2024 Guide to the California ADU Law: Everything You Need to Know

Last Updated: April 18th, 2024

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Welcome to your essential guide on California’s Accessory Dwelling Units (ADUs) Law.

Amidst a 45% surge in ADU applications since 2020, these units are transforming California’s housing landscape.

Known as granny flats, in-law units, or backyard cottages, ADUs are a blend of practicality and innovation, addressing the state’s housing crisis while providing homeowners with additional income.

This guide delves into the ADU law’s complexities and opportunities, covering zoning, design, permits, and community impact.

We’ll explore the benefits, navigate requirements, and showcase successful ADU examples, all to equip you with everything you need to know about integrating ADUs into California’s residential areas.

As we dive into the details, remember that ADUs symbolize California’s commitment to innovative and sustainable housing solutions.

Let’s explore how ADUs are shaping a more inclusive future in California housing.

Benefits of the California ADU Law

The California ADU Law stands as a pivotal response to the state’s housing challenges, offering a suite of benefits that cater to homeowners, tenants, and the community at large.

  • Increased Housing Options: Addressing the state’s critical housing shortage, ADUs provide a practical solution by adding affordable living spaces to existing residential properties. These units, ranging from converted garages to bespoke backyard dwellings, not only diversify housing options but also integrate seamlessly into established neighborhoods, offering affordable alternatives in areas where traditional housing might be out of reach.
  • Additional Rental Income: Homeowners gain a significant financial advantage with ADUs. In California’s high-cost rental markets, these units can be a steady source of income, helping homeowners offset mortgages or bolster retirement savings. This economic benefit extends beyond individual gains, contributing to broader financial stability within the community.
  • Multigenerational Living: ADUs uniquely support multigenerational living arrangements. They offer the perfect balance between proximity for familial support and independence for privacy. This setup is particularly valuable for families looking to care for aging relatives or provide space for young adults, blending convenience with the comfort of having loved ones nearby.
  • Sustainable Development: Aligning with California’s environmental goals, ADUs contribute to sustainable housing development. Their smaller size and the reuse of existing space minimize land use and environmental impact. Additionally, many ADUs incorporate eco-friendly design elements, such as energy-efficient appliances and sustainable materials, further reducing their ecological footprint.

In essence, the California ADU Law isn’t just a regulatory framework; it’s a strategic approach to enriching the state’s housing landscape.

Transforming underutilized spaces into functional living areas, addresses affordability, fosters family cohesion, and champions sustainable living practices.

Requirements and Restrictions under the California ADU Law

Understanding the requirements and restrictions of the California ADU Law is crucial for any homeowner or developer considering an ADU project.

Here’s what you need to know about the key aspects:

  • Size Requirements and Lot Coverage: The law is clear – there are no minimum lot size requirements for ADUs. This means more properties can potentially host an ADU, broadening the scope of where these units can be built. When it comes to lot coverage, floor area ratio, or open space requirements, they cannot impede the creation of a statewide exemption ADU. This type of ADU, defined under Government Code section 65852, subdivision (e), can be up to 800 square feet, with a height of 16 feet and four-foot side and rear yard setbacks. Importantly, these criteria apply regardless of the zoning and development standards of the local ordinance.
  • Minimum and Maximum Unit Sizes: Local governments have the authority to set minimum and maximum unit sizes for both attached and detached ADUs. However, these sizes must accommodate at least an 850 square-foot ADU, or 1,000 square feet if the ADU has more than one bedroom. In areas without specific ADU ordinances, the maximum size for a new detached ADU is 1,200 square feet, and for an attached ADU, up to 50% of the existing primary dwelling’s floor area (at a minimum of 800 square feet). It’s also possible for maximum unit sizes to exceed 1,200 square feet if allowed by local ordinances.
  • Conversion of Existing Structures: An existing accessory structure or a part of the primary residence converted to an ADU is exempt from these unit size requirements. For instance, a 3,000-square-foot barn converted into an ADU wouldn’t be subject to local unit size limits. However, any expansion beyond 150 square feet for such conversions must align with the size maximums set by State ADU Law or local regulations.
  • Limiting ADU Size Based on the Primary Dwelling: Local jurisdictions can use a percentage of the primary dwelling’s size to determine the maximum size of an attached ADU. For example, an ADU might be restricted to no more than 50% of the primary dwelling’s size. However, this limitation cannot result in an ADU smaller than the state-mandated minimum sizes.

