New Detached ADU in Pomona - Plans, Permits & Build, One Fixed Price

Fast, Reliable New Detached ADU Across Pomona

A new detached ADU on your Pomona property typically runs $220,000-$380,000 all-in, from the first site survey through final inspection, with the final figure hinging on whether your rear lot connects to city sewer or needs a county-approved septic system. We’re Ellery ADU Studio, and our New Detached ADU team has designed, permitted, and built over 900 ADUs since 2015. Dispatch and scheduling run from our Los Angeles office, but our crews serve Pomona directly. We know the difference between a Phillips Ranch lot that taps into city sewer and an open parcel near Ganesha Park that falls under county Environmental Health. That distinction changes your pad location, your grading plan, and your price. Call (840) 212-3065 to schedule your free estimate.

Call (840) 212-3065

Why Ellery ADU Studio Upland Is Pomona’s Preferred New Detached ADU Company

We’ve worked Pomona’s post-WWII neighborhoods long enough to know the patterns. The 1940s-1970s bungalows near Lincoln Park, the ranch homes off Mission Boulevard, the larger lots backing up to Phillips Ranch - each carries a different utility story and a different permitting path.

Our clients in Pomona receive the same documentation we provide everywhere: a written price before any work starts, per Haven Standard Clause 1; a documented photo record on every site visit; and the 365-Day Done Right Promise, backed in writing. If the finished ADU doesn’t match the permitted drawings, we make it right.

A live person answers our phones 24/7. No voicemail queue, no callback that doesn’t materialize. And if you already have a written estimate in hand, we’ll give you a Free Second Opinion on it.

We don’t guess at your lot conditions. We verify sewer service boundaries, test soil infiltration, and confirm electrical service capacity before we quote. In Pomona, where unpermitted backyard structures are common, that upfront legwork prevents the surprises that derail most projects.

Our New Detached ADU Services in Pomona

Custom Built ADU

A custom built ADU gives you full control over layout, materials, and finish level. In Pomona, we regularly design these for homeowners on 7,000-10,000+ sq ft lots who want a structure that matches their existing home’s character - James Hardie siding to complement a mid-century ranch, or a modern stucco finish for a newer build. The custom route also lets us address site-specific challenges: a wet corner that needs a French drain, a rear lot line that requires setback variance, or a slope that demands engineered grading. Every custom project includes the full permit set as our core deliverable, not an afterthought.

Prefab ADU Installation

Prefab ADU installation in Pomona makes sense when speed and predictability matter. We specify and coordinate systems from Abodu, Cover, and Dvele under the same single contract that covers design, permitting, and site work. The factory-built shell arrives on a flatbed, but the Pomona-specific work - the septic or sewer connection, the electrical trench from a likely-upgraded panel, the mini-split sized for Inland Valley heat - happens on-site and is scoped before you sign. Prefab doesn’t mean cookie-cutter. It means the envelope is built in a controlled environment while we handle the ground conditions your lot actually presents.

Modular ADU

Modular ADUs differ from prefab in their structural code and transport method. These units ship as fully completed modules, craned into place and stitched together on your foundation. In Pomona, modular makes sense for 1-bed and 2-bed ADUs where you want the efficiency of factory construction without sacrificing square footage. We coordinate the crane placement, the access path, and the utility rough-ins - all scoped in writing before work begins. The county septic review, if triggered, runs concurrent with module fabrication so we don’t lose weeks.

Studio ADU

A studio ADU, typically 350-450 sq ft, is the most common detached unit we build in Pomona for Cal Poly Pomona rental demand. These compact structures still require full utility service, proper insulation, and Title 24 compliance. We don’t spec coastal-LA thermal packages here. Pomona’s triple-digit summers and mid-30s winter nights demand a properly sized mini-split, R-19 walls minimum, and dual-pane windows. The studio format keeps the footprint tight, which helps with setback compliance on narrower lots near downtown or the Lincoln Park corridor.

1-Bed & 2-Bed ADU

1-bed and 2-bed detached ADUs in Pomona typically run 500-850 sq ft and command the strongest rental returns from student and staff housing demand. These sizes push closer to setback limits and utility capacity thresholds. We verify your existing service panel early - Pomona’s 60-100A originals rarely support a second dwelling without upgrade - and we confirm whether your rear lot line falls inside the sewer boundary or triggers county septic review. That single finding can shift the pad location by twenty feet and add $15,000-$30,000 to the project. We find out before we quote, not after.

Trusted Brands We Service in Pomona

We specify and coordinate prefab and modular systems from Abodu, Cover, and Dvele, and we regularly clad custom builds with James Hardie siding for durability in Pomona’s heat and Santa Ana wind cycles. Our relationships with these manufacturers mean we don’t mark up materials through a middleman - the product cost is the product cost, transparent in your written quote. For Pomona clients, this brand fluency matters because the right system for a sewer-tapped lot in Phillips Ranch differs from what’s optimal for a septic-dependent parcel near Ganesha Park. We match the product to the site, not the site to the product.

Common New Detached ADU Problems We See in Pomona Homes

• Sewer service boundary surprises. Pomona’s post-WWII lots frequently extend beyond the city’s sewer service area, especially on larger parcels near the northern and eastern edges. We verify this with the city before quoting. County septic approval adds a layer of perc testing and leach-field setbacks that city projects don’t face.
• Undersized electrical service. The 1940s-1970s housing stock throughout Pomona’s Lincoln Park and Mission Boulevard corridors typically carries 60-100A panels. A new detached ADU with electric heat, cooking, and laundry demands a dedicated subpanel, new meter, and often a 40-foot feeder trench. We scope this in the initial site survey.
• Thermal packages that fail Title 24. Specs that pass in coastal LA - single-pane windows, R-13 walls, undersized mini-splits - fail in Pomona’s Inland Valley heat pocket. We size for triple-digit afternoons and genuine heating loads, using dual-pane vinyl windows and R-19 minimum wall assemblies.
• Unpermitted existing structures. Pomona has a high density of informal backyard buildings and garage conversions. The building department typically requires these to be fully legalized or demolished before an ADU permit is approved. We handle the demo and remediation as a scoped line item, not a mid-project surprise.

Pricing for New Detached ADU in Pomona, CA

We Also Serve Cities Near Pomona

Our crews work throughout the eastern San Gabriel Valley and western Inland Empire. We also build New Detached ADU in Pomona neighboring cities: Diamond Bar, Montclair, Chino Hills, and Ontario. Each market carries its own permitting nuances and utility conditions, and we scope accordingly.

FAQs - New Detached ADU in Pomona