Fast, Reliable Garage Conversion ADU Across Pomona
A garage conversion ADU in Pomona typically runs $95,000-$165,000 all-in, from measured drawings through final inspection, and most projects reach certificate of occupancy in 6-10 months depending on Pomona Building & Safety’s current intake queue. We’re Ellery ADU Studio, a design-build practice that has handled garage conversions across Pomona’s central flats, north of Holt, and down toward the Cal Poly Pomona perimeter since 2015. Our crews serve Pomona locally, with dispatch and scheduling coordinated from our Los Angeles office. Call (909) 506-1121 to schedule your free estimate.
Why Ellery ADU Studio Rancho Cucamonga Is Pomona’s Preferred Garage Conversion ADU Company
Pomona homeowners know the difference between a contractor who pulls a permit and a studio that builds the permit set as the core product. We’ve completed garage conversion ADUs on Phillips Blvd, along Mission Blvd, and in the neighborhoods north of the 10 freeway where the 1940s-1960s tract homes sit on some of the largest lots in western LA County. Our clients in Pomona receive a written price before any work starts, per Haven Standard Clause 1, and a documented photo record on every site visit.
Our response time to Pomona is same-week for initial site visits, and we maintain active permit relationships with Pomona Building & Safety that keep our intake packages moving. We don’t guess at what Pomona’s plan checkers want; we know, because we’ve been through their counter with garage conversion ADUs dozens of times.
The 365-Day Done Right Promise backs every project in writing. If the finished ADU is not built to the permitted drawings, we make it right. That’s not a slogan; it’s Haven Standard Clause 7, signed before construction starts.
Our Garage Conversion ADU Services in Pomona
Detached Garage Conversion
Pomona’s central flats were platted with rear service alleys, so a converted detached garage can legally take its own alley-facing address, separate meter location, and tenant entrance. This configuration commands higher rent than a front-facing conversion on the same lot, but it requires early coordination with Pomona Building & Safety and the water/power departments on addressing and service separation during permit intake. We handle that coordination as part of our single-contract design-build process.
We converted a 1948 detached two-car garage on a 9,200 sq ft lot off the alley behind Phillips Blvd, where the alley-side address made the unit rent as a true standalone. The slab-on-grade had zero insulation and the subpanel was a 60-amp fuse box, so we pulled a new 100-amp service, laid a vapor barrier and rigid foam under the new subfloor, and spec’d stainless fasteners and a mini-split sized for the un-shaded stucco heat load. We also sealed every flashing penetration with butyl tape and marine-grade caulk because the summer thermal swing was popping cheap galvanized roofing nails on the original garage roof.
Garage JADU
A Junior ADU conversion inside an existing attached garage is often the fastest path to rental income in Pomona, particularly for homeowners who want to stay on-site while generating cash flow. Pomona’s JADU rules require owner occupancy of either the primary residence or the JADU, and the unit must share utility systems with the main house. We design these conversions to meet the 500-square-foot maximum while preserving functional garage storage or parking where the ordinance allows. Every JADU we quote includes the full permit set and a written price before work starts.
Garage Partition & Bathroom Add
Some Pomona garages are deep enough to split into a studio ADU plus retained parking, or to add a full bathroom where none existed. These partitions trigger Pomona’s full ADU standards, including separate utility metering if the unit is detached, which means early decisions about electrical service size and sewer lateral capacity. We model those constraints in the design phase, not during construction, so the written price we give you accounts for the actual work.
Attached Garage Conversion
Attached garage conversions in Pomona’s post-WWII tract homes often face a critical constraint: the existing 60-amp garage subpanel and uninsulated slab-on-grade floor. Both must be remediated to meet Title 24 habitable-space standards before the conversion permit can close. We address these in the permit set, not as change orders, so the price you sign is the price you pay.
Carport Conversion
Carport conversions in Pomona require full enclosure, foundation evaluation, and often new electrical service where the original carport had none. The city’s hot inland climate means any enclosed carport needs HVAC sized for 105°F+ peak loads, which we specify as a baseline requirement, not an upgrade.
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 Coordinate in Pomona
Our design-build practice specifies and coordinates prefab and modular systems from brands including Boxabl, Plant Prefab, and Tuff Shed within the same single contract that covers your drawings, permits, and construction. For Pomona’s climate, we often pair these systems with James Hardie fiber-cement siding, which handles the thermal swing and UV exposure better than vinyl or wood composites in inland valley conditions. Every material spec is documented in the permit set and locked at signing under Haven Standard Clause 5.
