Fast, Reliable New Detached ADU Across Pomona
A new detached ADU in Pomona typically runs $165,000-$340,000 all-in, from permit-ready drawings through final inspection, depending on whether you choose a custom stick-built structure, a prefab system, or a modular unit. Ellery ADU Studio has designed, permitted, and built more than 900 ADUs since 2015, and our crews serve Pomona directly from our Los Angeles office, with scheduling and site visits coordinated for this market. If you’re on a 7,000-10,000 sq ft lot in the Lincoln Park, Wilton Heights, or Westmont areas - or anywhere else in Pomona’s 91766, 91767, or 91768 zip codes - we’ll bring a written price to your first meeting, not a callback promise. Call (909) 506-1121 to schedule your free estimate.
Why Ellery ADU Studio Rancho Cucamonga Is Pomona’s Preferred New Detached ADU Company
Pomona homeowners know the difference between a contractor who hands off permit headaches and a design-build studio that owns them. We’ve worked the alley-facing garage layouts unique to Pomona’s central flats, coordinated addressing and service separation with Pomona Building & Safety, and sized mini-split systems for the inland valley heat that coastal LA builders consistently underestimate.
Our reputation here is built on documentation, not slogans. Every project receives a written price before any work starts - Haven Standard, Clause 1 - plus a documented photo record on every site visit and a 365-Day Done Right Promise backed in writing. A live person answers our phones 24/7. No voicemail queue. No callback that doesn’t materialize.
We also offer a Free Second Opinion on any written estimate already in your hands. If another Pomona ADU company has quoted you, bring it in. We’ll review the scope, the allowances, and the permit strategy - in writing, at no charge.
Our New Detached ADU Services in Pomona
Custom Built ADU
A custom built ADU in Pomona gives you full control over layout, materials, and finish level - critical on older lots where the existing garage doesn’t align with modern setback requirements or where the alley access creates unusual buildable geometry. We design the permit set in-house, build from our own drawings, and hold one contract for the entire project. No designer-builder blame gap. In Pomona, where 1940s-1960s tract homes sit on some of western LA County’s largest lots, a custom detached ADU often makes more sense than squeezing into an existing structure.
Prefab ADU Installation
Prefab ADU installation in Pomona works well for homeowners who want speed and price certainty. We specify and coordinate systems from Plant Prefab, Boxabl, and Tuff Shed - each engineered for California’s seismic and energy codes, then adapted to your specific Pomona lot conditions. The inland valley heat load means we never drop in a standard HVAC package; we size the mini-split for 105°F+ afternoons and the radiant gain from un-shaded concrete and stucco. Our New Detached ADU team handles the full coordination: foundation, utility tie-in, and final inspection.
Modular ADU
Modular ADU construction in Pomona delivers factory-built precision with site-specific adaptation. We work with modular brands including Boxabl and Plant Prefab, then manage the crane set, foundation integration, and utility connections on your Pomona property. The key local variable is the alley-facing entry and separate service meter - advantages unique to Pomona’s rear-alley blocks - which must be coordinated with Building & Safety and the water/power departments before the module arrives, not after.
Studio ADU & 1-Bed & 2-Bed ADU
Studio ADU layouts in Pomona are popular with Cal Poly Pomona’s 27,000+ students as tenants, while 1-bed and 2-bed configurations command higher rents and longer lease terms. We size every unit to the actual rental market, not a generic floor plan. A studio ADU on a Pomona alley block with its own address and separate meter rents at a premium to a converted garage with shared utilities. We model this in the design phase, not discover it after permit close.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Before
AfterTrusted Brands We Service in Pomona
Ellery ADU Studio specifies and coordinates prefab and modular systems from Plant Prefab, Tuff Shed, and James Hardie - brands whose California-approved assemblies we adapt to Pomona’s specific inland valley conditions. James Hardie fiber-cement siding, for instance, handles the thermal cycling and UV exposure of Pomona’s 105°F+ summers better than vinyl or wood alternatives. We don’t just order a catalog unit; we specify the cladding, the insulation package, and the HVAC sizing for your specific lot orientation and shading. Parts and replacement materials are stocked regionally, so warranty work or finish adjustments don’t trigger long lead times.
Common New Detached ADU Problems We See in Pomona Homes
- 60-amp service and uninspected framing blocking Title 24 sign-off. Pomona’s detached garages from the 1920s-1965 era almost never meet habitable-space standards. We inspect first, document the deficiencies, and price the electrical upgrade and framing remediation in writing before permit submission - not after walls are open.
