ADU California Permitting Requirements: What Should You Know?

Last Updated: January 28th, 2024

Published on


Fill out the form below and one of our team members will contact you to help get started.

Address Form

In the dynamic and often complex world of California real estate, Accessory Dwelling Units (ADUs) have risen as a beacon of innovation and practicality.

Thanks to recent state legislation, the process of adding an ADU to your property has become more streamlined, yet the journey through permitting requirements remains a critical path to navigate.

As of May 2022, the trend toward ADUs in California is not just growing; it’s evolving, reshaping how homeowners and investors view secondary housing solutions.

Consider this: The California Department of Housing and Community Development recently revealed that applications for ADU permits have increased by over 11 times from 2016 to 2020, jumping from approximately 1,300 to over 14,500 applications annually.

This surge reflects not only the increasing demand for ADUs but also the evolving regulatory landscape that governs their creation.

Whether you’re considering a detached ADU in your backyard or transforming your basement into a fully functional living space, understanding the nuances of ADU permits is essential.

This article aims to demystify the ADU permitting process in California, focusing on the key considerations and requirements that homeowners must navigate.

From understanding the specific rooms and amenities required in an ADU to aligning with your city’s unique design and permitting restrictions, we cover it all.

We’ll also delve into how recent legislation has simplified certain aspects of the process, exempting specific ADUs from the planning stage under certain conditions.

Moreover, we’ll guide you through the practical steps of the permit application process.

This includes preparing a list of licensed contractors, presenting a detailed ADU permit plan set, and considering the need for engineering surveys.

With these tools and insights, the path to obtaining the necessary permits, whether they be building, electrical, plumbing, or location-specific permits, becomes clearer and more manageable.

Join us as we explore the essential steps and strategies to successfully navigate the ADU permitting process in California.

From leveraging the CalHFA ADU Grant Program to partnering with turnkey ADU service providers like Spacial, we provide you with the knowledge and resources to make your ADU project a reality.

The Role of Permits in Building an ADU in California

When embarking on the journey of building an Accessory Dwelling Unit (ADU) in California, one of the most critical steps is understanding and obtaining the necessary permits.

These permits are not just bureaucratic formalities; they are essential tools that ensure your ADU is safe, compliant with local regulations, and adds value to your property without legal complications.

Understanding ADU Permits

ADU permits are multifaceted, encompassing various aspects of construction, safety, and design. At their core, these permits serve a dual purpose: they protect the homeowner by ensuring that the ADU meets all safety and zoning requirements, and they preserve community standards and integrity.

  • Building Permits for ADUs: The cornerstone of ADU construction, a building permit, is a must-have. This permit confirms that your ADU design complies with local building codes, including safety, health, and structural standards. Whether you’re converting an existing structure or building a new one, a building permit is non-negotiable.
  • Electrical, Plumbing, and Mechanical Permits: These specialized permits address the specific systems within your ADU. They ensure that the electrical wiring, plumbing, and any mechanical systems like HVAC are up to code, installed correctly, and safe to use.
  • Zoning Permits: Zoning permits focus on the location and external aspects of your ADU. They ensure that your ADU adheres to local land use regulations, including setbacks, height limits, and lot coverage rules. These permits are crucial in maintaining the character and planning integrity of your neighborhood.

Navigating Permit Requirements

Navigating the permit requirements in California can be complex, given the variability in regulations from one jurisdiction to another.

However, some recent legislative changes have streamlined the process for certain types of ADUs.

For instance, under specific criteria set by the 2020 California state law, some ADUs can bypass the planning stage, expediting the permitting process.

Despite these simplifications, the permit process still requires thorough preparation and understanding. Here are some key steps to consider:

  • Research Local Regulations: Start by familiarizing yourself with the specific ADU regulations in your city or county. This research will give you a clear picture of the permits you need and the standards your ADU must meet.
  • Prepare Your Documentation: Gathering the necessary documentation is crucial. This includes detailed architectural plans, a list of licensed contractors, and, in some cases, results from engineering surveys. These documents form the backbone of your permit applications.
  • Consult with Experts: Considering the complexity of ADU regulations, consulting with experts like architects, builders, or specialized ADU service providers can be invaluable. These professionals can help navigate the permitting process, ensuring compliance and efficiency.
  • Understand the Review Process: Be prepared for a review process where local authorities will scrutinize your plans and may request modifications. This process is integral to ensuring that all aspects of your ADU are up to code and fit within community standards.
  • Stay Informed About Changes: ADU regulations and requirements can evolve. Staying informed about any legislative changes or updates in local policies is crucial to avoid any compliance issues down the line.

While obtaining permits for an ADU in California can be a detailed and sometimes challenging process, it’s a fundamental step in ensuring that your ADU project is successful, legal, and beneficial in the long term.

By understanding the role of these permits and preparing adequately, you can navigate this process with greater confidence and clarity.

Understanding Zoning and Land Use Regulations for ADUs

Navigating the zoning and land use regulations for Accessory Dwelling Units (ADUs) in California is a crucial step in the ADU development process.

These regulations, which vary by locality, dictate where and how ADUs can be built, influencing their design, placement, and overall feasibility.

Understanding these rules is key to a smooth ADU project, ensuring that your unit not only meets your needs but also aligns with local planning standards.

Zoning Regulations for ADUs

Zoning regulations are designed to maintain the character and functionality of neighborhoods. When it comes to ADUs, these regulations can include:

  • Size and Height Restrictions: Local zoning laws often specify the maximum size and height of an ADU. These limits are typically based on the size of the primary residence and the overall lot size. For example, some areas may restrict ADUs to a certain percentage of the primary dwelling’s square footage.
  • Placement and Setbacks: Zoning laws also dictate where on your property an ADU can be located. This includes setbacks, which are the minimum distances an ADU must be from property lines, streets, and other structures. Understanding these setback requirements is crucial to determining the viable location for your ADU on your property.
  • Parking Requirements: Depending on your location, there may be specific parking requirements for ADUs. Some jurisdictions require additional parking spaces for the ADU, while others may waive parking requirements, especially if the ADU is located near public transit.
  • Owner-Occupancy Rules: Some areas require the property owner to reside in either the primary dwelling or the ADU. These owner-occupancy rules can affect your plans, especially if you’re considering building an ADU as a rental investment.

Land Use Restrictions for ADUs

In addition to zoning regulations, land use restrictions play a significant role in ADU development. These restrictions can include:

  • Historic Districts and Preservation Areas: If your property is in a historic district or a preservation area, there may be additional restrictions or requirements for building an ADU. These can include limitations on the design, materials, and colors used in construction to ensure consistency with the historical character of the area.
  • Environmental Constraints: Properties located in environmentally sensitive areas, such as coastal zones or hillside areas, may face additional restrictions. These can include limitations on grading, landscaping, and overall footprint to protect the environment.
  • Community Plans and Specific Plans: Some communities have specific plans or area plans that provide detailed land use policies for certain neighborhoods or districts. These plans can include additional guidelines or requirements for ADUs that go beyond the general zoning regulations.

Navigating the Regulations

Successfully navigating zoning and land use regulations requires a combination of research, planning, and sometimes negotiation. Here are some tips to help you through this process:

  • Consult Local Planning Department: Your local planning department is a valuable resource for understanding the specific zoning and land use regulations that apply to your property. They can provide detailed information and guidance on what is and isn’t allowed.
  • Engage with Professionals: Architects, land use attorneys, and ADU specialists can provide expert advice and assistance in navigating the complexities of zoning and land use regulations. They can help you maximize the potential of your property while ensuring compliance.
  • Community Engagement: In some cases, especially in areas with specific plans or community boards, engaging with the community can be beneficial. Understanding and addressing community concerns can smooth the process and help avoid potential objections.
  • Stay Informed and Flexible: Regulations can change, and each project may present unique challenges. Staying informed about current laws and being flexible in your design and planning can help you adapt to any regulatory changes or challenges that arise.

In summary, understanding and complying with zoning and land use regulations is essential for a successful ADU project in California.

By familiarizing yourself with these regulations and seeking the right assistance, you can navigate these requirements effectively, ensuring your ADU is both compliant and functional.

Meeting Building Code Requirements for an ADU Construction

The construction of Accessory Dwelling Units (ADUs) in California, particularly in Los Angeles, is governed by specific building code requirements that ensure safety, functionality, and compliance with local standards. The City of Los Angeles’ Accessory Dwelling Unit Ordinance, adopted on December 11, 2019, and effective from December 19, 2019, has introduced significant updates to these requirements, particularly in the Los Angeles Municipal Code (LAMC) Section 12.22A.33. This section addresses the development standards and requirements for ADUs, Junior Accessory Dwelling Units (JADUs), and Movable Tiny Houses (MTHs).

Updated Building Code Requirements

  • ADU Specifications: An ADU in Los Angeles is defined as an attached or detached residential dwelling unit that provides complete independent living facilities for one or more persons. It must include permanent provisions for living, sleeping, eating, cooking, and sanitation, and be located on the same lot as the primary residence.
  • JADU Characteristics: A JADU is a unit no larger than 500 square feet, contained entirely within a single-family residence. It may have separate sanitation facilities or share them with the existing structure. Importantly, either the JADU or the single-family residence must be owner-occupied.
  • Movable Tiny House (MTH) Guidelines: MTHs are a unique category under the ordinance. They must be licensed and registered with the California Department of Motor Vehicles, meet specific ANSI or NFPA standards, and be certified for compliance. MTHs cannot move under their power and must adhere to size restrictions as per California State Law.

Development Standards and Requirements

The ordinance also outlines specific development standards and requirements:

  • Zoning and Residential Use: ADUs, JADUs, and MTHs are permissible in any zone that allows residential use by right.
  • Parking Regulations: For newly constructed ADUs, parking is not required if the unit is within a half-mile walking distance of public transit. Additionally, when constructing an ADU, replacement parking is not necessary if covered parking is removed.
  • Compliance with Codes: All ADUs must comply with applicable Zoning, Building, and Residential Codes. This includes fire safety regulations, where fire sprinklers are not required for the ADU if they are not required for the primary residence.
  • Solar Panel Requirement: For newly constructed, detached ADUs, solar panels are now a requirement, aligning with California’s push towards sustainable and energy-efficient housing.

Navigating the Updated Requirements

To successfully navigate these updated requirements in Los Angeles, homeowners should:

  • Consult with Local Authorities: Engage with the local planning department to understand the specific implications of the ordinance for your ADU project.
  • Professional Assistance: Given the complexity of these regulations, consulting with architects or builders who specialize in ADUs in Los Angeles can provide invaluable guidance.
  • Stay Informed: Keep abreast of any further updates or changes to local ordinances that might affect your ADU project.
  • Plan Thoroughly: Ensure your ADU plans are comprehensive and align with the latest requirements, including the specifics for JADUs and MTHs, if applicable.

In conclusion, the City of Los Angeles’ ADU Ordinance has introduced specific and detailed requirements for ADU construction.

Understanding and adhering to these updated building code requirements is crucial for a legally compliant, safe, and functional ADU in Los Angeles.

The Permit Application Process: Step-by-Step Guide to Obtaining an ADU Permit in California

Navigating the permit application process for an Accessory Dwelling Unit (ADU) in the unincorporated areas of Los Angeles County involves specific steps and guidelines.

Getting Started

  • Determine Your Property’s Location: First, verify if your property is in the unincorporated area of Los Angeles County. You can do this by visiting Z-NET and entering your address or Assessor’s Parcel Number.
  • Understand the Rules: Familiarize yourself with the ADU regulations applicable to your property. A summary of these requirements is available on the Department of Regional Planning’s ADU webpage.

Design/Planning Approval for Single Family and Multifamily Properties

  • Consult with Regional Planning: If your property is in an unincorporated community, it’s advisable (though optional) to contact Regional Planning to understand specific ADU requirements for your property. You can visit a local office, email at, call at 213-974-6411, or sign up for a virtual appointment.
  • Hire an Architect or Designer: Engage a professional to develop a full set of architectural plans, including site plans, floor plans, and elevations, for submission to Regional Planning.
  • Application Submission: Submit a “Regional Planning – Base Application” through EPIC-LA. This should include a complete Land Use Application, architectural plans, and property photos. Detailed application materials and instructions are available on the “Accessory Dwelling Unit (ADU)” section of the Applications & Forms webpage.
  • Review Process: Once your application is deemed complete, you will be asked to pay the application fee. Post-payment, your plans will be reviewed, and the ADU will be approved or denied within 60 days. If corrections are needed, a deadline for resubmission will be provided. Delays on the 60-day deadline can be requested by the applicant.

Fees and Timeline

  • Ministerial Site Plan Review Fee: Ranges from $977 to $1193 (subject to change in March 2023).
  • Review Timeline: 60 days from the payment of the application fee.
  • Expiration: The approval is valid for 2 years, with a one-time extension of 1 year if requested by the applicant.
  • Approval and Next Steps: Once your ADU meets the requirements, Regional Planning will approve your plans and upload them to EPIC-LA. You will receive a link to download a copy of the approved plans, which you can use to apply for a building permit. Note that for Junior ADUs, a recorded covenant is required before plan approval.


This step-by-step guide tailored for unincorporated Los Angeles County provides a clear pathway for homeowners looking to develop ADUs.

By following these guidelines and utilizing the available resources, applicants can navigate the permit application process more effectively, ensuring compliance with local regulations and a smoother journey toward ADU completion.