Fast, Reliable Garage Conversion ADU Across Pomona
A garage conversion ADU in Pomona typically runs $85,000-$165,000 all-in, from measured drawings through final inspection, with detached garage conversions on the higher end due to slab reinforcement and electrical service upgrades that most 1920s-1950s Pomona homes require. We’re the Garage Conversion ADU team at Ellery ADU Studio, and our crews serve Pomona from our Los Angeles office with same-week site visits and written quotes before any work begins. If you’re in Lincoln Park, Mayfair, or the Ganesha Hills area, we know the slab conditions, the panel situations, and the permit path your garage conversion will face.
Why Ellery ADU Studio Ontario Is Pomona’s Preferred Garage Conversion ADU Company
We’ve designed, permitted, and built garage conversion ADUs across Pomona’s 1920s-1950s housing stock since 2015, the year California’s ADU laws shifted. Our 900+ ADU portfolio includes dozens of Pomona projects, from detached garage conversions near Cal Poly Pomona to carport-to-JADU builds in the Mayfair Historic District. Every project carries a written price before work starts, per Haven Standard Clause 1, and our 365-Day Done Right Promise is backed in writing before the first permit is pulled.
Pomona homeowners call us because we build the slab reinforcement and electrical service upgrade into our baseline bid, not as a mid-project surprise. Our documented photo record shows you what we found, what we did, and what it cost, with no summary of how it felt. A live person answers our phones 24/7 at (951) 577-3472, and we offer a Free Second Opinion on any written estimate already in hand.
Our Garage Conversion ADU in Pomona work is coordinated locally, with crews who understand that Pomona’s inland valley heat profile demands different material specs than coastal LA or even mid-county projects.
Our Garage Conversion ADU Services in Pomona
Detached Garage Conversion
Pomona’s large-lot Craftsman bungalows and postwar ranches often include detached single-car garages from the 1920s-1950s with 4-inch unreinforced slabs and 60A or 100A service panels. We treat the slab reinforcement and 200A panel upgrade as baseline scope, not change orders. A typical detached garage conversion in Pomona runs $110,000-$165,000 all-in, including the structural, electrical, and permit work. We specify 26-gauge Galvalume roofing with hot-dip galvanized fasteners and low-e 366 glazing on west-facing walls to handle Pomona’s brutal late-afternoon heat gain.
Garage Partition & Bathroom Add
Many Pomona homeowners want to keep half the garage for storage and convert the other half to a studio with bathroom. This requires careful plumbing layout, since Pomona’s older sewer laterals are often clay or cast iron that needs spot repair before a new bathroom wet vent can tie in. We handle the sewer camera inspection and any lateral repair in our single contract. Garage partition projects in Pomona typically run $85,000-$125,000, depending on whether the existing slab can support the new bathroom load or needs reinforcement.
Garage JADU
A Junior ADU conversion of an attached or detached garage in Pomona must stay under 500 square feet and share utilities with the primary residence, which can sidestep the full 200A service upgrade if the main panel has modest headroom. We verify panel capacity during our first site visit, not during rough-in. JADU conversions work well for homeowners near Cal Poly Pomona who want to rent to students or staff without the full ADU investment. Typical Pomona garage JADU projects run $75,000-$115,000.
Attached Garage Conversion
Attached garages in Pomona’s postwar ranch tracts often have better slab conditions than detached structures from the same era, but they share a wall with the main house, which means fire separation and sound attenuation requirements under the California Building Code. We handle the fire-rated assembly design and inspection sign-off as part of our permit set. Attached conversions in Pomona typically run $90,000-$140,000.
Carport Conversion
Pomona’s mild winters mean many older homes still have original carports that never enclosed. Converting a carport to an ADU requires a full foundation, wall assembly, and roof structure, essentially building new while preserving the existing footprint. We specify James Hardie fiber-cement siding on carport conversions for UV resistance in Pomona’s inland heat. These projects typically run $100,000-$155,000.
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.
Trusted Brands We Service in Pomona
Ellery ADU Studio specifies and coordinates prefab and modular systems from Abodu, Cover, and Dvele within our single-contract design-build model, though most Pomona garage conversions are stick-built to match the existing home’s character. For cladding and roofing on Pomona’s UV-intense sites, we source James Hardie fiber-cement products with ColorPlus Technology finishes rated for high-heat exposure, and we keep hot-dip galvanized fastener stock on hand for local crews. Every material spec is documented in your permit set and written scope before construction starts.
