Trusted Garage Conversion ADU for San Bernardino Homeowners
A garage conversion ADU in San Bernardino typically runs $95,000-$175,000 all-in, from measured drawings through final inspection, depending on whether your garage is attached, detached, or currently a carport. Most San Bernardino homeowners complete the full design-build process in 6-10 months, with permit approval through the city taking 8-14 weeks once the set is filed. Ellery ADU Studio has designed, permitted, and built 900+ ADUs since 2015, the year California’s state laws shifted to mandate ministerial approval for qualifying projects. Call (909) 359-6463 to schedule your free estimate with a written price before any work starts.
San Bernardino’s housing stock includes thousands of post-war garages in neighborhoods like Del Rosa, Arrowhead, and the North Park area. Many were built on 4-inch slabs with no foundation separation from the main house, which affects how we approach the structural analysis. The city’s inland climate, with summer highs above 100°F and winter lows near freezing, means insulation and HVAC sizing decisions matter for long-term utility costs. We’ve worked with San Bernardino’s Planning and Building & Safety divisions long enough to know which inspectors flag fire-separation details and which want to see the energy compliance path before they pick up the file.
Our home page outlines the full Ellery ADU Studio scope. This page covers garage conversion ADUs specifically, including attached and detached structures, carport enclosures, partitioned garage JADUs, and bathroom additions within existing garage footprints.
What Our Garage Conversion ADU Service Includes
Attached Garage Conversion
An attached garage conversion turns the structure sharing a wall with your main house into a self-contained dwelling unit with its own kitchen, bathroom, sleeping area, and separate entrance. In San Bernardino, these conversions require fire-rated separation between the ADU and the primary residence, typically one-hour Type X gypsum on the shared wall and a self-closing fire door. We see this most often in Del Rosa and Arrowhead, where 1950s-1970s ranches have two-car garages directly off the kitchen. Ellery ADU Studio produces the full permit set, including the fire-separation detail, the Title 24 energy compliance package, and the electrical load calculation showing the panel can handle the additional demand. Under Haven Standard Clause 1, you receive a written price covering drawings, permits, and construction before any work begins.
Detached Garage Conversion
A detached garage conversion transforms a standalone structure into a complete dwelling unit, often with more design flexibility than attached conversions because fire separation is achieved through distance rather than wall assembly. San Bernardino’s older neighborhoods, particularly around the downtown core and along Base Line, have many detached garages on alley-accessed lots where parking replacement can be satisfied with a new surface space rather than covered replacement. The existing slab often needs reinforcement or replacement, since original garage slabs were poured at 3.5-4 inches without footings or rebar. We test for this during our initial site visit, document the findings with photos you receive, and specify exactly what the foundation line item covers. Our 365-Day Done Right Promise applies to the finished unit matching the permitted drawings.
Carport Conversion
A carport conversion encloses an open-sided structure to create a conditioned ADU, which typically requires more structural intervention than a garage conversion because carports lack three existing walls and a sealed roof assembly. In San Bernardino’s wind-prone areas, particularly near the Cajon Pass corridor in northern neighborhoods, the new wall assembly must meet the city’s wind-load requirements, which often means engineered shear walls rather than conventional framing. We specify the exact wall system in the permit set, coordinate the structural engineering peer review, and include the full enclosure in our single-contract price. The Haven Standard Clause 5 (No Surprises) locks this scope at signing; no door-side upsells when the framer discovers the carport posts are rotted.
Garage Partition & Bathroom Add
A garage partition and bathroom add creates a Junior ADU or partial conversion within an existing garage footprint, typically retaining vehicle storage on one side while adding a studio or one-bedroom unit on the other. This works well in San Bernardino’s smaller lots where replacement parking is tight, particularly in the flood-adjacent neighborhoods near the Santa Ana River where setback requirements limit expansion. The bathroom addition requires tying into existing sewer lines, often with a sewage ejector pump if the garage slab sits below the main line invert. We map this during our video pipe inspection, show you the footage, and specify the exact pumping system in the permit set. Every project includes a documented photo record on every visit.
Garage JADU
A garage JADU, or Junior ADU, is a compact unit of up to 500 square feet created within an existing garage, with an efficiency kitchen and either a separate bathroom or shared bathroom access. San Bernardino’s JADU path moves faster through permitting than full ADUs in many cases, and owner-occupancy of either the main house or the JADU is required. We see strong demand for these in the University District and near CSUSB, where homeowners want rental income without the full construction scope of a detached ADU. Ellery ADU Studio handles the JADU-specific code analysis, including the reduced parking replacement requirement and the owner-occupancy affidavit, within the same single contract. The written price covers everything from the measured drawings to the final certificate of occupancy.
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
Ellery ADU Studio specifies and coordinates prefab and modular systems from leading manufacturers, integrating them into garage conversion ADU projects where the existing structure requires replacement rather than retrofit. We’ve worked with Abodu units extensively, particularly their one-bedroom models that fit well on San Bernardino’s standard 5,000-square-foot lots; we handle the site prep, utility tie-ins, and final connection to city sewer and water under our single contract. Cover systems, with their steel-frame precision and rapid on-site assembly, work well for homeowners who need to replace a deteriorated detached garage with a high-performance unit; we coordinate their factory scheduling with our permit timeline so neither waits on the other. Dvele and Mighty Buildings offer alternative approaches, Dvele with its integrated smart-home systems and Mighty Buildings with its 3D-printed polymer composite panels that reduce on-site labor.
