Trusted Garage Conversion ADU for Pomona Homeowners
A garage conversion ADU in Pomona typically runs $85,000-$165,000 all-in, from measured drawings through final inspection, depending on whether your garage is attached, detached, or a carport requiring foundation work. Most Pomona homeowners complete the full process in 6-10 months, with permits moving through the city’s Planning and Community Development Department in 8-14 weeks under current staffing levels. Call (657) 286-7915 - a live person answers, and we’ll review your garage on a free site visit with a written price to follow.
Since 2015, Ellery ADU Studio has designed, permitted, and built over 900 ADUs across Los Angeles and San Bernardino counties, including dozens of garage conversions in Pomona’s specific zoning context. We operate under one contract covering design, permitting, and construction - no designer blaming the builder, no builder claiming the drawings were wrong. Every project starts with a written price per Haven Standard Clause 1, and every site visit produces a documented photo record you receive directly. Nadia Ellery leads the studio, and our license number appears on every page.
Pomona’s housing stock presents particular conditions we see repeatedly: pre-1970s attached garages with uninsulated CMU walls, detached structures on sloped lots in the Phillips Ranch or Lincoln Park areas, and carports originally built without footings that need full foundation retrofits to meet CBC Chapter 18. We price for these conditions specifically, not generically.
What Our Garage Conversion ADU Service Includes
Attached Garage Conversion
An attached garage conversion reuses your existing structure that shares a wall with your primary residence, typically the fastest path to a permitted ADU in Pomona because the utility tie-ins are shorter and the fire separation requirements are simpler to document. You’ll need this when your garage is structurally sound but uninsulated, unpermitted as living space, or when you want to add a kitchenette and full bath for rental income or family use. At Ellery ADU Studio Pomona, we start with a structural assessment of the existing slab - many Pomona garages in the Mayfair or Westmont neighborhoods have 3.5-inch slabs that require a supplementary foundation design to carry residential loads - and we include that engineering in your permit set from day one, not as a change order after demo.
Detached Garage Conversion
A detached garage conversion transforms a standalone structure into independent living space, which in Pomona triggers specific setback and utility separation rules under the municipal code. You need this when your property has a rear or side garage that can become a rental unit, in-law quarters, or home office with its own entrance. We handle the full utility extension - sewer lateral, water service, and electrical subpanel - and we coordinate with Southern California Edison and Golden State Water on your behalf. Our permit set includes the site plan showing exact distances to property lines, which Pomona’s planners verify against their GIS parcel data before issuing the building permit.
Carport Conversion
A carport conversion is the most involved garage conversion type because carports lack three walls and a proper foundation, requiring new construction integrated with the retained roof structure. You need this when you have covered parking you want to enclose, or when your property’s zoning won’t allow a new detached ADU but will permit conversion of existing covered area. We see this frequently in Pomona’s older neighborhoods near downtown, where 1950s carports on minimal footings need complete foundation replacement. Our process includes soils testing where the existing slab is absent, and we specify either a conventional spread footing or a post-tensioned slab depending on your lot’s geotechnical report - all priced in writing before we pull the first permit.
Garage Partition & Bathroom Add
A garage partition and bathroom add splits your existing garage into a partial ADU while retaining vehicle storage, or adds a bathroom to an already-converted space that lacks full plumbing. You need this when you want rental income without losing all parking, or when a previous unpermitted conversion needs to be brought to code with proper sanitation. We document the existing square footage against Pomona’s ADU size limits - 850 square feet for a studio or one-bedroom, 1,000 square feet for two bedrooms - and we design the partition as a one-hour fire-rated assembly per CBC Table 602.3. The bathroom rough-in includes venting through the roof or a side wall, not an illegal dry vent, and we show this in the plumbing isometric on every permit set.
Garage JADU
A garage JADU, or Junior ADU, is a conversion of 500 square feet or less within your existing garage, created without requiring additional parking replacement under California Government Code Section 65852.22. You need this when you want the simplest, lowest-cost legal unit possible, or when your lot size or utility capacity won’t support a full ADU. We design these with efficiency kitchens - 30-inch cooktops, compact refrigerators, and single-bowl sinks - and we verify that your existing electrical panel can handle the 40-amp minimum load without service upgrade. In Pomona’s Arroyo Vista and Orange Grove areas, we’ve completed JADUs that rent for $1,200-$1,500 monthly, with permit sets that move through the city in 6-8 weeks because the code requirements are streamlined.
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.
Brands We Service for Garage Conversion ADU
We specify and coordinate prefab and modular systems from Plant Prefab and Tuff Shed when a garage conversion benefits from factory-built wall panels or roof trusses that integrate with retained structure. With Plant Prefab, we’ve used their LivingHome panels to enclose carport conversions with high-performance envelopes - R-23 walls, R-38 roofs - that exceed Title 24 requirements and reduce your HERS verification costs. Tuff Shed’s engineered wood buildings serve as the structural core for detached garage replacements in Pomona’s hillside zones, where their prescriptive foundation designs save weeks of custom engineering. We also specify James Hardie fiber-cement siding on nearly every conversion we touch, both for its 50-year warranty and for its ignition-resistant rating that satisfies Pomona’s wildland-urban interface requirements in the northern foothill areas.
