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San Jose, California: ADU Regulations

City or County:

San Jose, California

Date Updated:




PD districts subject to approved development standards.

Types of ADUs:

Attached, detached and garage conversions

Tiny Home on Wheels (THOW) on a lot with single family home. Link to THOW checklist here

THOW an only be added to single family homes that does NOT have a detached ADU. Must have a vehicle license.


Single-story and two-story ADUs permitted

Lot Size:


Maximum ADU Floor Area:

Single family up to 9,000 sq.ft.: Detached 1,000 sq.ft., Attached either 800 sq.ft. or 50% of primary residence

Single family > 9,000 sq.ft.: Detached 1,200 sq.ft., Attached either 800 sq.ft. or 50% of primary residence with 1,200 max

Lot with JADU: JADU 500 sf, Detached 800 sq.ft., Attached not allowed

Multifamily: Detached and Attached 800 sq.ft., JADU not allowed

THOW must be at least 150 sq.ft. and maximum 400 sq.ft.

Lot Coverage:



2-bedroom ADU is allowed for units of 800 sq.ft. or greater, otherwise ADU can have only one bedroom or a studio layout. Bedrooms shall not exceed 400 sq.ft.


60 sq.ft. max for entire unit.


Require separate kitchen facilities (permanent range, counters, refrigerator, sink).


Require separate full bathroom. Max 1 bathroom.

Note: Drainage and sewer connections should be assessed on a project by project basis.


1 space required for ADU occupants unless the property qualifies for an exemption under State law. If a garage has been converted, the main dwelling parking space must be replaced, as uncovered or in front or side setback areas. The homeowner may apply for a reduction of one space of required parking. Parking spaces may be configured on-site per state law.


ADUs are subject to the setback requirements for a one-family dwelling in the zoning district in which the one-family dwelling is located, as set forth in this chapter except as follows:

  1. Attached: Same setback requirements as apply to the main house
  2. Detached: 60 feet from front property line, 3 feet rear and side. For second story, 5 feet from both rear and side.
  3. Corner lots: 10 feet on street side.
  4. Lots ½ acre of greater along riparian corridors: 100 feet.
  5. Distance of street curb to all portions of ADU cannot be greater than 200 feet.


If the main house as fire sprinklers, the ADU must have them, as well. If the project is an attached ADU greater than 500 sq. ft. AND the overall gross floor area with the main house exceeds 3,600 sq. ft., then fire sprinklers are required for the entire house and ADU. Sprinklers may be required for a detached ADU that is built with less than a three-foot setback.

All exterior walls of ADU must be within 400 feet of a fire hydrant. Fire hydrants must have a minimum flow of 1,000 gpm at 20 psi.

Note: Fire Department regulations should be assessed on a project by project basis.


Single family: Attached same height as main unit, Detached single-story 18’, Detached two-story 24’, Detached on lot with JADU is 16’ 

Multifamily: Attached maintain same height, Detached 16’
THOW must be no greater than 2 stories and a maximum height of 16ft


Distance from curb to all portions of proposed ADU no more than 200 ft measured along a minimum 3-ft clear path to all sides of the ADU

THOW must be 6 feet from primary home

Rear Yard Coverage:



Detached units do not need to meet any specific design standards, provided there is visual compatibility with existing primary dwelling. Attached ADUs and detached ADUs on properties listed on the Historic Resources Inventory must incorporate architectural style and elements of the primary dwelling. 

Note the THOW requirements below.

Note: Historic Neighborhoods or Districts should be assessed on a project by project basis.


Door cannot be on the same street-facing facade as primary dwelling, unless all other locations for placing front door would require pathway that is unobstructed, clear to the sky and extending from a street to front door.

Tree Removal:

If building an ADU requires removal of an ordinance-size or heritage tree, then must obtain a tree removal permit.

THOW Design Requirements:

Cladding and trim. Materials used on the exterior of THOW shall exclude single piece composite laminates or
interlocked metal sheathing.

Windows and Doors. Windows shall be at least double pane glass and include exterior trim. Windows and
doors shall not have rounded corners.

Roofing. Roofs shall have a minimum of a 12:2 pitch for greater than 50 percent of the roof area and not be
composed of wooden shingles.

No Extensions. All exterior walls and roof shall be fixed with no slide-outs, tip-outs, nor other forms of
mechanically articulating room area extensions.

Mechanical equipment. Must be incorporated into the structure and not located on the roof.

Parked on a paved or alternate pad that includes bumper guards, curbs, or other
installations that adequately prevent movement of the THOW.

The parking area is paved with hard, durable asphaltic paving that is at least 2 inches thick after compaction,
or with cement paving at least 3 inches thick; OR

The parking area is paved with alternative paving materials that may consist of porous asphalt; porous
concrete; permeable interlocking concrete pavers; permeable pavers; decomposed granite, crushed rock or
gravel; plastic or concrete grid system confined on all sides and filled with gravel or grass in the voids; or other
similar materials that meet the following requirements:

a. Permeable interlocking concrete pavers and permeable pavers that have a minimum thickness of 80 mm
(3.14 inches); and
b. Products and underlying drainage material are installed to meet manufacturers’ specifications. Sub-grade
soils shall be compacted as required to meet the product

Source Code:

Important Note: Rules and regulations are updated and changed frequently. It’s one of our jobs to be up to speed and navigate those regulations. Let us know if our website isn’t up to date or if you have any information that could help. Cheers!