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.
What are JADUs?
Junior Accessory Dwelling Units (JADUs) are allowed to be created within the walls of a proposed or existing single-family residence and shall contain no more than 500 square feet. JADUs offer additional housing options. They may share central systems, contain a basic kitchen utilizing small plug-in appliances, may share a bathroom with the primary dwelling, all to reduce development costs. JADUs present no additional stress on utility services or infrastructure because they simply repurpose existing space within the residence and do not expand the dwellings planned occupancy.
New! New laws effective January 1, 2020
The Legislature further updated ADU and JADU law effective January 1, 2020 to clarify and improve various provisions in order to promote the development of ADUs and junior accessory dwelling units (JADUs). These include allowing ADUs and JADUs to be built concurrently with a single-family dwelling, opening areas where ADUs can be created to include all zoning districts that allow single-family and multifamily uses, modifying fees from utilities such as special districts and water corporations, limited exemptions or reductions in impact fees, and reduced parking requirements. Please see the Accessory Dwelling Unit Technical Assistance memo (PDF) for more information.
Master plan submittal package
An accurate, complete submittal package is required and must include:
- Architectural information, plans, elevations, sections, and details
- Structural information, plans, elevations, sections, and details
- Structural calculations
- Title 24 energy documents, as applicable
- Truss plans and calculations, as applicable
- Indication of Fire sprinklers: Provide a statement as to whether the standard construction plan layout proposes to be equipped with an automatic fire sprinkler system.
- Geotechnical investigation report, as applicable
- For ADUs, you may use code minimum soil valuation for foundation design, or pre-scripted footing sizes if conventional construction is used, or match existing foundation.
- A standard site plan as reference is optional.
- ADUs are a secondary dwelling unit with complete independent living facilities for one or more person. They are an innovative, affordable, effective option to increase the value and space of your home. Today ADUs are known by different names: granny unit, granny flat, in-law unit, in-law cottage, mother-in-law apartment, sidekick home, laneway home, backyard guesthouse, backyard cottage or secondary dwelling unit. ADUs are affordable in California as they do not require paying for land, major new infrastructure, structured parking, or elevators. Further can provide an additional source of income for homeowners.
- What is JADU?
- A Junior ADU (or JADU) is a new category of dwelling units created by the State of California. The main difference is that a JADU is not required to have a dedicated bathroom.
- Architectural Plans for ADUs
- The first step of creating an ADU is to have an architectural plan. If you do not have a plan handy, we are happy to connect you with one of our trusted Architect partners in your area. Our partner architects specialize in various architectural styles and can create an Architectural Permit set for any design styles you have in mind.
- Engineering Services for ADUs
- We have you completely covered when it comes to the engineering required for the ADU. Our engineers can take your ADU vision and iron out the details to ultimately create the ADU plans for construction. We then work with you across the ADU construction and oversee every step of the project.
- What’s are the steps to building an ADU?