Frequent Ask Questions
What are ADUs?
Accessory Dwelling Units (ADUs) have been known by many names: granny flats, in-law units, backyard cottages, secondary units and more. No matter what you call them, ADUs are an innovative, affordable, effective option for adding much-needed housing in California. HCD is the state’s leader on local ADU ordinances, which — while optional — have grown exponentially in number as more cities, counties, and homeowners become interested in ADUs as one solution to increasing the supply of affordable housing.
What are the benefits of ADUs?
- ADUs are an affordable type of home to construct in California because they do not require paying for land, major new infrastructure, structured parking, or elevators.
- ADUs can provide a source of income for homeowners.
- ADUs are built with cost-effective wood frame construction, which is significantly less costly than homes in new multifamily infill buildings.
- ADUs allow extended families to be near one another while maintaining privacy.
- ADUs can provide as much living space as many newly-built apartments and condominiums, and they’re suited well for couples, small families, friends, young people, and seniors.
- ADUs give homeowners the flexibility to share independent living areas with family members and others, allowing seniors to age in place as they require more care.
Can I create an ADU if I have multiple detached dwellings on a lot?
Yes. A lot where there are currently multiple detached single-family dwellings is eligible for creation of one ADU per lot by converting space within the proposed or existing space of a single-family dwelling or existing structure or a new construction detached ADU subject to certain development standards.
Can I build an ADU in a historic district, or if the primary residence is subject to historic preservation?
Yes. ADUs are allowed within a historic district, and on lots where the primary residence is subject to historic preservation.
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.
Can parking requirements exceed one space per unit or bedroom?
No. Parking requirements for ADUs shall not exceed one parking space per unit or bedroom, whichever is less. These spaces may be provided as tandem parking on a driveway. Guest parking spaces shall not be required for ADUs under any circumstances.
Can impact fees be charged for an ADU less than 750 square feet?
No. An ADU is exempt from incurring impact fees from local agencies, special districts, and water corporations if less than 750 square feet. Should an ADU be 750 square feet or larger, impact fees shall be charged proportionately in relation to the square footage of the ADU to the square footage of the primary dwelling unit.
Are solar panels required for new construction ADUs?
Yes, newly constructed ADUs are subject to the Energy Code requirement to provide solar panels if the unit(s) is a newly constructed, non-manufactured, detached ADU. Per the California Energy Commission (CEC), the panels can be installed on the ADU or on the primary dwelling unit. ADUs that are constructed within existing space, or as an addition to existing homes, including detached additions where an existing detached building is converted from non-residential to residential space, are not subject to the Energy Code requirement to provide solar panels.
Can my local Homeowners Association (HOA) prohibit the construction of an ADU or JADU?
No. Assembly Bill 670 (2019) and AB 3182 (2020) amended Section 4751, 4740, and 4741 of the Civil Code to preclude common interest developments from prohibiting or unreasonably restricting the construction or use, including the renting or leasing of, an ADU on a lot zoned for single-family residential use. Covenants, conditions and restrictions (CC&Rs) that either effectively prohibit or unreasonably restrict the construction or use of an ADU or JADU on such lots are void and unenforceable or may be liable for actual damages and payment of a civil penalty. Applicants who encounter issues with creating ADUs or JADUs within CC&Rs are encouraged to reach out to HCD for additional guidance.