Accessory Dwelling Units

Accessory Dwelling Units contribute needed housing to the City of Gilroy’s housing stock and enhance housing opportunities. ADUs and junior ADUs are allowed on single-family, duplex and multifamily dwelling zoned properties that include a proposed or existing primary residential dwelling.  

The Helpful Links, list of Required Documents, and Frequently Asked Questions is intended to help you through the process of applying for and building an Accessory Dwelling Unit on your property. 

Please feel free to contact the Planning Department if you need further assistance. Please email the Planning Division for fastest service. Alternatively, you can call 408-846-0440 and leave a message.


CalHFA's ADU Grant Program – The CalHFA ADU Grant Program can provide up to $40,000 in assistance to reimburse homeowners for predevelopment costs necessary to build and occupy an Accessory Dwelling Unit (ADU). The ADU Grant provides up to $40,000 to reimburse pre-development and non-reoccurring closing costs associated with the construction of the ADU. Predevelopment costs include site prep, architectural designs, permits, soil tests, impact fees, property survey, and energy reports. The objective of the ADU Grant Program is to create more housing units in California.

Accessory Dwelling Unit Handbook (HCD)

ADU Resource Center (AIA) 

The ABCs of ADUs (AARP)

Other External Websites (via HCD)


 How do I apply for a permit?

Start with the Building Department's Accessory Dwelling Units & Jr. ADU Plan Submittal Guidelines

Once you have your plans ready to go, you will Submit all forms and plans, including a Building Permit Application to

For general building permit questions, please call (408) 846-0451.

What else do I need?

You will need to complete and record a Deed Restriction that acknowledges the following:

(a)  Short-term rentals are prohibited. An accessory dwelling unit shall not be rented for periods less than thirty (30) days.

(b) An accessory dwelling unit shall not be sold separately from the primary residential structure.

(c) Junior ADUs require owner occupancy on the property where the JADU is located.

ADU Deed Restriction Template

Junior ADU Deed Restriction Template

Recording Instructions


Where can I find the City's ADU regulations?


What is my zoning district?

Please email the Planning Division with your address and we can look up your zoning for you.

What is an ADU?

“Accessory dwelling unit” means an attached or a detached residential dwelling unit that provides complete independent living facilities for one (1) or more persons and is located on a lot with a proposed or existing primary residence. It shall include permanent provisions for living, sleeping, eating, cooking and a food preparation area (which may include countertop appliances), and sanitation on the same parcel as the single-family or multifamily dwelling is or will be situated.

“Attached accessory dwelling unit” means a residential dwelling unit that is created as a result of internal conversion, addition, or combination thereof made to the primary residential dwelling unit.

“Junior accessory dwelling unit” means a unit that is no more than five hundred (500) square feet in size and contained entirely within a single-family residence. A junior accessory dwelling unit may include separate sanitation facilities, or may share sanitation facilities with the existing structure.

How many ADUs can I have on a Single-family zoned property?

One (1) ADU is allowed when the property contains an existing or proposed primary single-family home. The ADU may be within, attached to, or detached from the proposed or existing primary dwelling.

How many ADUs can I have on a Multi-family zoned property?

Portions of the existing duplex or multifamily dwelling structure(s) that are not used as livable space (including, but not limited to, storage rooms, boiler rooms, passageways, attics, basements, or garages) may be converted for use as an ADU; provided, that the total number of units must not exceed twenty-five percent (25%) of the existing multifamily dwelling units or one (1) unit, whichever is greater.

An owner may also construct up to a maximum of two (2) detached ADUs on a lot that has an existing permitted duplex or multifamily dwelling, subject to a height limit of sixteen (16) feet and four (4) foot rear yard and side setbacks.  The height allowance will increase on January 1, 2023. 

What is the maximum square footage allowed? 

A detached accessory dwelling unit shall not exceed a maximum size of one thousand (1,000) square feet in floor area.

