Fontana Zoning and ADU Guide for Homeowners and Sellers

Last updated November 13, 2026. Reviewed by the Cash Home Buyers CA team. Information comes from the City of Fontana Planning Division and its ADU information sheet; sources are listed at the end.

Fontana publishes an ADU information sheet that sets out different rules for junior ADUs, conversions, new detached units and multifamily properties, and its Zoning and Development Code controls which lots are eligible. If you own a house with a backyard unit or converted garage, or you are thinking of adding one, start with your zoning.

Fontana ADU rules at a glance

How do I find my Fontana zoning?

The city says you can look up your zoning online. On the city website choose Government, then Planning, then Zoning, General Plan Information and Maps, and open the Zoning and General Plan Land Use Interactive Map.

Enter the address and choose Zoning for the district, General Plan for land use, or Specific Plan to see whether the property sits in one of the city’s specific plan areas.

If it does, the city asks you to call the Planning Department at (909) 350-6718 for more specific zoning information.

What do Fontana’s ADU rules say for multifamily lots?

According to the city’s information sheet, a property with new multifamily construction can have two detached ADUs, and a property with existing multifamily can have up to eight detached ADUs, not exceeding the number of existing units.

Detached units are limited to 850 square feet, or 1,000 square feet for units with more than one bedroom. Converted ADUs in multifamily buildings cannot exceed 25 percent of the total units on site, with at least one allowed, and they have no maximum size.

Parking is one space per ADU unless an exemption in the Fontana Municipal Code applies.

Fontana also offers Standard ADU Plans, pre-approved designs already checked against local zoning and building rules. Ask Planning whether a standard plan fits your lot.

How zoning and ADUs affect selling a house in Fontana

A converted garage, a backyard cottage or a rented room is valuable only if buyers and lenders can see it was legally built. In California, sellers generally must disclose known problems, including work you know was done without a permit.

A unit that does not appear in permit records may be treated as unpermitted living space, and an appraiser or lender may refuse to count it. The usual options are to permit it after the fact, remove it, lower the price, or sell to a buyer who accepts the risk.

How to sell a Fontana house with an unpermitted unit or zoning problem

1. Check your zoning. Use the city’s interactive zoning map.
2. Compare the unit to the rules. Size, setbacks and parking for its type, per the city’s sheet.
3. Call Planning. Ask what would be needed to legalize it at (909) 350-6718.
4. Compare options. Legalize, discount, or sell as-is to a cash buyer.

We buy Fontana houses as they are. Read how selling a house as-is in Fontana works, or see our Fontana cash-offer process. If the house has been cited, read our Fontana code enforcement guide.

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

Fontana zoning and ADU FAQ

How big can a junior ADU be in Fontana?

The city’s information sheet lists 500 square feet as the maximum, with no parking required and owner occupancy required when the bathroom is shared.

Can I convert a garage to an ADU in Fontana?

The sheet lists conversions of existing space in a single-family home with no maximum size. Confirm the details of your lot with Planning at (909) 350-6718.

How do I check my zoning in Fontana?

Use the Zoning and General Plan Land Use Interactive Map on the city website, or call Planning if the lot is in a specific plan area.

Can I sell a Fontana house with an unpermitted unit?

Yes, with proper disclosure. A cash buyer can purchase it as-is and account for the risk in the offer.

Sources

• City of Fontana: ADU Information Sheet
• City of Fontana: Planning Applications, Subdivisions and Zoning FAQ
• City of Fontana: Standard ADU Plans

This guide is general information, not legal advice. ADU and zoning rules change often; confirm requirements with the City of Fontana Planning Division.