Chico Zoning and ADU Guide for Homeowners and Sellers

Last updated November 13, 2026. Reviewed by the Cash Home Buyers CA team. Information comes from City of Chico Planning and Building Division pages; sources are listed at the end.

Chico allows one detached ADU and one junior ADU (JADU) on a lot with an existing single-family home. Whether you want to build a unit or you are selling a property that already has one, here is how the city describes the rules.

Chico ADU rules at a glance

How do you permit an ADU in Chico?

The city lists three steps: confirm eligibility with the Planning Division, review the Chico ADU Development Standards, then prepare plans and submit them to the Building Division for building and sewer connection permits. Properties on septic or a well should check with Butte County Environmental Health at (530) 552-3880.

Size, placement and fee details sit in the development standards and the Master Fee Schedule, so confirm those with the city before you rely on any figure.

Can you legalize an unpermitted ADU in Chico?

The city says that under AB 2533, owners of unpermitted ADUs built before January 1, 2020 can apply for permits to legalize them. Owners may get a confidential third-party code inspection, request their assessor file, and then meet with the Building Official or Plans Examiner at 411 Main Street, Second Floor.

The unit must meet the health and safety standards in Health and Safety Code section 17920.3, and conditions that make it substandard must be corrected during the permit process.

How to sell a Chico house with an unpermitted unit

1. Find out what is on record. Ask the Building Division what permits exist for the address.
2. Decide whether to legalize. Legalization can add inspection and repair costs, so weigh it against selling as-is.
3. Disclose honestly. Known unpermitted work should be disclosed to buyers.
4. Compare offers. A cash buyer prices in the unit and the paperwork risk.

We buy Chico houses as they are. Read how selling a house as-is in Chico works, or see our Chico cash-offer process. For permit questions, see our Chico building permits guide.

Not sure what an unpermitted unit means for a sale? Call (424) 435-2326 or request a cash offer. There is no cost and no obligation.

The enforcement delay for older unpermitted ADUs

Chico’s Unpermitted ADUs page adds a second state rule to the legalization path. Under AB 2221, owners of unpermitted ADUs built before January 1, 2020 can request a five-year delay of enforcement against the violation, as long as the unit does not endanger health and safety.

The city says the request window runs until January 1, 2030, and that enforcement of the California Energy Code and CALGreen Code may be delayed for the five years. A delay is not a permit: the unit stays unpermitted until it is legalized.

The legalization steps, in order

1. Optionally get a confidential third-party code inspection from a licensed contractor or design professional to learn the unit’s condition and the likely scope of work.
2. Request a copy of your full assessor file, including notes, diagrams and assessments, as the legal owner.
3. Submit the assessment documents to the Building Official at 411 Main Street, Second Floor, or ask for a meeting with the Building Official or Plans Examiner.
4. Correct every condition that makes a building substandard under Health and Safety Code section 17920.3 as part of the permit process.
5. Obtain permits that meet the California Residential, Mechanical, Electrical, Plumbing and Fire Codes.

The page does not list fees, so ask the city for current figures before you budget.

What buyers and lenders ask about an ADU

• Is the unit permitted and signed off, or on an enforcement delay?
• Does it have its own entrance, kitchen and utilities, and is it rented?
• Does the listed square footage include it?
• Was the work done by a licensed contractor?

A unit that is not on record can be hard to appraise and finance. For the general rules on unpermitted improvements, see our California guide to selling as-is with unpermitted work.

Chico zoning and ADU FAQ

How many ADUs can a Chico lot have?

The city says one detached ADU and one JADU may be permitted on a lot with an existing single-family dwelling.

How big can a JADU be in Chico?

A JADU can be no more than 500 square feet and must be contained entirely within the existing single-family home.

Can I legalize an older unpermitted ADU?

The city says AB 2533 lets owners of unpermitted ADUs built before January 1, 2020 apply for permits, subject to health and safety standards.

What is the AB 2221 enforcement delay in Chico?

The city says owners of unpermitted ADUs built before January 1, 2020 can request a five-year delay of enforcement, until January 1, 2030, as long as the unit does not endanger health and safety.

Do I need an inspection before talking to the Building Official?

No. The city describes a confidential third-party code inspection as optional but encouraged.

Sources

• City of Chico: ADU/JADU Information
• City of Chico: Unpermitted ADUs

This guide is general information, not legal advice. ADU rules change; confirm requirements with the City of Chico.