Learn The Rules

→ Learn what you can build

→ Understand local ADU rules

Project Timeline

Learning the Rules is part of the Planning phase, which typically takes 1-3 months. Most ADU projects take 12-18 months to complete, but some extend to 24 months or more.

Learning The Rules FAQs

Here are a few of the most frequently asked questions about ADU rules. See the content below and our ADU Guidebook for more guidance, resources, and tips for all steps of the process.

In almost all cases, yes! ADUs and JADUs are allowed in all single-family and mixed-use zones. If residential buildings are allowed, ADUs are almost always allowed too (with limited exceptions for safety, traffic, and water). Homeowners can build both an ADU and a JADU on their property, and multifamily building owners can build one or two ADUs, depending on the type of project (but no JADUs).
Homeowners can convert legally built structures (garage, barn, art studio) into an ADU. JADUs can be converted from an attached garage (but not detached). If you demolish your garage or other enclosed structure and build an ADU in its place, the ADU can be in the same footprint if it’s the same size and height of the structure it’s replacing. You may need to provide replacement parking; check with local staff and see our Guidebook for more details.
If you plan on replacing a detached garage with an ADU, demolition permits, and public notice cannot be required if you have your ADU permit (unless it is in an architecturally and historically significant district). Check with local staff for other garage-related policies.
Note that garage conversion ADUs may require significant moisture barriers and other design elements in order to meet building codes.
ADUs and JADUs are allowed in all residential zones with limited exceptions for safety, traffic, and water.
Homeowners can build both an ADU and JADU on their property. Multifamily properties can have multiple ADUs, depending on the type and other details of the project. Talk to local staff or more information if interested in building ADUs on a multifamily property.
According to state law, rules about setbacks, lot coverage, and open space requirements cannot restrict you from building an 800 square foot ADU, as long as the ADU has setbacks of at least 4 feet and is not above 16 feet tall. Front setbacks also cannot restrict you from building an 800 square foot ADU, which means an ADU can be in a front yard – but only if rear or side placement isn’t possible.

According to state law, rules about setbacks, lot coverage, and open space requirements cannot restrict you from building an 800 square foot ADU, as long as the ADU has setbacks of at least 4 feet and is not above 16 feet tall. Front setbacks also cannot restrict you from building an 800 square foot ADU, which means an ADU can be in a front yard – but only if rear or side placement isn’t possible.
Your location may have requirements for homeowners to live on their property if it includes an ADU. Check with staff early to find out. JADU owners need to live in the primary unit or the JADU – and this will need to be recorded in a deed restriction for the property.
No. ADUs and JADUs cannot be rented for fewer than 30 days at a time.
Parking is much less of a concern than it used to be. JADUs do not require a parking spot. Local governments are prohibited from requiring additional parking for ADUs, unless it is: 1) within ½ mile walking distance to transit (including a ferry); 2) within an architecturally or historically significant district; 3) on-street parking permits are required and not provided to the occupant of the ADU; 4) located within one block of car-share access, or 5) built as part of a new home. Check with local staff to see if ADUs require additional parking.

Learning The Rules Key Resources

These guides and resources will help you learn the rules and what’s allowed on your property.

ADU GUIDEBOOK

A step-by-step guide to building an ADU in Alameda County.

Learn more →

LOCAL ADU RULES

A summary of ADU rules where you live.

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Explore more resources

Learning the Rules

Before you begin designing your ADU, you need to know what you’re allowed to build. We will help you navigate the state and local laws that apply to your property.

Keep in mind …

Understanding how all the local and state rules apply to your project can feel like a lot at first. Remember: local staff are there to help. Find your local planning staff contacts to ask all your ADU questions! You may also want to check out our Glossary to get familiar with key terms.

Learn about your property

First, you’ll gather some basic information about your property – what’s your Assessor’s Parcel Number (APN)? How big is your lot and how is it zoned? Use the County Assessor’s Parcel Viewer to find your Assessor’s Parcel Number (APN) and our Exercises to record some basic information on your property. Our Guidebook describes this step in more detail.

ADU Exercises

Learn what you can build

Next, you’ll need to understand what you can build on your property. Local and state laws will impact what is possible for your ADU, like its size and height and may include additional requirements about parking, fire safety, and more. See your Local ADU Rules to find out what applies and download our Guidebook for more detailed information about important ADU laws

Local ADU Rules

ADU Guidebook

Meet with local staff

One of the best things you can do is to talk to local staff early in the process about potential issues and rules that might apply. Most locations have a Planning or Permit Counter where you can ask questions without an appointment, or you can call or email. You may also be able to schedule an appointment. For contact information, see Local ADU Rules.

If you decide to move forward, it’s a good idea to return to meet with staff so they can review the final design and provide advice before submitting your application. While not required, this extra step can make sure you get your permit as soon as possible.

Use our Exercises to help plan your conversation and take notes. This is also a good time to contact any utility service providers (waste, sewer, gas, electricity, etc.) to confirm requirements, timelines, and fees.

Local ADU Rules

ADU Exercises