In summary, while the California ADU Law provides significant flexibility in developing ADUs, it’s essential to be mindful of local ordinances that may introduce additional specifications.

Understanding these nuanced requirements ensures that your ADU project is not only compliant but also maximizes its potential within the legal framework.

The Process of Building an ADU in California: Step-by-Step Guide

Building an Accessory Dwelling Unit (ADU) in California can be a rewarding project, but it requires careful planning and adherence to specific steps. Here’s a step-by-step guide to help navigate the process:

  • Research and Planning: Before anything else, thorough research is key. This involves understanding local zoning laws and the California ADU regulations. Homeowners should assess their property to determine the most feasible type of ADU (attached, detached, or conversion). Consider factors like available space, accessibility, and how the ADU will integrate with the existing structure.
  • Architectural Design & Blueprints: Once you have a clear idea of what’s permissible on your property, the next step is designing your ADU. Hiring a skilled architect or designer who is familiar with ADU projects and local codes is crucial. They can help create a design that not only meets your needs but also adheres to all zoning and building regulations. This stage results in detailed blueprints and plans, which are necessary for obtaining permits.
  • Obtaining Permits and Approvals: With your plans in hand, the next step is to apply for the necessary building permits. This process involves submitting your blueprints to the local building department and possibly other agencies, depending on your location and the specifics of your project. Be prepared for this stage to take some time, as it involves reviews for compliance with building codes and local ordinances. Remember, under California law, local agencies are required to review and act on ADU permit applications within 60 days.
  • Construction Process: Once you have all the necessary permits, construction can begin. Hiring a reputable contractor with ADU experience is advisable. The construction phase includes laying the foundation, framing, roofing, installing utilities, and interior and exterior finishing. Regular inspections by local authorities are typically required to ensure compliance with building codes.
  • Final Inspection and Approval: Upon completion of construction, a final inspection by the local building department is required. This is to ensure that the ADU has been built according to the approved plans and complies with all building and safety standards. Once it passes inspection, you’ll receive a certificate of occupancy, which officially allows the ADU to be inhabited.

Each step in the process is crucial for the successful completion of an ADU. It’s important to stay organized, be patient, and work closely with professionals who can guide you through each stage of this exciting project.

Frequently Asked Questions about the California ADU Law

Below are some of the most commonly asked questions about the California ADU Law, specifically focusing on rent control regulations and financing options for ADU projects.

Q1: Are ADUs subject to rent control regulations in California?

A1: In California, whether an ADU is subject to rent control depends on several factors, including the year it was built and the local jurisdiction’s rent control laws. Generally, ADUs built after February 1, 1995, are not subject to state rent control under the Costa-Hawkins Rental Housing Act.

However, local rent control ordinances may have different criteria, so it’s important to check with your local housing department for specific regulations in your area.

Q2: What financing options are available for building an ADU in California?

A2: Homeowners looking to finance an ADU have several options:

  • Home Equity Loans: Leveraging the equity in your primary residence can be a cost-effective way to finance an ADU.
  • Cash-Out Refinance: This involves refinancing your existing mortgage and borrowing more than what you currently owe to cover the cost of the ADU.
  • Personal Loans or Lines of Credit: These are unsecured loans that can be used for ADU construction but often come with higher interest rates.
  • ADU-specific Loans: Some lenders offer loans specifically designed for ADU construction.
  • Government Loans and Grants: In some cases, state and local governments provide loans or grants for ADU construction, especially if the unit will be used for affordable housing.

Q3: Are there any incentives for building an ADU in California?

A3: Yes, California offers several incentives to encourage ADU construction:

  • Fee Waivers: Some local jurisdictions waive or reduce impact fees for ADU construction.
  • Pre-Approved Plans: Certain cities offer pre-approved ADU plans to streamline the process and reduce design costs.
  • Property Tax Incentives: Under certain conditions, building an ADU may not trigger a reassessment of your property value, thus not increasing your property taxes.
  • Affordable Housing Incentives: If you rent your ADU at an affordable rate to low-income tenants, you might qualify for additional grants or loans.

Q4: Can I use my ADU as a short-term rental?

A4: This depends on local city and county ordinances. Some areas may allow ADUs to be used as short-term rentals, while others restrict them to long-term housing to address local housing shortages. It’s essential to check your local regulations before planning to use your ADU as a short-term rental property.