The California ADU Law Guide: Changes, Building, and Requirements

Posted on: December 5th, 2024

What are ADUs and what are the ADU laws in California? Who qualifies for an ADU grant? What are the benefits of ADUs? How big can your ADU be? How much does an ADU cost? In this article, we intend to answer all of your questions about ADUs and the ADU laws in California. We serve the entire Sacramento area including Roseville with everything from general contracting to home painting.

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What are ADUs?

ADUs, or Accessory Dwelling Units, are small, secondary housing units that are located on the same property as a primary residence. Sometimes they are referred to as “In-law suites”, “granny flats”, or backyard cottages. ADUs can be attached to the main house, such as a basement or garage conversion, or detached as a standalone structure.

Typically, they are self-contained, meaning they have their own kitchen, bathroom, and living space separate from the primary residence. ADUs are becoming more and more popular in urban areas as a way to address housing shortages and provide affordable housing options. Local regulations relating to ADUs can vary, so their design and use may be subject to zoning laws and permit requirements. 

California ADU Laws

California has become a leader in promoting ADUs as a solution to the state’s housing crisis. In recent years, the state has passed several laws to make it easier for homeowners to build ADUs on their properties (California Government Code 65852.2). Key aspects of California ADU laws are:

1. Zoning and Location Flexibility 

  • No Single-Family Zoning Restrictions:  In California, cities and counties are generally prohibited from restricting ADUs in single-family residential zones. This allows homeowners to build an ADU on their property regardless of whether the area is zoned for single-family use.
  •  Setbacks: ADUs can often be built with reduced setbacks (distance from property lines). For example, the law allows ADUs to be located as close as 4 feet from the side and rear property lines, depending on local ordinances. 

2. Size Limits

  • Detached ADUs: The maximum size for a detached ADU is typically 1,200 square feet, but this can vary depending on the local jurisdiction.
  • Attached ADUs: ADUs that are attached to the primary residence (such as converting a garage or basement) can be up to50% of the existing home’s living area or 1,200 square feet (whichever is smaller). 
  • Junior ADUs (JADUs): These are smaller ADUs (usually up to 500 square feet) that are created within the existing footprint of a single-family home, such as converting a bedroom or part of a garage. They must have a separate entrance.

3. Parking Requirements

  • For single-family homes, no additional parking is required for ADUs if the ADU is within half a mile of public transportation, or if the ADU is part of an existing building (like a garage conversion). There is also no additional parking requirement if the property is within a designated historic district.
  • For multifamily properties, one parking space per ADU may be required unless certain conditions (like proximity to transit) apply.

4. Owner-Occupancy Requirement

  • California used to have an owner-occupancy requirement for either the primary residence of the ADU,but that requirement was eliminated in 2020. Now, homeowners can rent out both the primary residence and the ADU without the owner needing to live in either one.

5. Streamlined Approval Process

  • Local governments are prohibited from denying ADU applications that meet state standards, and approval must occur within 60 days of submission for compliant applicant applications. In some cases, cities can issue an ADU building permit without public hearings, provided the ADU meets zoning, design and building code standards.

6. Design and Aesthetic Requirements

  • Local cities can have specific design standards for ADUs (for example, architectural consistency with the primary home), but these must not be overly restrictive. ADUs should be allowed in residential zones, regardless of local zoning classifications.

7. Impact Fees

  • Impact fees for things like water, sewage, and traffic infrastructure are limited for ADUs that are smaller than 750 square feet. For ADUs over 750 square feet, impact fees may apply but must be proportional to the size of the primary home. 

Changes in California ADU Laws in Recent Years

AB 68(2019) and AB 881 (2019) are both bills that significantly reduced local barriers to ADU construction by limiting local jurisdictions’ ability to impose restrictions on ADU development including size, parking requirements, and owner-occupancy requirements.

SB 13 (2019) further reduced impact fees for smaller ADUs.

SB 9 (2021) allows some single-family residential properties to build multiple ADUs on the same lot, (lot splitting), potentially increasing density. 

AB 2221 (2022) expanded provisions that would allow ADUs to be built on multifamily lots addressing housing shortages in areas with higher population density. 

Local Jurisdictions

California state law provides a general framework, but cities and counties can still impose specific rules around ADUs, such as height limits, green building standards, fencing/landscaping standards, and design review requirements. It is a good rule of thumb to always check with your local planning or building department to ensure that you are in compliance with local ordinances, as cities may have additional allowances or restrictions.