Whether your project involves these brands or conventional stick-frame construction, we source materials through our single-contract model - no separate procurement phase, no owner-supplied items that void our warranty. Our crews are background-checked and uniformed, and every installation is photographed at rough-in, insulation, and final walkthrough for your documented record.
Signs You Need Garage Conversion ADU Right Now
- Your garage is currently unpermitted living space. Pomona’s code enforcement has increased inspections in response to state housing mandates, and unpermitted conversions face red-tag risk. We can legalize existing work where structurally feasible, or design a full replacement that carries a certificate of occupancy.
- Your mortgage payment has risen significantly since purchase. Homeowners who bought in Pomona between 2015 and 2022 are seeing adjustable-rate resets or refi costs that strain monthly budgets. A permitted ADU generates $1,500-$2,800 in monthly rental income, depending on bedroom count and neighborhood, turning a cost center into an asset.
- Your garage slab is cracking or heaving. Differential settlement in Pomona’s clay soils, particularly in the Ganesha Hills area, indicates the foundation won’t carry residential loads without intervention. We assess this on our first site visit and price the repair in your written quote, not as a surprise after demolition.
- You need housing for family members but lack capital for a detached ADU. A garage conversion uses existing structure and often qualifies for lower-impact fees under Pomona’s ADU ordinance. The total project cost runs 40-60% less than new construction, with faster permit timelines.
- Your property’s zoning changed under recent state law. SB 9 and subsequent legislation may have removed minimum lot size or setback barriers that previously blocked your conversion. We verify your current entitlements against Pomona’s latest general plan and can tell you in 48 hours whether your project is now feasible.
Our Garage Conversion ADU Process - Step by Step
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Site Measure and Feasibility Review. We visit your Pomona property with a laser measure, moisture meter, and slab probe to document existing conditions. You receive a photo record of what we found - foundation depth, wall construction type, electrical panel capacity, sewer lateral location - and a written feasibility memo within three business days. This visit is free, and you owe nothing if the project doesn’t pencil.
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Design and Permit Set Development. Our architects produce construction drawings including floor plans, elevations, structural calculations, MEP isometrics, and energy compliance documentation (Title 24, CF-1R). For Pomona submittal, we include the ADU application checklist, neighbor notification letters where required, and the School Facility Fee calculation. The permit set is the core product - everything that follows is built from these documents.
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Pricing and Contracting. We deliver a written, line-item price before any work begins, per Haven Standard Clause 1. The scope is locked at signing under Clause 5 (No Surprises). No allowances that balloon, no “TBD” line items. You know the exact cost of foundation work, framing, insulation, finishes, and permit fees before we pull the first permit.
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Permit Pull and Construction. We submit to Pomona’s Planning Division and Building & Safety simultaneously where possible, tracking the plan check through the city’s Accela portal. Construction proceeds in phases - demolition, foundation or slab repair, framing, MEP rough-in, insulation, drywall, finishes - with a documented photo record at each phase. Our project manager coordinates inspections; you don’t call the city.
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Final Inspection and Warranty Activation. We pass final inspection, obtain your certificate of occupancy, and deliver the complete as-built drawing set plus warranty documentation. The 365-Day Done Right Promise activates on that date: if any element is not built to the permitted drawings, we make it right, in writing, with no deductible or service fee.
How Much Does Garage Conversion ADU Cost in Pomona?
A typical attached garage conversion in Pomona runs $85,000-$125,000 all-in, from measured drawings through final inspection, as detailed in our garage conversion ADU cost guide. Detached garage conversions range $110,000-$165,000 depending on utility extension length and whether the existing foundation requires replacement. Carport conversions, which need full foundation and wall construction, typically fall at the higher end of that range or slightly above. JADUs and garage partition projects start around $65,000-$85,000 when the existing structure is sound and utility tie-ins are short.
Several factors move these numbers. Foundation condition is the largest variable - a 4-inch slab with rebar in good shape needs no structural work, while a cracked, unreinforced 3-inch slab in the Ganesha Hills clay zone can add $15,000-$30,000 for underpinning or replacement. Utility distance matters: extending sewer 40 feet to a rear detached garage is straightforward; running 120 feet under existing hardscape to a side carport adds excavation and restoration costs. Finish level affects the final 20% of budget - vinyl plank and quartz counters versus tile and granite - but we specify these choices in writing before construction, not as showroom upsells.
