How United Build Partners helps Fontana homeowners
We're not a construction company. United Build Partners is an ADU advisory and contractor-matching service: we start with a free review of your property and goals, help you understand what's realistic for your lot under Fontana's rules, and — when it's a good fit — connect you with up to three contractors in our network suited to your project type and neighborhood. From there, you compare proposals and decide who to work with; the licensed contractor you choose handles the actual design and construction.
ADU rules and permitting in Fontana
Like every California city, Fontana's ADU rules build on the statewide floor — ministerial review and a 60-day clock on complete applications (our California ADU laws guide covers the framework). Locally, ADUs and JADUs run through the Zoning and Development Code, and the Planning Department publishes an ADU Information Sheet covering the unit types.
What's specific to Fontana
- Homeowner-favorable size structure. Per the city, maximum ADU size is 50% of the main house's square footage OR 850 sq ft (studio/1-bed) / 1,000 sq ft (2+ bedrooms) — whichever is larger. On a big house, the 50% figure can exceed the flat caps many neighboring cities stop at.
- Standard ADU Plans program. Fontana maintains a Standard ADU Plans page under its AB 1332 program — pre-vetted designs intended to bypass the lengthier parts of permitting. Check the current catalog before assuming a design.
- Electronic permitting via FELP. The city's Fontana Electronic Land-management Portal (FELP) handles applications and records — the ADU process FAQ lives there too.
- Eligibility runs through zoning. Many residential properties qualify for an ADU and/or JADU, but eligibility depends on the parcel's zoning under the Zoning and Development Code — the first thing to confirm, and our zoning lookup guide shows how.
- Northern foothill parcels deserve an early check. Fontana climbs toward the San Gabriel foothills on its north side — parcels there may carry fire-hazard-zone construction requirements worth confirming with the city before budgeting.
Property and lot considerations
Fontana is one of the Inland Empire's largest and fastest-grown cities — established central neighborhoods with mature lots, big newer tracts to the south, and terrain rising toward the foothills in the north. The generous size rule matters most on larger homes, where 50% can support a genuinely full-sized second unit; on smaller homes the 850/1,000 floors do the work. Northern parcels should check fire-zone status early; southern tracts more often deal with HOA review — our HOA guide covers what associations can and can't require.
Common ADU types for Fontana homeowners
Fontana's larger lots make the detached ADU — including Standard Plan designs — the most common conversation, with garage conversions strong in the established core. A Junior ADU suits larger homes, and the generous size rule makes a two-bedroom configuration worth pricing where the house supports it — see our size and type comparisons.
Cost factors in Fontana
Inland Empire pricing generally runs below the coastal counties, and Fontana's flat central and southern lots keep site work predictable; foothill parcels can add fire-zone construction costs. Anchor against our cost guide and soft-cost categories, then get exact fees through FELP or the Planning counter.
Financing your Fontana ADU
Most homeowners fund ADU construction through a HELOC, cash-out refinance, a construction loan, or some combination — see our ADU financing overview and loan payment calculator for how each works. Financing options aren't generally city-specific, but a lender may consider your neighborhood and local rents when evaluating projected rental income as qualifying income.
How our process works
Frequently asked questions
The larger of: 50% of your main house's square footage, or 850 sq ft for a studio/one-bedroom (1,000 sq ft with two or more bedrooms). On larger homes the 50% path can exceed the flat caps common in neighboring cities — confirm your exact allowance with Planning at 909-350-6718.
Yes — the city publishes a Standard ADU Plans page under its AB 1332 program, with designs pre-vetted against local zoning and building rules. Under state law, a complete application using a preapproved plan must be acted on within 30 days.
Through FELP, the city's electronic land-management portal, where applications, records and the ADU process FAQ live. Confirm your parcel's zoning eligibility first — it's the gating question for ADU and JADU alike.