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Benefits of ADUs in California

ADU’s can provide several benefits for both property owners and communities. Some of the key advantages are:

  • Affordable Housing: ADUs can provide an affordable housing option for renters, which can be especially valuable in high-demand urban areas where housing costs are on the rise.
  • Additional Income For Homeowners: As a homeowner, you can rent out your ADU which will provide you with a source of passive income. This can help with your mortgage payments or other expenses.
  • Multigenerational Living: ADU’s offer a flexible space for multigenerational families by providing a separate living area for adult children, elderly parents, or other family members while maintaining privacy.
  • Efficient Use of Land: ADUs make good use of available space on residential properties,which can help increase housing density without requiring additional land development.
  • Reduced Environmental Impact: Since ADUs are typically smaller and more energy-efficient than typical single-family homes, they can have a lower environmental footprint. They often use fewer resources, and if built sustainably, ADUs can support environmentally friendly living. 
  • Flexibility and Adaptability: Your ADU can be designed for a variety of uses including a guest house, home office, or studio which makes them adaptable if/when your needs change over time.
  • Support for Aging in Place: For homeowners, especially seniors, ADUs provide a way to stay close to family white maintaining independence in a separate living space.
  • Community and Economic Growth: Increased housing options, like ADUs, can help alleviate housing shortages and support local economies by creating new rental opportunities without needing large-scale developments.
  • Improved Property Value: In many cases, adding an ADU can increase the value of your property, especially in areas where housing demand is high.

Who Qualifies For ADU Grants in Sacramento?

In cities such as Sacramento, ADU grants are typically designed to encourage the construction of affordable housing and also to encourage homeowners to add ADUs to their properties. The specific qualifications for ADU grants may vary depending on the program, but in general, they tend to be available to the following groups:

  • Low-to-Moderate-Income Homeowners: Many of the ADU grant programs in California prioritize homeowners with low to moderate incomes because they are more likely to benefit from financial assistance to build an ADU. Income qualifications can vary based on the program and are often tied to the area median income (AMI) for the city you live in (Sacramento, Los Angeles, San Diego, etc). 
  • First-Time Homeowners: Some programs are available to first-time homeowners who wish to add an ADU to their property as a way of increasing affordable housing options.
  • Homeowners with a Primary Residence in Sacramento: Most ADU incentives or grants require that the homeowner’s primary residence be located within the city or county where they plan to build the ADU.
  • Homeowners Complying with Local Zoning and Building Regulations: To qualify for certain grants or subsidies,homeowners must ensure their AdU project complies with local zoning codes, permits,and building regulations. This typically involves submitting plans for approval.
  • Non-Profit Organizations or Developers:  In some cases, grants may be available to non-profit organizations or developers building ADUs for affordable purposes. 

Examples of ADU Incentive Programs

  • Sacramento’s ADU Incentive Program: This program, offered by the City of Sacramento, provides financial incentives for the construction of ADUs, particularly for affordable housing development. The exact eligibility criteria and grant amounts may vary based on the program’s current funding and goals.
  • State Programs: State-level programs have been rolled out in California in order to promote  ADU development, which may provide financial incentives or low-interest loans for qualifying homeowners. To get the most up-to-date information on ADU grants in Sacramento, it’s a good idea to contact the CIty of Sacramento’s Housing and Development Department or consult with a local housing organization that specializes in ADU programs.

How Much Does an ADU Cost in California?

The cost of an ADU in California can vary widely depending on factors such as size, design, location, materials, and whether you’re building a detached or attached unit. Here are a few rough estimates:

  • Small ADUs (up to 500 square feet) cost around $100,000-$150,000:  One-bedroom units or studios are usually less expensive but still involve costs for permits, site preparation, and construction.
  • Medium-sized ADUs (500-800 square feet) cost around $150,000-$200,000. This size is often suitable for a one- or two-bedroom unit. Costs rise with the complexity of the design and quality of the finishes.
  • Larger ADUs (800-1,200 square feet) cost around $250,000-$400,000. Larger units, higher-end finishes, or extensive landscaping tend to be on the higher end of the cost spectrum.

The California ADU Law Guide Conclusion

California’s AdU laws have been designed to encourage the creation of additional housing units to combat the state’s housing crisis. If you have any further questions about ADU laws in California, or are considering adding an ADU to your existing property,  give us at LNL Construction a call. Our years of experience, expertise, and attention to detail guarantee a finished product you will be thrilled with. We service the Sacramento area and Placer County. 

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