In almost all cases, yes! ADUs are allowed in all residential and mixed-use zones and there is no minimum lot size. Homeowners can build both an ADU and a JADU on their property. However, if your property relies upon well water or a septic system, it depends on if those systems can support an ADU. (See below for details about multifamily properties.)

Homeowners can convert legally built structures (garage, barn, art studio, etc.) into an ADU. JADUs can be converted from an attached garage (but not detached). Check out this extensive guide to garage conversion ADUs from the Casita Coalition.

Homeowners can build both an ADU and JADU on their property.

Multi-unit properties can have multiple ADUs, depending on the type and other details of the project, but no JADUs.

The answer depends on the type of ADU and on your property. Look up your local ADU rules for more details on height, setbacks, and other rules.

Depending on the jurisdiction, new detached ADUs are typically limited to 850-1,200 square feet. Attached ADUs are typically limited to 50% of the pre-existing square-footage, or up to 800 square feet – whichever is more. Please review your local rules for more details.

According to state law, rules about setbacks, lot coverage, and open space requirements cannot restrict you from building an ADU of up to 800 square feet, as long as the ADU has rear/side setbacks of at least 4 feet. Front setbacks can also be adjusted, which means an ADU can be in a front yard – but only if rear or side placement isn’t possible.

Until January 1st, 2025, there is no requirement for homeowners to live on their property if it includes an ADU. However, 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. Some cities have removed parking requirements completely, but most require that ADUs one parking spot (which can be tandem, meaning directly behind another spot in the driveway), 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. Constructed along with new development.

In most cases, if the main house doesn't have fire sprinklers, then the ADU won't be required to install sprinklers. However, there are some exceptions to that rule where sprinklers may be required:

• If you build an ADU larger than 50% of the main house

• If you build over a garage

• If the ADU is farther than a certain distance from the street (typically 150') or closest fire hydrant (typically 400')

Check with your local Planning Department and Fire Marshall for exact details once you've developed your project further.

Utility connections can have significant design and scheduling impacts, so it’s good to think about them early on.

In general, it is less expensive to hook the ADU utilities to the main house, as opposed to building new water and sewer laterals to the mains in the street, or a second set of electrical lines from the pole. In some cases, particularly if your ADU is larger, over 750 square feet, you may be required to construct new connections. It is best to discuss this issue with your jurisdiction early in the design process.

Most homes will need to upgrade the main electrical panel and possibly electrical service to the property. This will involve both an electrician as well as coordinating with PG&E. Due to the demands on PG&E services, the upgrade process can take significant time and homeowners are often charged a $1,500 engineering fee for PG&E to begin the process. Additional fees may be charged depending on the condition and size of the electrical components running to the property.

Typical electrical and sewer upgrades for an ADU include a main electrical panel of at least 200 Amps and a sewer lateral of 4" for the whole property. If the existing lateral is 3" you may have to replace it with a 4" lateral to the street to handle the additional demand created by the ADU. Please consult with your building department for more information.

Water service may need to be upgraded as well, particularly when sprinklers are required such as when an ADU is built above a garage. The scale and cost of this work depends greatly on the age of the main house and the infrastructure provided by jurisdiction. It is important to determine if sprinklers will need to be planned for and get information on the water supply to your property early in the design and bidding process. This information is typically available from your Public Works or Engineering Department.