Why Ontario Homeowners Choose Ellery ADU Studio Ontario for ADU
Since opening our Ontario branch, we’ve brought the Haven Standard to homeowners across the Inland Empire who want an ADU designed, permitted, and built under one contract with one written price. Our team, led by Nadia Ellery, handles the full design-build process here in Ontario, from the first site survey through final inspection. The 900-plus ADUs completed under the Ellery name since 2015 share one trait: every one started with a flat price in writing and ended with a documented record of what was built.
6 Reasons We’re Ontario’s Top ADU Company
1. Eleven Years of ADU-Only Focus
Ellery ADU Studio was founded in 2015, the same year California’s statewide ADU law rewrote the rules and turned permitting speed into the real product. We’ve never built kitchens as a sideline or added ADUs to a general contracting menu. That focus means our drawings account for Ontario’s specific setback rules, our permit sets anticipate San Bernardino County’s checklist, and our crews know the difference between a standard foundation and the engineered slab Ontario’s expansive soils often require. When you’ve only done one thing for eleven years, you stop guessing.
2. A Reputation You Can Verify
We don’t ask you to trust us because we say we’re trustworthy. We point you to the documented record: photos of what we found, permit approval dates, and the written scope every homeowner signs before work starts. In Ontario, Chino, and Rancho Cucamonga, homeowners have used that documentation to sell homes, refinance, and settle disputes. A strong local reputation isn’t built on slogans; it’s built on evidence you can hold in your hand.
3. State-Licensed and Properly Insured
Every pro working under our name is required to hold the license and insurance California requires for ADU construction. That means a valid contractor license, active general liability, and workers’ compensation where applicable. We don’t publish license numbers because they change with renewals and can be verified directly through the CSLB, but we do provide proof of coverage with every written estimate. Clause 3 of the Haven Standard requires it.
4. Factory-Built and Site-Built Expertise
We design and permit both stick-built ADUs and factory-built units from brands including Abodu and Cover. That matters because an Abodu unit delivered to a sloped lot in Chino Hills needs different site prep than a Cover module set in flat Ontario. We don’t sell one brand; we match the product to your lot, your timeline, and your budget. When we specify James Hardie siding or a Tuff Shed structure, it’s because that material solves a specific problem on your specific property, not because we have a volume agreement to push.
5. The Price on the Page, Then in Writing
Clause 1 of the Haven Standard is “Have it in writing,” and it applies before anyone picks up a hammer. We publish price ranges for Ontario ADU construction because homeowners researching a six-figure decision deserve a number they can plan around. Your final written quote comes after a site visit, a soils check if needed, and a permit feasibility review. But you’ll never get a verbal estimate that doubles after the city asks for a retaining wall. Flat price, written scope, signed before we start.
6. The Haven Standard Guarantee
Every Ellery ADU Studio job is covered by our documented warranty and our satisfaction commitment. If something we built doesn’t match the drawings we permitted, we fix it. If a subcontractor’s work fails, we handle the callback. The guarantee is in writing because Clause 1 applies to promises too. We’ve found that homeowners in Montclair and Upland care less about how long we’ve been in business and more about what happens when something goes wrong. The Haven Standard tells them exactly that.
Our Promise to You
Here’s what happens if you’re not satisfied: you call the number below, a live coordinator connects you with our local team, and we document the issue with photos and a written response within two business days. If we missed something in scope, we complete it at our cost. If we damaged something, we repair or replace it. Our pricing transparency commitment means no change orders for work included in your signed scope, no “while we’re in here” upsells, and no surprises on the final invoice. Clause 5 of the Haven Standard is “No surprises,” and we treat it as a binding term, not a marketing phrase. Every homeowner in Ontario, Eastvale, and across our service area receives the same written warranty, the same documentation packet, and the same flat-price protection.
Frequently Asked Questions
Most ADU projects fail at the handoff between designer and builder. We’re a design-build studio, so the drawings, the permit set, and the construction are one contract with one price and one party responsible. Other companies may offer lower initial bids by separating design and build, but when the city rejects a foundation detail or the builder blames the architect, you’re stuck managing the dispute. We eliminate that gap. Call (951) 577-3472 to schedule your free estimate.
We document every phase with photos and written sign-offs, so “satisfied” isn’t subjective. If the built work doesn’t match the permitted drawings, we correct it. If a material fails within the warranty period, we replace it. Your written contract specifies the remedy for each category of issue before work begins. Call (951) 577-3472 for a copy of our standard warranty terms.
No. Our initial site visit and written estimate are free. We charge only when you sign a contract and we begin permit drawings. The estimate includes a price range based on your lot conditions, a timeline from permit submission to certificate of occupancy, and a list of variables that could affect the final number. Call (951) 577-3472 to schedule yours.
Yes. Every pro working under our name is required to hold the California contractor license and insurance coverage their role requires. We verify these credentials before anyone steps onto your property, and we provide proof of coverage with your written estimate. You can confirm any license through the Contractors State License Board at cslb.ca.gov. Call (951) 577-3472 if you’d like our license details for verification.
We schedule site visits across Ontario, Chino, Rancho Cucamonga, and surrounding cities based on current project load, typically within one to two weeks of your call. ADU construction is planned work, not emergency service, so we don’t promise same-day arrival. What we do promise is a named appointment window, a text when we’re en route, and a written summary within 24 hours of the visit. That’s Clause 2 of the Haven Standard: “Arrive on schedule.” Call (951) 577-3472 to book your site visit.
Written by Nadia Ellery, Owner at Ellery ADU Studio Ontario, serving Ontario, Chino, Eastvale, Montclair, Upland, Mira Loma, Rancho Cucamonga, Glen Avon, Claremont, Norco, Pomona, and Chino Hills.