Whether your project involves Abodu, Cover, Dvele, Mighty Buildings, or any other manufactured system, we specify the exact brand, model, and options in the permit set and lock the price in writing before work starts. Our fluency across these platforms means we can compare true all-in costs, including the foundation, utility runs, and finish work that factory quotes often exclude. Call (909) 359-6463 for a Free Second Opinion on any written estimate already in hand.
Signs You Need Garage Conversion ADU Right Now
- Your garage slab is cracking or settling unevenly. Differential settlement means the original 4-inch slab without footings is failing under its own load, let alone the added weight of walls, insulation, and finishes. In San Bernardino’s expansive clay soils, particularly in the foothill neighborhoods near Highland and Redlands, this worsens with seasonal moisture cycles. We assess the slab with a laser level and specify exactly what foundation work the permit set includes.
- The garage has no insulation or existing HVAC connection. Converting a raw garage to habitable space in San Bernardino’s climate zone requires R-13 minimum wall insulation and R-30 ceiling insulation, plus mechanical heating and cooling sized to the new conditioned volume. If you’re already considering the conversion, delaying means another summer of 100°F-plus heat radiating through uninsulated walls into whatever you’re storing there.
- Your household needs rental income or multigenerational space. San Bernardino’s median rent for a one-bedroom unit exceeds $1,600 monthly, and a garage ADU typically rents for $1,200-$1,800 depending on finish level and neighborhood. The cost of waiting is measurable monthly income you don’t collect, plus construction cost inflation that has averaged 4-7% annually in the Inland Empire.
- The existing garage door is failing or non-functional. A garage door replacement on a structure you plan to convert is wasted money; the opening will be framed and sealed as part of the ADU enclosure. If you’re facing a $2,500-$4,000 door replacement decision now, that money belongs in the conversion budget instead.
- San Bernardino’s ADU ordinance is favorable now, but local politics shift. The city currently permits garage conversions ministerially under state law, with no discretionary review for qualifying projects. Council discussions about infrastructure impact fees and parking requirements recur periodically. The permit set you file locks in the rules at filing date, not at completion.
Our Garage Conversion ADU Process - Step by Step
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Site Measure and Feasibility Review. We visit your San Bernardino property with a laser measure, moisture meter, and camera. We document the existing slab thickness, roof structure, electrical panel capacity, and sewer line depth. You receive the photo record within 24 hours, with each image annotated for what it means for your project.
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Design and Permit Set Production. Our in-house designer produces the full construction document set: floor plans, elevations, sections, structural calculations, Title 24 energy compliance, and San Bernardino-specific forms. The permit set is the core product, not an afterthought; we revise until it reflects exactly what will be built.
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Written Price and Contract. Under Haven Standard Clause 1, you receive a line-item written price covering design, permitting, and construction before any work begins. The scope is locked under Clause 5 (No Surprises). You know the foundation line item, the electrical upgrade line item, the finish package line item, and the total.
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Permit Filing and City Coordination. We file directly with San Bernardino Building & Safety and respond to corrections without passing the burden to you. Typical turnaround is 8-14 weeks for a complete garage conversion ADU, faster for JADU projects. We track the file daily and update you at each status change.
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Construction and Final Inspection. Our background-checked, uniformed crews build to the permitted drawings. A documented photo record accompanies every site visit. After final inspection and certificate of occupancy, the 365-Day Done Right Promise takes effect: if the finished ADU doesn’t match the permitted drawings, we make it right in writing.
How Much Does Garage Conversion ADU Cost in San Bernardino?
A typical attached garage conversion ADU in San Bernardino runs $95,000-$140,000 all-in, from measured drawings through final inspection, per our garage conversion ADU cost guide. Detached garage conversions, which often require more extensive foundation and utility work, typically range $110,000-$175,000. Carport conversions fall between these figures depending on how much structure needs to be built from scratch. Garage JADUs, with their smaller footprint and reduced finish requirements, generally run $75,000-$115,000. These ranges assume a standard 400-600 square foot unit with mid-grade finishes; high-end finishes, significant foundation replacement, or complex utility routing push toward the upper end.
| Project Type | Typical Range (San Bernardino) | Key Cost Driver |
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| Attached Garage Conversion ADU | $95,000 - $140,000 | Fire separation, electrical panel upgrade |
| Detached Garage Conversion ADU | $110,000 - $175,000 | Foundation replacement, utility trenching |
| Carport Conversion ADU | $100,000 - $155,000 | Wall and roof assembly from scratch |
| Garage Partition & Bathroom Add | $85,000 - $125,000 | Sewage ejector, wet wall location |
| Garage JADU (under 500 sq ft) | $75,000 - $115,000 | Efficiency kitchen, shared vs. separate bath |
What moves the price within these ranges? Foundation condition is the biggest variable. A 4-inch slab with no cracks and adequate soil bearing keeps the foundation line item modest; a settled slab requiring full replacement with footings and rebar adds $15,000-$35,000. Electrical panel capacity matters too: a 100-amp service often needs upgrade to 200 amps for an ADU, particularly if the main house has electric heat or EV charging. San Bernardino’s sewer connection fees, currently among the lower rates in the Inland Empire, add predictability on the utility side.