Common Garage Conversion ADU Problems We See in Pomona Homes
- Alley-facing conversions with uncoordinated service separation. Homeowners who skip early coordination with Pomona’s water and power departments end up with a code-violating shared meter and a stalled final inspection. We handle utility separation in the permit intake phase, not after framing is complete.
- Original 60-amp garage subpanels and uninsulated slabs carried into habitable space. These fail Title 24 and force a mid-build electrical and envelope retrofit that adds weeks and thousands to the project. Our permit sets identify these conditions before we break ground.
- Cheap galvanized roofing fasteners and non-sealed flashing failing under thermal cycling. Pomona’s 105°F+ summer temperatures pop standard hardware and open leaks into new conditioned ceilings. We spec stainless or hot-dip galvanized fasteners with marine-grade sealants at every penetration.
- Undersized HVAC specified as an “upgrade” rather than a code baseline. Pomona’s inland valley location means mini-splits must be sized for genuine heat load, including radiant gain from un-shaded concrete and stucco. We size equipment for actual conditions, not coastal assumptions.
Pricing for Garage Conversion ADU in Pomona, CA
Garage conversion ADUs in Pomona typically run $95,000-$165,000 all-in, drawings through final inspection. Detached garage conversions with alley addressing and full utility separation land at the higher end of that range. Attached garage conversions and JADUs with shared systems run lower, assuming the existing slab and electrical can be brought to code without full replacement.
| Component | Typical Range in Pomona |
|---|---|
| Design & permit set | $8,500-$14,000 |
| Foundation/slab remediation | $4,000-$12,000 |
| Electrical service upgrade (100-amp) | $3,500-$7,500 |
| HVAC (mini-split, code-required) | $4,500-$8,500 |
| Insulation & envelope (Title 24) | $6,000-$11,000 |
| Finish construction | $45,000-$85,000 |
| Utility separation & meters | $2,500-$6,000 |
Three factors push Pomona conversions toward the top of these ranges: the mandatory HVAC sizing for 105°F+ peak loads, the electrical and slab remediation common in 1940s-1960s housing stock, and the coordination required for alley-addressed units with separate meters. Every project is quoted with a written price before any work begins, per Haven Standard Clause 1. Call (909) 506-1121 for your exact scope.
We Also Serve Cities Near Pomona
Our crews work throughout the eastern San Gabriel Valley, including Garage Conversion ADU in Pomona and neighboring Montclair, Claremont, La Verne, and San Dimas. Each city has distinct zoning, utility coordination requirements, and housing stock conditions, and our permit sets are prepared accordingly. If you’re comparing estimates across these cities, our Free Second Opinion applies to any written estimate already in hand.
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
Yes, if your lot backs onto one of Pomona’s established rear service alleys. The alley-facing address requires early coordination with Pomona Building & Safety and the water/power departments on service separation and meter location, which we handle during permit intake. Call (909) 506-1121 to check your alley’s eligibility during your free estimate.
Pomona’s 105°F+ summer peak loads make HVAC a code-required baseline, not an optional upgrade, and the inland thermal cycling demands stainless or hot-dip fasteners and marine-grade sealants that coastal projects can skip. Combined with the electrical and slab remediation common in Pomona’s 1940s-1960s housing stock, these factors add $8,000-$18,000 compared to a comparable conversion in a cooler coastal zone. Call (909) 506-1121 for a written price on your specific property.
Three conditions must be resolved: the electrical service must meet current habitable-space standards (typically upgrading from 60-amp fuse boxes), the slab must include proper vapor barrier and insulation, and the envelope must pass Title 24 energy compliance including correctly sized HVAC. Our permit sets identify these items before construction starts so they are included in the written price, not discovered as change orders. Call (909) 506-1121 to schedule a site evaluation.
The alley itself doesn’t change the materials, but the alley-addressed configuration often means the unit’s roof and walls face more direct sun exposure with less shade from the primary residence. We spec stainless or hot-dip galvanized roofing fasteners, marine-grade flashing sealants, and James Hardie fiber-cement siding to handle that thermal load and UV exposure. These specifications are documented in the permit set and locked at signing under Haven Standard Clause 5.
The rental pressure from Cal Poly Pomona’s 27,000+ students makes Pomona’s garage conversion ROI among the strongest in LA County, particularly for alley-addressed units that rent as true standalones. A typical 400-square-foot detached garage ADU in Pomona rents for $1,600-$2,200 monthly, with alley-addressed units at the higher end. Call (909) 506-1121 for a written price and rent comp analysis specific to your neighborhood.
Ready to convert your Pomona garage into income-producing space? Call (909) 506-1121 to schedule your free estimate. You’ll receive a written price before any work starts, a documented photo record on every visit, and the 365-Day Done Right Promise in writing.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Pomona since 2015.