- Mini-splits sized for coastal LA, not inland valley heat. A unit rated for mild Santa Monica summers will fail in Pomona’s July afternoons. We calculate radiant heat load from concrete and stucco, then specify equipment that holds setpoint when the thermometer hits 105°F+.
- Alley access and separate addressing coordinated too late. The rear-alley layout that makes Pomona garage ADUs so rentable also requires early permit-intake coordination with Building & Safety and utility departments. We handle this in pre-application, not as a change order after construction starts.
- Surprise structural and waterproofing failures inside opened walls. On a 1950s wood-frame tract house off a rear-alley block in the Wilton Heights area, our crew opened the detached garage for a New Detached ADU and found the classic Pomona stack: 60-amp service, no insulation, a slab-on-grade floor, and stucco-and-concrete radiant load. We pulled the permit first, documented the undersized wiring, the framing, and the failed waterproofing in the inspection report, then priced every surprise in writing for the owner’s approval before we touched the walls - converting it into a permitted one-bed with a mini-split sized for the inland valley heat and its own alley address.
Pricing for New Detached ADU in Pomona, CA
A studio ADU in Pomona typically runs $165,000-$220,000 all-in. A 1-bedroom detached ADU runs $210,000-$280,000. A 2-bedroom unit runs $260,000-$340,000. These ranges include our in-house permit set, construction, and final inspection - one contract, one written price, per Haven Standard Clause 1.
Pomona’s inland valley climate adds meaningful cost compared to coastal builds: Title 24 requires HVAC as baseline, not upgrade, and the equipment must be upsized for radiant heat load. Foundation work varies by slope and soil conditions common in the foothill-adjacent neighborhoods near Phillips Ranch. Alley-facing entry and separate meter coordination adds permit complexity but returns rental premium.
Every project receives a written line-item quote before any work begins. No “call for pricing.” No range that widens after sign-off. Call (909) 506-1121 for your free estimate.
We Also Serve Cities Near Pomona
Our crews work throughout the Pomona Valley and western San Bernardino County. We also serve Pomona neighbors in Montclair, Claremont, La Verne, and San Dimas - each with its own zoning quirks, but all within the same single-contract design-build model and the same written-price guarantee.
Serving Pomona, CA - Our Local Coverage Area
We’re based in the Pomona area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - New Detached ADU in Pomona
HVAC is code-required baseline in Pomona’s inland valley climate, not an optional upgrade, and the mini-split must be upsized for 105°F+ afternoons and radiant heat from un-shaded concrete and stucco. Coastal LA builds often skip cooling entirely or specify smaller equipment. Foundation and insulation requirements also run stricter for the thermal cycling Pomona experiences. Call (909) 506-1121 for a written quote that accounts for your specific lot conditions.
Yes, and this is one of Pomona’s unique advantages. Many central flat blocks were platted with rear service alleys, allowing a converted garage ADU to take its own alley-facing entry, separate utility meter location, and even a distinct street address. This requires early coordination with Pomona Building & Safety and the water/power departments during permit intake - not after construction starts - and we handle this in our pre-application phase. Call (909) 506-1121 to discuss whether your lot qualifies.
The classic Pomona stack: 60-amp electrical service, zero insulation, slab-on-grade floors, and failed waterproofing in 1920-1965 wood-frame construction. Once walls open, the permit triggers code upgrades that weren’t visible during a surface inspection. We catch these in our pre-construction inspection, document them with photos, and price every item in writing for your approval before we touch the walls - Haven Standard, Clause 5 (No Surprises). Call (909) 506-1121 to schedule the inspection.
We don’t let them become surprises. Our pre-construction inspection documents existing conditions before permit submission. The contract includes written allowances for likely findings based on Pomona’s housing stock age and type. If we find something outside those allowances, we stop, photograph, price the remedy in writing, and obtain your signed approval before proceeding. No door-side upsells. No scope creep. This is Clause 5 of The Haven Standard, applied on every project. Call (909) 506-1121 to review how this works on your property.
Pomona combines three factors rare in LA County: large lots (7,000-10,000 sq ft), existing detached garages with alley access, and sustained rental demand from Cal Poly Pomona’s 27,000+ students. A detached ADU with its own address and separate meters commands premium rent and simpler tenancy than a shared-utility conversion. The ROI calculation here outperforms most coastal LA markets where land costs and zoning restrictions compress returns. Call (909) 506-1121 for a free estimate and rental pro forma.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Pomona since 2015.