Accessory dwelling units

An accessory dwelling unit (ADU) is a dwelling unit on a residential lot which provides complete independent living facilities for one or more persons, and includes permanent provisions for living, sleeping, eating, cooking, and sanitation independent of the main dwelling(s). ADUs are sometimes called an “in-law unit” or a secondary dwelling unit. ADUs, and junior ADUs, or JADUs, have been the focus of recent State legislation, as they can provide needed housing without materially changing the visual character of a neighborhood. The Planning and Building Divisions are committed to making the ADU review process as predictable and streamlined as possible for our customers. Please review the information below for details regarding the ADU requirements by building type, the process for new proposals and links to the related handouts and State legislation. Links are also available through the related documents section to the right of your screen if viewing through a web browser.

Requirements and guidelines

The table below contains general requirements related to ADUs. For specifics regarding setbacks, allowable heights, sizes and other development regulations for an ADU on a lot with a single-family residence or existing multi-family building please review the appropriate webpage to the left and the materials in table 2, below. Please click the zoning layer through the city’s GIS map to look up the zoning for a particular parcel. The map layer for zoning may not be activated by default, but can be applied after following the preceding link. Specific requirements for development vary between single-family or multi-family residential zoning districts according to the zoning of the parcel of interest.

 General ADU requirements
Minimum lot size
Minimum unit size
150 sf
Individual sale/subdivision
Not permitted, unless associated with an affordable housing nonprofit per AB587
Aesthetic similarity to primary dwelling
Not required
Exterior access
Must provide exterior access separate from the primary dwelling for all ADU/JADUs. 
Sanitation facilities (restroom)
Must be independent for ADU, JADU can be shared with primary dwelling 
Cooking facilities (kitchen)
Must be independent and must include the following:
  1. Permanent range
  2. Counters
  3. Refrigerator
  4. Sink
Owner-occupancy requirement None for ADUs permitted between 1/1/2020 and 1/1/2025, for a JADU the owner is required to reside in either the primary dwelling unit or the JADU.
Rental term 30 days, minimum, for ADUs permitted after 1/1/2020
Impact fees No impact fees for ADU < 750 sf

 Requirements and resources by building type
SF ADU webpage and section 16.79.050
 Multifamily and mixed use
MF ADU webpage and section 16.79.090

Review process

ADU applications that meet all Zoning Ordinance requirements may be reviewed and approved by staff. Prior to starting such an application, staff recommends coming in to the counter (see hours at top right of this page) to discuss the ADU regulations. Project plans (including a site plan, floor plans, floor area and building coverage diagrams, and elevations) are required with ADU applications.

Following the Planning Division's recommended preliminary review, applicants who are proposing fully-compliant ADUs will coordinate with the Building Division to confirm the items required for submittal of a building permit application. In general, the following guidelines are applicable to ADU building permits, depending on the specific proposal:
Please note that new ADUs require a number of standard fees, including (for ADUs 750 square feet and greater) proportional impact fees. One such impact fee are the school fees charged by the local school district. As a hypothetical example, if the primary dwelling unit is 2,000 square feet and the ADU is 1,000 square feet, and the school fee was $3.79/square foot the ADU would be responsible for $3,790 in school fees. Please consult the Building Division to confirm the school district for your property, the fees vary by district. The Building Division can also provide detailed fee quotes prior to an application.

ADU applications that do not meet all Zoning Ordinance requirements may be reviewed and acted on with a Use Permit by the Planning Commission (with the exception of the density and subdivision requirements, which may not be modified). Please contact the Planning Division if you are considering any such application for discretionary review. 

Background and additional resources

A number of State bills regarding Accessory Dwelling Units (ADUs) became effective January 1, 2020. The following State Government Code sections may be referenced, however please defer to the information above for Menlo Park specific regulations: