An accessory dwelling unit (ADU) is a secondary residential unit on the same lot as the primary residence. There are various types of ADUs, each designed to suit different needs and spaces.  Bay Area has specific ADU regulations, ensuring the units are safe and meet the city’s housing standards.

Are you considering building an ADU in Bay Area? If so, you must comprehensively understand the city’s regulations and requirements for accessory dwelling units (ADUs). This blog post will provide a detailed overview of ADUs, including the different types, their benefits, and the specific regulations that apply to them in Bay Area.

Bay Area ADU Requirements

Understanding the Permitting Process for Bay Area ADUs

Before constructing an ADU in Bay Area, you must navigate the city’s complex permitting process. This process includes understanding zoning requirements, submitting detailed site plans, and completing various application forms. It’s essential to approach this process with patience and thoroughness, as any missteps could lead to delays, extra costs, or denial of your application. In this section, we’ll walk you through the steps you need to take to obtain a permit for your ADU in Bay Area.

Zoning Requirements for Bay Area ADUs

The first step in the permitting process is determining if your property is eligible for an ADU. In Bay Area, specific zoning requirements must be met, including lot size and location restrictions. For example, the maximum size of an ADU can be at most 50 percent of the primary residence or 1,200 square feet, whichever is less. Additionally, ADUs must be located within the rear half of the lot and cannot be built on slopes greater than 20 percent.

Before moving forward with your ADU project with DevArt8 Construction, it’s crucial to consult with city officials or a professional ADU builder to ensure your property meets all zoning requirements.

Benefits of ADUs

Affordable housing option

It offers an affordable housing option for renters, especially in high-cost areas like Bay Area. Apartments are typically more affordable than single-family homes, allowing renters to live in desirable neighborhoods.

Rental income

ADUs allow homeowners to generate additional rental income, which can help offset the cost of their mortgage and property taxes.

Moreover, rental income from ADUs can improve homeowners’ financial stability. They provide a consistent source of income that can be used to fund home improvements, retirement, or other financial goals. This income potential makes it an attractive and practical investment for homeowners in Bay Area.

Flexibility for family members

These projects allow homeowners to have family members live nearby while maintaining privacy and independence. This mainly benefits aging parents or adult children who may need assistance but prefer living separately.

Increase in property value

Adding a dwelling unit can significantly increase a property’s value. It also gives homeowners more options for selling their homes in the future. Prospective buyers often view ADUs as attractive, given their potential for rental income or additional living space. Consequently, homeowners in Bay Area who add an ADU may find their property value appreciably increased when selling.

Increased property value

Investing in ADU construction can significantly boost the value of your property. Prospective buyers often view these projects as attractive features, given their potential for rental income or additional living space. Consequently, homeowners in Bay Area who add an ADU may find their property value appreciably increased when they sell.

Housing for relatives, friends, and caretakers

ADUs can provide a convenient housing option for relatives, friends, or caretakers who may need a place to stay temporarily. This allows homeowners to offer support and assistance to their loved ones without compromising their living space or privacy.

Bay Area ADU Regulations

Navigating Bay Area ADU laws and regulations is crucial for homeowners considering the addition of an ADU to their property. These laws govern various aspects of ADU construction, from size restrictions to parking requirements. Let’s delve into the specific regulations that apply in Bay Area, providing you with a comprehensive understanding of what to expect when undertaking an ADU project.

Minimum lot size

There is no minimum lot size requirement for ADUs in Bay Area, meaning homeowners with smaller properties can still maximize their living space through these projects. However, size restrictions on the ADU itself still apply and vary depending on the type of unit being built. Owners must consult the city’s planning department to ensure their proposed dwelling unit meets accepted size parameters.

Allowed locations

In Bay Area, accessory dwelling units can be established in various zoning districts, including single-family, multi-family, mixed-use, and commercial communities. Locations are subject to restrictions to preserve the neighborhood’s aesthetics and ensure the availability of essential services like utilities and parking.

ADU placement should also adhere to the setback rules, with minimum distances required from property lines. Homeowners must verify their property’s zoning and review specific regulations with the city planning department to ensure compliance with all local requirements.

Maximum square footage

In Bay Area, the maximum square footage for an ADU is determined by its type and the size of the lot. For detached projects, the full allowable size is 1,200 square feet. For attached dwelling units or those created within the existing space of the primary residence, the maximum size is 50% of the current primary dwelling or 1,200 square feet, whichever is less.

Junior dwelling units are limited to a maximum of 500 square feet. Considering these square footage limitations when planning your ADU project is crucial to ensure compliance with the requirements and avoid potential regulatory issues.

Number of ADUs allowed

Bay Area ADU regulations permit homeowners to construct up to two accessory dwelling units on their property: one detached and one junior within the primary residence. However, it’s crucial to note that junior units are only permitted if constructed within the existing walls of a single-family home.

Homeowners must understand these limitations to ensure their plans align with the ADU requirements. Non-compliance could lead to penalties and make future property sales more challenging. Homeowners are encouraged to consult with the city’s planning department to ensure their project complies with all local regulations.


Parking regulations for ADUs in Bay Area ensure that adding these units does not impact street parking availability for existing residents. Generally, one off-street parking spot is required for each dwelling unit. However, there are exceptions to this rule; for instance, if the ADU is located within a half-mile of public transit, no additional parking is required.

Furthermore, suppose the project is created within the existing space of the primary home, such as a converted garage, basement, or the like. In that case, no additional parking spaces need to be provided. Nevertheless, consulting with the Bay Area city planning department is crucial to understanding and complying with the project’s parking requirements.

Maximum height

The maximum height of an accessory dwelling unit in Bay Area is strictly regulated to maintain the aesthetic integrity of local neighborhoods. For a detached unit, the full allowable size is 16 feet. However, the property’s zoning can influence this height, the lot’s slope, and other factors.

Furthermore, the height should be measured from the ground level to the structure’s highest point, including the roof. Homeowners are highly recommended to consult with the Bay Area city planning department to ensure their ADU design complies with these height restrictions as part of the overall requirements.

Minimum setbacks

In Bay Area, regulations mandate specific setback rules for ADUs to preserve neighbourhood character and comply with safety codes. Generally, a setback of 4 feet from the side and rear property lines is required for detached dwelling units. However, units created within an existing structure or attached to the primary residence may not require additional setbacks.

Please contact us if you still have questions or need further clarification about the Bay Area ADU requirements. Our team of experts is eager to assist you. You can reach us at +1-669-293-1126.

In Conclusion

Understanding the Bay Area ADU requirements is integral to any homeowner considering building an accessory dwelling unit (ADU). From allowed locations to parking regulations, these guidelines maintain our communities’ aesthetic and functional harmony. While ADUs offer significant benefits, such as creating additional living space or income stream, it’s crucial to understand and comply with local regulations thoroughly.