall be deemed approved, or denied, within 60 days from a completed application. The prior regulation was 120 days.
In San Francisco, if the ADU requires an expansion, neighbors within 150 feet radius and neighborhood groups will be notified for a 30-day public review period. During the 30-day period, a discretionary review process will apply.

Number of ADU allow – Under state law, you can provide (1) ADU and (1) JADU per lot, within the proposed or existing single-family dwelling, if certain conditions are met. For multi-family buildings, state law allows up to 25% of the unit count;

In San Francisco, if (4) or less legal dwelling units are on a lot, only (1) ADU is allowed. If (5) or more legal dwelling units are on a lot, then an unlimited number of ADUs are permitted under S.F. Planning Code. Then, the determination on the number of ADUs will depend on the S.F. Building Code for the abilities to provide natural light, ventilation, and two exits.

Size of the ADU – Under state law, the maximum size of a detached ADU is 1200 sq.ft. for more than one bedroom; local city requirements may vary. For example, the City of Millbrae is 1000 sq.ft. maximum for a detached ADU of more than one bedroom;

Size of the JADU – Under state law, the maximum size of a JADU within the primary dwelling is 500 sq.ft.; local city requirements may vary.

Density Limit – Adding an ADU does not change the allowable density limit of the lot.

Short-term Rentals – ADU cannot be used as short-term rentals.

Owner occupancy requirement – Owner occupancy is not required on ADUs until 2025, which means both the primary dwelling and the ADU can be rented.

For JADUs, owner occupancy is required at the primary dwelling or the JADU.

Rent Controlled – ADUs need to provide affordable rent to very low, low, or moderate-income households.

The information provided is for general reference; Every site has unique challenges, we have the training and experience to help you decide if an ADU makes sense for you from a cost, benefit & lifestyle point-of-view. If you think an ADU makes sense, we can help you to explore design options.