Accessory Dwelling Ordinance

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ADU Image(Cursive).001


What is an ADU? | Benefits of an ADUContact

Public Hearing 

On Monday, July 13, 2020, the City Council reviewed a proposed urgency ordinance to amend the zoning ordinance to amend regulations related to Accessory Dwelling Units (ADU). The urgency ordinance was not adopted at the hearing and the City Council directed staff to present the ordinance to the Planning Commission. The Planning Commission is tentatively scheduled to consider the ADU Ordinance on August 18, 2020.

 City Council discussed the following regulations:

  • Maximum height for detached ADUs
  • ADU floor area ratio and lot coverage requirements
  • Square footage bonus for Americans with Disabilities Act (ADA) compliant ADUs and ADUs on lots larger than 10,000 sq. ft.
  • Short-term rental regulations for ADUs

(Staff Report / Draft ADU Ordinance / Video


How to Apply for an ADU 

To apply for a permit to construct an ADU, fill out the ADU Completeness Checklist and a Building Permit application. During the Shelter-In-Place order, the City will accept online permit submittals via email with credit card payment over the phone. Submit completed construction plans, building permit application, and ADU checklist to

For new detached ADUs, please note that a fire flow test is required as part of the permit submittal process to determine water availability to the site and to assist fire sprinkler system design, if necessary. Visit the City's Fire Flow webpage to schedule a test with Engineering Department. Typical lead time is three weeks. 

Having trouble getting started? Visit: for a step-by-step guide to start the design process, apply for permits, guidance through the construction process, and tips for moving-in. The Second Unit Center is a County of San Mateo Home for All program that provides information and tools to make it easier for homeowners to build second units, helping increase the housing supply in the County. The Second Unit Center developed a workbook and website to help residents with the process of constructing an ADU, see below.

Second Unit Workbook (English / Spanish)

For more information, go here.   


New ADU  Fees
     0 to 400 sq. ft. or converting existing garage to new ADU  $2,656
 401 to 600 sq. ft.  $3,247 
 601 to 800 sq. ft.  $3,543


2020 Amendments

New State housing laws that went into effect on January 1, 2020, grant more flexibility to construct Accessory Dwelling Units (ADU) across California. Redwood City is in the process of updating its local ADU ordinance to be compliant with State regulations. The Planning Commission and City Council held a Joint Study Session on February 10, 2020 to discuss the new State ADU regulations and the required considerations for adopting a local ordinance. No formal action took place at the meeting - see video of the meeting here  

In the interim, the City will review ADU projects under the State ADU regulations. Below is a summary of new changes to the State ADU law.

Development Standards

  • Cities are required to allow junior accessory dwelling units (JADUs). These are units of up to 500 square feet of converted space contained entirely within a single-family home. A JADU may share a bathroom with the existing home.
  • ADUs will be allowed in multi-family units. Conversion of uninhabited spaces, including garages, will be allowed for at least one ADU or up to 25% of units in multi-family buildings. Plus, up to two detached ADUs with 4-foot setbacks will also be allowed.
  • Cities must allow a minimum of 850 square feet for a one-bedroom ADU, or 1,000 square feet for an ADU with more than one bedroom.
  • Cities are prohibited from implementing any lot coverage, floor area ratio, and/or open space requirements for detached ADUs.

 Process Updates

  • Cities may not impose impact fees on ADUs less than 750 square feet. 
  • There is a 5-year moratorium on local owner-occupancy restrictions.
  • Mandatory 5-year stay of enforcement on unpermitted ADUs, if they meet health and safety standards.
  • Short-term rentals of ADUs or JADUs are not permitted.
  • California Department of Housing and Community Development (HCD) & the Attorney General can enforce compliance if a new local ordinance is out of compliance, but it provides a 30-day right to sure or state findings to support the local ordinance.

For more information and a full list of new State ADU laws, go here. (Provided by the San Mateo County Department of Housing)


What is an Accessory Dwelling Unit?

An Accessory Dwelling Unit (ADU) is a smaller living unit on a property that has a single-family residence. It is complete with its own kitchen and bathroom facilities.  Common names for an ADU include in-law unit, secondary unit, and backyard cottage. ADUs are not allowed to be used exclusively as a short-term rental unit.

Benefits of an ADU

  • Extra living space for family or guests
  • Housing for aging parents, caregivers or adult children
  • Efficient use of existing infrastructure
  • Rental income



Apollo Rojas
Senior Planner
(650) 780-7365