ADUs in California

  • A statewide exemption ADU is an ADU of up to 800 square feet, 16 feet in height, as potentially limited by a local agency, and with 4 feet side and rear yard setbacks. ADU law requires that no lot coverage, floor area ratio, open space, or minimum lot size will preclude the construction of a statewide exemption ADU.
  • Over the past few years it’s become much easier for single-family property owners in California to build accessory dwelling units (ADUs, also known as in-law apartments, granny flats or backyard cottages) and junior accessory dwelling units (JADUs). JADUs are essentially units built within existing structures, e.g., bedrooms with attached bathrooms converted into separate rental units. Prior to 2017, local jurisdictions often used confusing and burdensome permitting requirements to impede ADU/JADU construction. Many towns banned garage conversions, or forced owners to continue residing on converted properties. But statewide ADU/JADU standards enacted over the last five years, coupled with restraints on local control, have fostered a backyard building boom.

Size Requirements

Is there a minimum lot size requirement?

  • No, while local governments may impose standards on ADUs, these standards shall not include minimum lot size requirements. Further, lot coverage requirements cannot preclude the creation of a statewide exemption ADU (800 square feet ADU with a height limitation of 16 feet and 4 feet side and rear yard setbacks). If lot coverage requirements do not allow such an ADU, an automatic exception or waiver should be given to appropriate development standards such as lot coverage, floor area or open space requirements. Local governments may continue to enforce building and health and safety standards and may consider design, landscape, and other standards to facilitate compatibility.

Call us today for a free estimate to learn more about this. Tel. (310)-984-9398 or Contact us: and you’ll learn everything you need to know about the ADU process – from planning & permitting to designing & construction.

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