An accessory dwelling unit (ADU) is a secondary housing unit, with a full kitchen (sink, refrigerator, cooking appliance, counters and cabinet storage) and bath, typically found on a single-family residential lot.
The term “accessory dwelling unit” is the most commonly used term across the country to describe this type of housing. While their structural forms vary, ADUs share some common traits and face common design and development challenges.
In particular, the fact that they can be secondary housing units on single-family zoned lots places ADUs into a unique category of housing. ADUs also have some other distinguishing characteristics that help further define, differentiate, and distinguish them from other housing types.
State law allows a special type of ADU called a Junior ADU (JADU). A JADU can be created from an existing bedroom, attached garage, or other portions of a single-family residence, and be located entirely within the existing walls of that single-family home. The JADU may have a separate entrance from the main dwelling and its own kitchen, but the JADU must be no more than 500 square feet in size. A private bathroom is not required as long as the JADU has full access to a bathroom in the primary dwelling. No off-street parking is required.
Accessory Dwelling Units (ADUs) are commonly called: granny flats, in-law units, backyard cottages, secondary units and guest quarters. Recently the State of California legislature has passed several bills in 2017, 2018 and 2019 to ease the creation of ADUs in areas zoned to allow single-family or multifamily use. ADUs can come in many shapes and sizes, but are always a self-contained home that is smaller than the main house, and legally part of the same property. ADUs always contain a kitchen, bathroom, and a place to sleep. An ADU may be detached, attached, converted from existing interior space, converted from a garage, or built above a garage.
The Assessor’s appraisal staff will use standardized appraisal methods to determine the value to assess to the newly constructed ADU or JADU. On completion, the appraiser may look at the cost, income, and sales comparison methods to determine the market value added for the newly constructed improvement.
New construction to the existing home, including ADU, JADU and patios, pools etc. is assessed at market value upon completion. However, the existing land and structures not involved in new construction will not be included in the reassessment. The increment of value determined for the newly constructed property (ADU or JADU), will be added to the existing assessed improvement value.
|Existing Assessed Value:||$220,000||$300,000||$520,000|
|Market value of ADU upon completion:||$100,000||$100,000|
|New Assessed value:||$220,000||$400,000||$620,000|
The decision about how the square footage of an ADU or JADU shows on Assessor records depends on the following:
Junior Accessory Dwelling Units (JADUs) can be constructed from an existing legally permitted bedroom, attached garage, or other portions of a single-family residence. They may be up to 500 square feet in size, and must include an efficiency kitchen (sink, stove, refrigerator and counter). Some JADUs have their own bathroom, while others share with the main house. JADUs are a lower cost way to add a second unit, because the construction costs are much lower than a traditional second unit.