How to avoid overpaying? Get the full permit set before you get construction bids. Contractors bidding from a napkin sketch pad contingencies; a complete drawing set lets them price accurately and competitively. Our Free Second Opinion service reviews any written estimate you’ve already received, line by line, against the permit set to identify scope gaps or inflated contingencies.
What’s included in our free estimate? We visit your property, measure and photograph, and return a written feasibility assessment with a preliminary budget range. If you proceed, the full permit set and fixed written price follow. Call (909) 359-6463 to schedule.
Garage Conversion ADU Near San Bernardino - Our Service Area
Ellery ADU Studio serves San Bernardino and the surrounding Inland Empire cities, including Rialto, Colton, Grand Terrace, Highland, Redlands, Fontana, Riverside, Rancho Cucamonga, Moreno Valley, Yucaipa, and Hesperia. Typical initial site visits are scheduled within 3-5 business days of contact, with permit filing following immediately upon design approval. We’ve filed permit sets in each of these jurisdictions and understand their specific correction cycles, from Riverside’s enhanced fire-separation review to Fontana’s utility coordination requirements. For homeowners in the Cajon Pass corridor or Yucaipa’s bench areas, we account for snow load and wind exposure in the structural specification.
Serving San Bernardino, CA - Our Local Coverage Area
We’re based in the San Bernardino 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 San Bernardino
A garage conversion ADU transforms an existing garage structure into a legally permitted accessory dwelling unit with its own kitchen, bathroom, sleeping area, and separate entrance. In San Bernardino, this path is typically faster and less expensive than building a new detached ADU because you’re working within an existing footprint and may avoid certain impact fees. The converted unit must meet all California Building Code requirements for habitability, including ceiling height, natural light, ventilation, and energy efficiency. Call (909) 359-6463 for a free feasibility assessment of your specific garage.
Most garage conversion ADUs in San Bernardino take 6-10 months from initial site visit to certificate of occupancy, with 8-14 weeks of that in city permit review. JADU projects move faster, typically 4-7 months total. Delays usually stem from incomplete permit sets or unresolved property line disputes, which is why we produce the full construction document set before filing and verify setbacks with a surveyor when boundaries are unclear. Our documented photo record keeps you informed at every phase so you know exactly where the project stands.
Garage conversion ADUs in San Bernardino typically range $75,000-$175,000 all-in depending on attached versus detached configuration, foundation condition, and finish level. A written line-item price covering drawings, permits, and construction is provided before any work starts under Haven Standard Clause 1. No call-for-quote games, no open-ended allowances. Call (909) 359-6463 for your specific written estimate.
Yes. We specify and coordinate Abodu, Cover, Dvele, Mighty Buildings, and other prefab systems within our single-contract design-build model, handling site prep, utility connections, and final finish work that factory quotes typically exclude. The prefab unit, foundation, and connection work are all covered under one written price with one point of accountability. If you’re comparing a prefab garage replacement to a site-built conversion, we can model both scenarios with true all-in costs.
Most San Bernardino homeowners remain in their primary residence during garage conversion ADU construction, as the work is separated from the main living space and typically doesn’t require utility shutoffs to the house. For attached garage conversions, we sequence the fire-separation work to maintain your home’s safety and habitability throughout. Dust and noise are localized to the construction zone; we specify protection measures in the pre-construction walkthrough and document compliance in the photo record. Call (909) 359-6463 to discuss your specific living situation.
Every garage conversion ADU is backed by our 365-Day Done Right Promise: if the finished unit is not built to the permitted drawings, we make it right, in writing, before the project starts. This is Haven Standard Clause 7, not a verbal assurance. Beyond our promise, standard manufacturer warranties apply to fixtures, appliances, and specified equipment. The permit set itself, which governs what must be built, is your long-term protection against substandard work.
Clear access to the garage and any side yards where utility connections run is helpful; beyond that, no preparation is required. We bring all measurement and documentation tools. If you have a recent survey, property plat, or previous permit drawings, those accelerate our initial assessment but aren’t necessary. We’ll ask about your intended use, rental income expectations, and any must-have features to inform the preliminary budget range. Call (909) 359-6463 to schedule your free estimate with a written price before any work starts.
Schedule Your Garage Conversion ADU Service in San Bernardino Today
Call (909) 359-6463 to schedule your free estimate. A live person answers 24/7, no voicemail queue. 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. If you already have a written estimate from another firm, ask for our Free Second Opinion. Ellery ADU Studio has operated as a design-build studio since 2015, with 900+ ADUs designed, permitted, and built under one contract at one written price.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving San Bernardino since 2015.