Frequently Asked Questions

Frequently Asked Questions

Should I upgrade my utility infrastructure when I share a water line?

If your house shares a water line with a neighbor, your property will need to be disconnected from the shared service and a new water service will need to be installed from the City main to the property to serve the primary residence, and the ADU. You may need to upsize your existing lateral water line to serve both your primary dwelling and the new ADU. The water lateral will need to be constructed per City standards and a new water meter for the ADU will need to be installed to accommodate for the increase in water service to your property. See water lateral schematic here.

Should I upgrade my utility infrastructure when I do not share a water line?

If your existing service is not shared and currently only serves your primary dwelling unit, you will likely still need to upsize your water service due to the size of water laterals constructed in older subdivisions. If this is the case, you will need to install a new lateral utility line to serve your primary dwelling and the new ADU to prevent negative impacts on your neighbor’s water service. A new water meter may also be required based on the Engineering Division’s review of your existing utility infrastructure. See water lateral schematic here.

What is the difference between an ADU and a Junior ADU?

There are many similarities and some differences between an ADU and JADU. Both JADUs and ADUs must be on a permanent foundation and have at least a kitchen facility and living room/bedroom that is separate from the primary dwelling unit. However, requirements for a JADU’s kitchen are more minimal than they are for an ADU. An ADU must have its own bathroom, while a JADU may have its own bathroom or share the bathroom in the primary dwelling unit. ADUs are allowed with multifamily or single-family dwellings, while JADUs are only allowed with single-family dwellings. ADUs may be conversions of existing space, additions or detached, while JADUs are only allowed as conversions of existing space. The maximum size of a JADU is 500 square feet, while the maximum size of an ADU is 850 square feet for studios and 1-bedroom units and 1,000 square feet for multi-bedroom units. JADUs can only be rented if the owner occupies the primary dwelling.

Can I convert my garage?

An existing garage can be converted into an ADU or JADU by making the garage space livable in accordance with applicable California Building Code standards, or by creating a unit on top of the garage. At baseline, a garage conversion ADU or JADU must include insulation, roofing, fireproofing, installation of fixtures, windows, and fire sprinklers where applicable. Consult the City Building Division to determine the requirements for building out an ADU or JADU in a garage.

What is the maximum allowable size?

In the City of Rohnert Park, ADUs cannot exceed 850 square feet for a studio or 1-bedroom unit and 1,000 square feet for a unit with two or more bedrooms. JADUs cannot exceed 500 square feet and are subject to some different regulations.

What is the maximum allowable lot coverage?

ADUs must adhere to the lot coverage requirements prescribed by the underlying zoning for the lot. Additionally, for ADUs larger than 800 square feet, the ADU together with the primary residence cannot cover more than 50 percent of the lot area.  However, ADUs of 800 square feet or less are not subject to maximum lot coverage requirements. Internal conversions are exempt from lot coverage requirements.

What are the setback requirements?

Setback requirements vary mainly based on whether an ADU or JADU is built entirely within an existing building or if a new structure or new square footage is part of the ADU or JADU project. See the Development Standards page for setback requirements for each type of ADU.

Is there a required number of bedrooms?

An ADU or JADU may have up to the maximum number of bedrooms that will fit within the square footage, as allowed by the Building Code. Typically, ADUs or JADUs in Rohnert Park only have one bedroom or are studios.

What zones allow ADUs and Junior ADUs?

ADUs can be built by-right in any zone that allows residential uses. ADUs are not subject to lot size requirements, density limitations, or growth-control measures. JADUs can be built within an existing or proposed single-family dwelling by-right in any zone that allows single-family residential uses. This is subject to different rules and requirements depending on the zone. See Zoning and Allowed ADU Types.

What is the maximum height allowed?

A detached ADU may be up to 16 feet in height. An attached ADU that is added on top of an existing structure may add an additional 16 feet of height to the structure. The maximum height of an ADU or JADU created by the conversion of existing floor area would be the same as the maximum height permitted for the existing structure.

Can I legalize an unpermitted ADU or Junior ADU?

Yes, legalizing existing, unpermitted ADUs or JADUs is encouraged! Contact the Planning Division for more information about requirements for getting an unpermitted ADU legalized.

What are the owner occupancy requirements?

Owner occupancy requirements depend on the type of ADU. If you are building a JADU, then you have to live on your property. You do not have to live on your property to own and operate an ADU.

What are the parking space requirements?

No parking is required to be added or designated for an ADU or JADU.

How do I find my zoning information?

The City maintains a Zoning Map, which designates zoning districts throughout the City.  In addition, zoning district information explaining your setback and site coverage requirements are in the “Development Standards” section of the City’s Zoning Code. These requirements can be found in Section 17.10.020, Development Standards Table. See Zoning and Allowed ADU Types.

How do I get help designing an ADU or Junior ADU?

Begin by looking for a design professional who can help design your ADU. A design professional could be an architect, designer, design/build firm, or modular/prefabrication company. Once you have met with the design professional and shown them your design ideas and lot limitations, they can help draw up preliminary designs for your ADU or JADU. Check out the Resources page for more on working with professionals and design resources.

What is the timeline for ADU or Junior ADU development?

Most projects take one to two years to complete, but there are different aspects of the project that can change that timeline. Typically, it takes owners up to three months to hire the key players on their team, and the following one to six months developing plans and submitting complete ADU or JADU Planning and Building applications. The number of rounds of review and your team’s timely response to City comments will dictate how quickly the team can start construction. Traditional construction of an ADU or JADU will take between six months and one year.

Do Electrical Panels and Sub-Panels Need to be Accessible?

Electrical panels and sub-panels, also known as circuit breaker panels/sub-panels or service panels/sub-panels, must be accessible to the ADU and JADU. Problems can arise if the ADU or JADU tenant cannot access the electrical panel or sub-panel when a circuit break occurs. Electrical sub-panels serve as a waypoint between the main electric panel and branch circuits further down the electrical line and can be installed in a secondary location on your property to be accessible to the ADU or JADU.

Does the City collect impact fees for ADU and Junior ADU development?

No, the City does not collect impact fees for any type of ADU or JADU.

Can I get more time to fix an issue with my ADU identified by Code Enforcement?

You can request a delay in code enforcement, subject to certain findings. See Section 17.07.020.X.12 of the City’s Municipal Code for further details.

What if I have more questions?

The Planning Division and the Building Division are available to answer your questions.

ADU Navigation Links

Planning Division

City of Rohnert Park Development Services – Planning Division
130 Avram Ave.
Rohnert Park, CA 94928
Phone: (707) 588-2231
Email: [email protected]

Building Division

City of Rohnert Park Development Services – Building Division
130 Avram Ave.
Rohnert Park, CA 94928
Phone: (707) 588-2240
Email: [email protected]