An attached accessory dwelling unit, including internal conversions of existing primary living space, shall be permitted but shall not exceed fifty percent (50%) of the existing primary dwelling gross floor area, garage area excluded. Notwithstanding this requirement, an 850 square-foot one-bedroom or 1,000 square-foot two-or-more-bedroom accessory dwelling unit shall be allowed.

NOTE: The square footage noted above is consistent with current state law, as of 2022. The City's code will be updated in mid-2023 accordingly.

What is the height limit?

Currently, the maximum height for an accessory dwelling unit shall be one (1) story and sixteen (16) feet. The height allowance will increase on January 1, 2023.

The maximum height for a structure composed of a detached garage and an accessory dwelling unit that is proposed to be constructed above a detached garage shall be twenty-four (24) feet.

What are the setbacks for an ADU?

An accessory dwelling unit must not encroach upon the required front yard area, unless necessary to allow a dwelling unit to be built pursuant to State Law.

A setback of four (4) feet from the side and rear lot lines shall be required for a newly constructed accessory dwelling unit that is not constructed in the same location and to the same dimensions as an existing structure.

No additional zoning setback is required for conversion of an existing permitted accessory structure, living area, or garage space, or conversion of a structure that is constructed in the same location and to the same dimensions as the existing structure

What are the parking requirements?

One (1) additional parking space shall be required for a newly constructed accessory dwelling unit, which may be located within the front setback, in tandem and in an existing driveway that provides at least eighteen (18) feet of clearance from the back of sidewalk. Parking in setback areas or tandem parking may be denied if found to be infeasible due to specific site or life safety conditions.

Notwithstanding the above, a parking stall will not be required for an accessory dwelling unit that meets any of the following criteria:

  1. The accessory dwelling unit is created as a result of the conversion of existing area of the single-family residence or existing permitted single-family residential accessory structure.
  2. An existing single-family residential garage, carport or parking structure is converted or demolished to accommodate an accessory dwelling unit in the same location.
  3. The accessory dwelling unit is within one-half (1/2) mile walking distance of a public transit station, such as a bus stop or train station.
  4. The property is within an architecturally and historically significant historic district.
  5. On-street parking permits are required in the area but not offered to the occupant of the residential accessory dwelling unit.
  6. A car share vehicle is located within one (1) block of the accessory dwelling unit.

What are the Junior accessory dwelling unit standards?

Owner occupancy of the property shall be required. The owner must reside in the primary single-family residence, junior accessory dwelling unit or separate residential accessory dwelling unit constructed on the property in compliance with this article.

One (1) junior accessory dwelling unit may be permitted per residential lot zoned for a single-family residential use; provided, that the lot has not more than one (1) existing or proposed single-family residence, and not more than one (1) attached or detached residential accessory dwelling unit if constructed in compliance with all applicable limitations of section 30.54.30.

The unit must be constructed within the existing walls of an existing or proposed single-family dwelling.

The square footage of the unit shall be at least the minimum size required for an efficiency unit, up to a maximum size of five hundred (500) square feet in floor area.

An efficiency kitchen must be provided in the unit which shall include all of the following:

  1. A cooking facility with appliances, which may be countertop appliances.
  2. A food preparation counter and storage cabinets that are of reasonable size in relation to the size of the junior accessory dwelling unit.

The unit may include separate bathroom facilities or may share bathroom facilities contained within the primary residence.

No separate utility connection, connection fee or capacity charge, or parking space shall be required for a junior accessory dwelling unit. 

Are fire sprinklers required?

The installation of fire sprinklers shall not be required for an accessory dwelling unit if sprinklers are not otherwise required for the primary residence.
 Are we able to use water & power from the existing residence?

Subject to Government Code Section 65852.2(f)(4), an accessory dwelling unit must have an independent electrical subpanel, water heating and space heating equipment within the unit or be readily accessible to the occupant on the exterior of the unit. The accessory dwelling unit must contain water, sewer and gas and/or electric utility connections that are in working condition upon its occupancy. The accessory dwelling unit may be serviced by the primary residence or may have separate utility meters.