Category: ADU

Accessory Dwelling Units

08.29.2024,

ADU, Accessory Dwelling Unit or JADU, Junior Accessory Dwelling Unit is a way to provide additional housing on single or multi-family lots. 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:

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 within the existing building. 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.

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

JADU owner occupancy requirement – Owner occupancy is required at the primary dwelling or the JADU.

Height Limits – State law height limit is 16 feet for a detached ADU; In San Francisco, if the lot has an existing or proposed single or multi-family dwelling that is within ½ mile walking distance of a major transit stop, then, the height limit can be 18 feet. In San Francisco, an attached ADU height limit is 25 feet.

Other items to consider for Statewide ADU – The rear & side setback are 4’ from the property line; Lot size, lot coverage, floor area ratio, & open space requirements are exempt for ADU up to 800 s.f. and 16 feet high.

Unit Legalization – In San Francisco, there is also a unit legalization program to help you legalize an in-law unit without the ADU process. In that process, the unit needs to be existed prior to January 1, 2013.

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.

1,000 s.f. ADU in Alameda.
1,000 s.f. ADU in Millbrae

Senate Bill 9, SB 9

12.06.2023,

California State Senate Bill 9 (SB 9) would allow a 2 residential units development in a single-family residential zone to be considered ministerially, without discretionary review, public hearing & CEQA, if the development meets certain requirements by the local agency. SB 9 said this development approach does not require owner occupancy.  Neither unit would be subject to rent control & the units could be sold as condominiums. 

If your property is located within an urban area & your property was not established through a lot split prior to Senate Bill 9; Then you can subdivide your lot into 2 parcels and build 2 homes on each of the 2 new lots allowing for a total of 4 units. SB 9 said the lot split approach requires the applicant to occupy one of the units as their principal residence for a minimum of 3 years. SB 9 allows the local agency to ministerially approve a parcel map for an Urban Lot Split that meets certain requirements by the local agency.

The review & approval process under SB 9 will be “objective” in terms of zoning standards, subdivision standards, and design standards.

Key points to consider:

  1. Qualify Projects must be zoned in a single-family lot; Not a historic site or district; Cannot alter or demolish rent-controlled housing, housing that was Ellis Act in the last 15 years, or housing occupied by a tenant in the last 3 years.
  2. Minimum unit area 800 square feet.
  3. Minimum 4 feet setback at rear & side. (5 feet would be better in some situation)
  4. San Francisco requires minimum 25 feet separation between existing & new buildings.
  5. One parking per unit; Some local agency may consider no parking if parcel located ½ mile walking distance of transit.
  6. Cannot be use as short-term rentals.
  7. If units are attached, it must be design as condominium to allow for separate sale.
  8. Urban Lot Split should result in 2 approximately equal-sized lots (60-40 split). Each new lot is at least 1,200 square feet. Urbanized area is an area with 50,000 or more people. See US Census Bureau for urban area reference maps.