Common Garage Conversion ADU Problems We See in Pomona Homes
- Standard asphalt shingles and aluminum fasteners fail within 8-10 years on Pomona’s west-facing roofs where peak UV drives shingle blistering and fastener back-out. We specify 26-gauge Galvalume standing-seam roofing with hot-dip galvanized fasteners instead, at a material cost premium of roughly 15% that pays back in avoided re-roofing.
- Unreinforced 4-inch garage slabs crack under the new dead load of a bathroom and kitchenette, requiring costly epoxy injection or partial re-pour after framing is already up. We test slab thickness and rebar presence during our first site visit and build reinforcement or full replacement into the baseline bid.
- Original 60A/100A panels with no capacity headroom force a full 200A service upgrade and new subpanel, discovered after rough-in begins on projects where the builder didn’t verify upfront. We require a licensed electrician’s load calculation before we sign any Pomona contract, and we price the upgrade from day one.
- Coastal-grade vinyl windows and standard low-e coatings degrade prematurely in Pomona’s triple-digit heat and intense UV. We specify low-e 366 glazing with vinyl frames rated for 180°F surface temperatures, or aluminum-clad wood for higher-end projects.
Pricing for Garage Conversion ADU in Pomona, CA
Garage conversion ADUs in Pomona typically run $85,000-$165,000 all-in, drawings through final inspection, with the final figure driven by four factors we verify before quoting: slab condition and reinforcement needs, electrical service capacity and any required panel upgrade, plumbing tie-in distance and sewer lateral condition, and whether the project qualifies as a JADU or full ADU under state law. Detached conversions with slab and panel work sit at the top of this range; attached garage JADUs with shared utilities and no major electrical work sit at the bottom.
Every Ellery ADU Studio project is quoted with a written price before any work begins, per Haven Standard Clause 1. No “call for a quote” - we inspect, we document, we write it down. Call (951) 577-3472 to schedule your free estimate.
We Also Serve Cities Near Pomona
Our crews work throughout the San Gabriel Valley and Inland Empire, including Diamond Bar, Montclair, Chino Hills, and Claremont. Each city’s building department has its own inspection schedule and material preferences, and we adjust our permit sets accordingly. If you’re near the Pomona border in any of these cities, the same single-contract model and written pricing apply.
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 - Garage Conversion ADU in Pomona
Probably not without reinforcement. Most 1940s detached garages in Pomona sit on 4-inch unreinforced slabs that weren’t designed for the dead load of a bathroom, kitchenette, and habitable finish. We test thickness and rebar presence during our first site visit, and if the slab needs work, we build it into the written quote from the start. Call (951) 577-3472 for an exact assessment - estimates are free.
Pomona’s older housing stock skews heavily toward original 60A and 100A service panels installed before modern electrical loads, and a garage conversion ADU adds a full second dwelling unit with kitchen, bathroom, and HVAC. Claremont and Chino Hills have more 1970s+ housing with 200A panels already in place. We verify panel capacity with a licensed electrician’s load calculation before quoting, so the upgrade price is in your written scope, not a mid-project surprise. Call (951) 577-3472 to schedule.
We specify 26-gauge Galvalume standing-seam roofing with hot-dip galvanized fasteners, not standard asphalt shingles with aluminum fasteners that blister and back out within 8-10 years in Pomona’s UV intensity. The Galvalume spec adds roughly 15% to roofing material cost but eliminates a full re-roof within a decade. For wall cladding, we use James Hardie fiber-cement with ColorPlus Technology rated for high-heat exposure. Your written scope lists every material by manufacturer and grade.
Yes. West-facing walls in Pomona take the full brunt of late-afternoon sun in July and August, when triple-digit temperatures are routine and inland heat peaks after 4 p.m. We specify low-e 366 glazing with a 0.25 SHGC or better on west-facing windows and doors, and we design roof overhangs or exterior shading where the architecture allows. Without this spec, cooling loads spike and the mini-split runs continuously. Call (951) 577-3472 for a site-specific glazing plan.
Yes, if the finished space stays under 500 square feet and shares utilities with the primary residence. A JADU classification can reduce permit fees and may avoid a full 200A service upgrade if the main panel has modest headroom. We evaluate JADU feasibility during our first site visit and document the classification in your permit set. Many Cal Poly Pomona-area homeowners choose this path for student or staff rentals. Call (951) 577-3472 to see if your garage qualifies.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Pomona since 2015.