Cotati City Council
Agenda Staff Report
Item type: REGULAR AGENDA (ACTION)
To: City Council
Subject: Presentation on designs for Accessory Dwelling Units (ADUs) Date: May 23, 2023
Written by: Autumn Buss, Associate Planner
Recommendation
It is recommended by the Community Development Department that the City Council receive a presentation on the pre-reviewed designs for Accessory Dwelling Units (ADUs) available through the Napa Sonoma ADU Center, and provide feedback to staff on the designs to receive promotion through the City’s ADU outreach program.
I. Background
An Accessory Dwelling Unit (ADU) is a residential dwelling unit, typically of a modest size, that is secondary, or “accessory,” to an existing primary dwelling unit on a property.
Also known as “granny units,” ADUs are an increasingly popular way to add residential units in a community due to their relatively low cost to build and the opportunity they present to leverage existing backyard space in otherwise built-out neighborhoods. ADUs can create space for extended family living, as well as a revenue opportunity for homeowners, and can also be an important tool for creating affordable housing.
In 2017, the California legislature passed a law allowing ADUs in all residentially-zoned areas in all jurisdictions across the state and relaxing certain development requirements in order to make ADUs easier to build. Many cities and counties, including Cotati, adopted their own ADU ordinances to mirror the State law.
Interest in ADUs in Cotati has been strong over the past few years. In fact, in 2022, the only building permits issued for new residential construction were for ADUs (8 permits).
Furthermore, Cotati’s recently adopted Housing Element, a component of the City’s General Plan, includes promotion of ADU development as a key strategy to meet Regional Housing Needs Allocation (RHNA) goals. The Housing Element targets construction of 40 ADUs over the next 8 years to help address Cotati’s housing needs, and also includes several strategies to promote ADU development. See Attachment 1:
Housing Element Program 2-3 for more information.
The City has expressed its support for ADU construction in Cotati not only through its Housing Element goals, but also through its partnership with the Napa Sonoma ADU Center (www.napasonomaadu.org). The Napa Sonoma ADU Center is a not-for-profit project to support ADU development in both Sonoma and Napa Counties, including homeowner consultation, on-line tools and resources, and promotion.
The Center also offers a library of designs for detached, or freestanding, ADUs, including site-built designs that have been pre-reviewed in collaboration with local jurisdictions for compliance with their building codes, and pre-fabricated (modular) designs that have been pre-reviewed by the State of California Housing and Community Development Department for compliance with the California Building Code. Pre-reviewed designs can reduce the cost of developing an ADU by streamlining the local Building Permit review process and using less staff time and resources. All ADU development requires a Building Permit, regardless of pre-reviewed status.
Cotati has supported the Napa Sonoma ADU Center by providing staff time to assist in the pre-review process for 10 site-built ADU designs, which appear in the Center’s design library which is available on their website. In addition, the design library features 11 prefabricated ADU designs that have been pre-reviewed for State Building Code compliance.
II. Analysis/Discussion
In furtherance of Housing Element goals to promote ADU development, City staff plans to develop an outreach program including a webpage promoting ADUs and featuring a selection of the pre-reviewed designs, both site-built and pre-fabricated, that are available through the Napa Sonoma ADU Center’s design library. The ADU designs promoted by the City may be the same as those offered by the Center, or they may be a subset that the City selects as particularly suited to Cotati’s architectural character.
It is important to note that State law, and Cotati’s ADU ordinance, allow ADUs to be constructed without design review. Planning approval of ADUs is ministerial, and consists of review for non-design standards including setbacks, square footage, and height. A Building Permit is required.
A key aspect of ADU design is that a detached ADU’s visibility from the street and neighboring properties may be somewhat reduced due several applicable development standards. For instance, the maximum height of a detached ADU is as follows: 1) 16 feet with minimum setbacks of 4 feet from rear and side property lines (18 feet within ½ mile of the SMART station or where a multifamily, multistory structure is present as the primary structure); or 2) Up to the maximum height limit for the primary residence (varies, typically 28 feet in residential zones), if the ADU meets the side and rear setback requirements for the primary residence, which vary by zoning district but are a minimum of 10 feet from the rear and side property lines. ADUs were previously prohibited in front setbacks, although new State law that went into effect January 1, 2023, requires that ADUs of up to 800 square feet in size be allowed in the front setback if they cannot feasibly be accommodated elsewhere on the property.
Attachment 2: ADU Design Library for Cotati includes an image of each pre-reviewed site-built and pre-fabricated ADU design that is listed as suitable for Cotati in the Napa Sonoma ADU Center’s design library. This includes 21 total designs.
III. Summary and Staff Recommendation
Staff recommends that the City Council receive the presentation on the pre-reviewed designs for Accessory Dwelling Units (ADUs) available through the Napa Sonoma ADU Center, and provide feedback to staff on the designs to receive promotion through the City’s ADU outreach program.
Attachments:
Attachment 1 Housing Element Program 2-3 (PDF)
Attachment 2 ADU Design Library for Cotati (PDF)