Permit fees in Pomona currently run $3,500-$7,500 for garage conversions depending on valuation, plus school facility fees where applicable. We itemize these in your written quote, not as a lump-sum “permits and fees” mystery box. Impact fees for ADUs are capped or waived under state law for most projects.
To avoid overpaying, get a second opinion on any estimate already in hand - we offer this free, with no obligation to hire us. Compare line-item detail: a quote with one number and a long exclusions list will grow. Ours specifies every phase, every material spec, every permit fee. Under Haven Standard Clause 1, the price you sign is the price you pay.
Garage Conversion ADU Near Pomona - Our Service Area
We design, permit, and build garage conversion ADUs throughout Pomona and neighboring cities including Garage Conversion ADU in Montclair, Garage Conversion ADU in San Dimas, Diamond Bar, Upland, Covina, Glendora, Chino, Chino Hills, West Covina, Ontario, and Rowland Heights. Typical response time for a site visit is 2-4 business days in Pomona proper, 3-5 days for outlying areas. We know the specific planners and inspectors in each jurisdiction - Pomona’s requirements differ from Montclair’s, which differ from San Dimas’s - and we tailor every permit set accordingly. Whether you’re near Cal Poly Pomona, in the historic Lincoln Park district, or up in Phillips Ranch, we measure, price, and build to your specific conditions.
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.
Frequently Asked Questions - Garage Conversion ADU in Pomona
A garage conversion ADU transforms an existing garage or carport into a legally permitted accessory dwelling unit with its own kitchen, bathroom, and living space. In Pomona, this is governed by the municipal ADU ordinance, California Government Code Sections 65852.2 and 65852.22, and the California Building Code. Ellery ADU Studio handles the full process - measured drawings, structural engineering, permit submittal, construction, and final inspection - under one contract at one written price. Call (657) 286-7915 to schedule a free feasibility review.
Most garage conversion ADUs in Pomona take 6-10 months from contract signing to certificate of occupancy, with permit processing accounting for 8-14 weeks of that timeline. Attached garage conversions on sound foundations move fastest; carport conversions requiring new foundations and detached structures needing long utility runs take longer. We track your permit through the city’s Accela system and coordinate inspections so you don’t wait on callbacks. Call (657) 286-7915 for a timeline estimate specific to your property.
Attached garage conversions in Pomona typically cost $85,000-$125,000 all-in; detached conversions run $110,000-$165,000; JADUs and partition projects start at $65,000-$85,000. Carport conversions, which need full foundation work, fall at the higher end. Every project receives a written, line-item price before work begins per Haven Standard Clause 1 - no estimates that balloon, no hidden fees. Call (657) 286-7915 for your specific written quote; the site visit is free.
Yes - we specify and coordinate prefab and modular systems from Plant Prefab, Tuff Shed, and other manufacturers when your project benefits from factory-built components. For garage conversions, we most often use prefab wall panels or roof trusses that integrate with retained structure, not full module delivery, because the existing garage defines the footprint. We handle all coordination - engineering compatibility, crane scheduling if needed, and utility connections - within our single contract. Call (657) 286-7915 to discuss whether prefab makes sense for your conversion.
No - garage conversion ADUs are planned construction projects, not emergency repairs. We do not promise same-day dispatch or 24-hour construction starts. What we do promise is a live person answering your call 24/7 to schedule your free site visit, typically within 2-4 business days in Pomona. Once contracted, we maintain consistent crew presence and communicate weekly progress. Call (657) 286-7915 to start the planning process.
Every garage conversion ADU carries our 365-Day Done Right Promise: if the finished unit is not built to the permitted drawings, we make it right, in writing, with no deductible or service fee. This is backed by Haven Standard Clause 8, which you receive before signing. We also pass through all manufacturer warranties on materials - James Hardie siding, plumbing fixtures, electrical panels - and we document installation compliance so those warranties remain valid. Call (657) 286-7915 for a copy of the full warranty terms.
Gather any existing property surveys, previous permit records, or HOA correspondence; locate your electrical panel and main water shutoff; and note any known conditions like slab cracks, roof leaks, or previous unpermitted work. We handle the technical assessment - slab depth, structural capacity, utility routing - on site. You don’t need to clear the garage completely, but access to all walls and the slab surface helps us measure accurately. Call (657) 286-7915 to schedule; the visit is free and you receive a written price within three business days.
Schedule Your Garage Conversion ADU Service in Pomona Today
Call (657) 286-7915 to schedule your free site visit and written estimate. A live person answers 24/7. We’ll measure your garage, assess foundation and utility conditions, and deliver a line-item price within three business days - no obligation, no “call for pricing,” no surprises later. Every project is governed by The Haven Standard: written price before work starts, documented photo record on every visit, and our 365-Day Done Right Promise backed in writing. Nadia Ellery and the team at Ellery ADU Studio Pomona have designed, permitted, and built over 900 ADUs since 2015, and we’re ready to add yours to that number.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving Pomona since 2015.