Secondary units, also known as accessory dwelling units, ADUs, or granny flats, are small dwelling units that can efficiently leverage the land and existing infrastructure of single-family neighborhoods without significant change to the character of a neighborhood. ADUs may provide an income opportunity for homeowners; may help people provide housing to their extended family members or disabled persons; and may create more affordable housing opportunities for our community.
On June 19, 2018, the City Council will consider significant changes to the zoning rules and development standards for ADUs in San Jose. Current development standards for ADUs in San Jose are found in Section 20.30.150 of the Zoning Ordinance.
Properties that Qualify for an ADU
At our May 17, 2018 Building Permits & Home Safety Open House, attendees saw a special presentation on requirements for Accessory Dwelling Units (ADUs, also called granny units). View the presentation here.
Property owners can use the Secondary Unit Review Worksheet, which applies current zoning rules, to help determine eligibility for an ADU. Again, please note that these rules may change pending the outcome of the City Council's June 19, 2018 decision.
A Building Permit is required to build an ADU. Your project will be reviewed for conformance with the Zoning Ordinance and California Building Code. Applicants should also review these fire-related directives:
Building Review Requirements for Fire Separation for Secondary Units
Fire Department Review Requirements for Secondary Units
Permit fees for an ADU vary based on the project scope; see the Building Division Fee page for more information.
2018 Secondary Unit Ordinance Update
Based on public input, planning staff proposed updates to Section 20.30 of the Zoning Code to modify the lot size, setbacks, height, parking exemptions, and other provisions for ADUs. On May 9, 2018 meeting, the Planning Commission held a public hearing and reviewed the proposed changes for ADUs; view the memorandum. The commission voted unanimously to recommend that the Council consider and adopt the proposed changes; the item will be heard by the Council on June 19, 2018.
Considerations and Proposed Updates
Zoning District Designation
Allowed in R-1, R-2, and PD (subject to R-1 standards) zoning districts, comprising of single-family residences.
Allow in R-M zoning district, (and on PD lots subject to R-1 standards and lot size), where single-family residences exist.
Minimum Lot Size
(in sq. ft.)
5,445 sq.ft. – for both attached and detached units
Allow on lots with areas between 3,000 sq.ft. and 5,445 sq.ft. with restrictions on unit size. Not allowed on lots <3,000 sq.ft.
Minimum Setbacks from Property Line
0 (conversion), 5 feet
0 feet for existing structures (in compliance with Building and Fire Code); Allow 5 feet minimum from the side and rear property line for new units and for units constructed above a garage.
Single Story – 18 feet maximum, 14 feet mid- roof
Allow up to 22 feet maximum (measured from grade to top of roof) for a detached unit atop an existing garage/accessory structure.
Rear Yard Coverage
Not to exceed 40% for detached Secondary Unit, Accessory Building and Structures (except for pools)
No change proposed.
Detached Secondary Unit - Location
In rear yard, and at least 6 feet away from primary dwelling. Can be attached only to a detached garage.
Allow ADU to be attached to and converted from other existing accessory buildings in addition to garages.
Maximum unit square footage based on lot size
600 sq.ft. (5,445 - 9,000 sq.ft.); 650 sq,ft, (9,001 - 10,000);
800 sq,ft, (10,001+)
Limit to 600 sq.ft. (3,000 – 5,445 sq.ft,)
700 sq.ft, (5,445 - 9,000 sq.ft,);
800 sq.ft, (9,001 - 10,000 sq.ft,);
900 sq.ft, (10,001+ sq.ft,)
Number of Bedrooms
One bedroom or combined living and sleeping area
One bedroom with common living space or combined living and sleeping area
Attached dwelling unit shall NOT exceed 50% of the existing living area of the primary dwelling
Attached dwelling units shall not exceed 50% of the existing or proposed living area of the primary dwelling.
Parking requirements and driveway width
Parking configurations in conformance with State Law
Allow parking within front and side setbacks for a garage conversions into a secondary unit.
Match appearance, and match roof form and pitch
Require visual compatibility with existing primary dwelling.
Junior accessory dwelling unit
Allow maximum 500 square feet limited to up to 50% of the primary dwelling unit
Front Yard Paving
No more than 50% of the front setback shall be paved with asphalt, cement or any other impervious surface.
Allow no more than 50% of the front setback shall be paved with asphalt, cement or any other impervious or pervious surface.
Reduction in required off-street parking spaces
B(1)(a) No more than one dwelling occupies the lot.
Allow no more than one dwelling, in conjunction with an ADU, to occupy the lot.
Secondary unit addition to a single-family lot located on the Historic Resources Inventory
Requires Single-Family House Permit
Waive requirements for a Single-Family House Permit for new detached Secondary Unit or for conversion of existing accessory structure with no exterior alterations.
Add definitions for conversion, Single-Family dwelling unit.