An Accessory Dwelling Unit (ADU) is an accessory unit to the primary dwelling with complete independent living facilities for one or more persons (sleeping, eating, cooking, and sanitation).
The Town of Corte Madera encourages the construction of accessory dwelling units. ADUs are an important strategy to increase the diversity of housing options available in Corte Madera. ADUs are generally smaller than primary residences and offer studio, one- and two-bedroom housing options. These small units can function as rental housing or accommodate multi-generational families on one property.
ADUs are subject to different zoning regulations compared to other types of buildings. These ADU regulations are provided in Corte Madera Municipal Code Chapter 18.31 as well as California Government Code sections 65852.2 and 65852.22.
An ADU can be attached to, converted from part of, or detached from the primary residence. An ADU must include a kitchen, bathroom, and sleeping area, and must have its own exterior entrance.
There are three types of ADUs (not including JADUs):
- Detached: A new construction ADU that is separated from the primary dwelling by at least 3 feet. Detached ADU height is limited to 16 feet unless it is above a garage, in which case the maximum height is 25 feet. There is a minimum 4-foot setback from the side and rear property lines. The front yard setback requirement is the same as the primary structure.
- Attached: A new construction ADU that shares walls and is attached to the primary dwelling. Attached ADUs can be 25 feet tall. Setback distances are the same as for detached ADUs.
- Converted Existing Space: Existing space, such as all or portions of a master bedroom, attached garage, storage area, or similar, on the lot of the primary residence that is converted into an independent living unit.
Maximum ADU size is dependent on the type of ADU, number of bedrooms proposed, and the maximum allowed building area on the property. However, regardless of existing site conditions, an 800 square foot ADU is allowed.
A Junior Accessory Dwelling Unit (JADU) is a specific type of conversion of existing space that is contained entirely within an existing or proposed single-family residence. A JADU is 500 square feet or less, contains an efficiency kitchen, and sanitation facilities may be provided in the unit or shared with the residence. A JADU requires the property owner to reside in either the primary residence or the JADU.
Corte Madera allows one ADU or JADU per single-family property, with one ADU plus one JADU allowed under certain conditions. On properties with multifamily housing types such as apartment buildings, multiple ADUs are allowed subject to California Government Code section 65852.2.
The Town of Corte Madera has adopted Accessory Dwelling Unit (ADU) and Junior Accessory Dwelling Unit (JADU) standards (Chapter 18.31). As new State ADU/JADU regulations are adopted, the Ordinance will be updated to be consistent with State Law. Below are helpful tools and information regarding the Town’s regulations and the design, building, and planning process for ADUs.
- ADU/JADU Standards - all about development standards and permit requirements for ADUs/JADUs. Development standards are objective regulations related to size, height, setbacks, parking, etc.
- 2023 What's New Handout - key takeaways from two new ADU bills effective January 1, 2023.
- Adumarin.org - a website about building ADUs, created in partnership with 10 local cities and towns in Marin. The site contains budget calculators, sample floor plans, and other resources for property owners who want to build an ADU.
- ADU project webpage - archived information about the Town's past ADU ordinance updates.
- Housing and Community Development (HCD) Technical Advisory on ADUs - a summary of ADU State Laws, frequently asked questions, and resources from State of California Housing and Community Development.
ADU Approval Process:
All ADU construction projects require a building permit. Some ADU projects also require approval from the Planning Division as a first step before the building permit application. These types of ADUs include:
- New construction detached ADUs larger than 800 square feet.
- New construction attached ADUs.
- ADUs that are proposed as part of a larger project that requires Planning approval.
- New attached/detached >800sf - use this form if the ADU is larger than 800sf.
- In an existing structure or a new detached ≤ 800sf - use this form is the ADU is within an existing structure or is detached and less than or equal to 800sf
- Junior ADU - use this form for a Junior ADU
Please contact Planning Staff by email, phone, or in person to discuss any questions you have about building an ADU or JADU in the Town of Corte Madera.