Fast, Reliable Garage Conversion ADU Across San Dimas
Garage conversion ADUs in San Dimas typically run $165,000 to $280,000 all-in, from as-built drawings through final inspection, with detached garage conversions on larger foothill or equestrian parcels landing at the higher end. We coordinate permits through both San Dimas city planning and Los Angeles County where parcel boundaries split jurisdiction, which happens more often here than homeowners expect. If you’re weighing a garage conversion on a half-acre lot off Lone Hill Avenue or a detached structure behind a 1960s ranch near San Dimas Canyon Road, call (971) 497-2402 and we’ll give you a written price before any work starts.
Why Ellery ADU Studio Is San Dimas’s Preferred Garage Conversion ADU Company
We’re a design-build studio, not a contractor juggling a designer and a builder who point fingers when a change order appears. Since 2015, we’ve designed, permitted, and built over 900 ADUs across Southern California, every one with a written price before work began and a documented photo record when the job was done. Our Garage Conversion ADU team handles the drawings, the permit set, and the construction under one contract, which means a single fixed price covers the whole thing.
San Dimas work has a specific rhythm. Equestrian-zoned parcels need county permit research before we touch a stable or tack room conversion. Foothill lots require slope analysis and sometimes retaining walls before a slab goes down. We’ve done enough of these to know which questions to ask first. A live person answers our phone 24/7, and that person can schedule your estimate for a garage conversion in San Dimas the same week you call.
Nadia Ellery founded this studio on a simple rule: the permit set is the product, not an afterthought. That’s why every San Dimas garage conversion gets a full drawing package, a written scope locked at signing, and The Haven Standard in writing, including our 365-Day Done Right Promise. If the finished ADU is not built to the permitted drawings, we make it right.
Our Garage Conversion ADU Services in San Dimas
Detached Garage Conversion
Detached garage conversions are the most common project we scope in San Dimas, largely because the city’s stock of 1960s and 1970s ranch homes came with generous detached garages set back from the main house. A two-car detached garage off a street like San Dimas Avenue or Cienega Avenue often converts cleanly into a 400 to 500 square foot one-bedroom ADU. On equestrian-zoned properties where the garage sits far from the street, we price the longer material hauls, equipment access, and any trenching for utilities separately and show you those line items before you sign anything, per Haven Standard Clause 1.
Attached Garage Conversion
Attached garage conversions in San Dimas usually involve a split-level ranch or a California bungalow near the historic downtown along Bonita Avenue. Fire separation between the ADU and the main house is required, which means the shared wall needs specific drywall and insulation upgrades. We’ve done enough of these in San Dimas to know what the city’s plan checkers flag: the wall assembly, the existing slab thickness, and whether the garage door opening is being converted to an exterior wall with a proper header. The drawings address all of it before you pay for construction.
Garage Partition & Bathroom Add
This is a San Dimas-specific pattern we see constantly: homeowners want to keep two-thirds of a wide two-car garage for cars and a workshop, then partition off one bay into a studio ADU with a compact three-quarter bath. It works well when the garage is deep enough, which many San Dimas detached garages are. The plumbing is the variable cost driver. If the garage slab sits close to the main sewer line, it’s a straightforward tie-in. If not, we’re pricing a grinder pump or an alternate drainage routing, and that number goes in the written quote before work starts.
Garage JADU
A Junior ADU inside an existing attached garage is the fastest permitted path in San Dimas, capped at 500 square feet and allowed to share some plumbing with the main house. We’ve permitted garage JADUs in San Dimas neighborhoods where the owner wants rental income without adding a second structure to the lot. The city reviews these faster than a detached conversion, and the lower scope keeps the typical price between $80,000 and $120,000, drawings and permits included.
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 San Dimas
We specify and coordinate prefab and modular systems from James Hardie, Abodu, and Cover within our San Dimas garage conversion contracts. When a detached garage on a large foothill lot needs new exterior siding after the conversion, James Hardie fiber cement from our local supplier goes on the elevations without adding a separate vendor to the job. For homeowners who want a faster build, we’ve coordinated Abodu and Cover modules on San Dimas sites where the lot access allowed a crane or flatbed placement. These are not separate contractors you hire. They’re coordinated under the same single contract and written price as the rest of the conversion.
Common Garage Conversion ADU Problems We See in San Dimas Homes
- Unpermitted prior conversions. A garage that was half-finished by a previous owner with no permit creates a stop-work risk when the city discovers the unpermitted work during plan review. We pull the original permit history from San Dimas’ building department before we quote, so the written price reflects reality, not an assumption.
- VHFHSZ fire-zone requirements. Parcels on the northern and eastern edges of San Dimas that press against the San Gabriel foothills fall inside California’s Very High Fire Hazard Severity Zone. That changes the exterior assembly, the venting, and the roof covering on an attached garage conversion, adding $12,000 to $25,000 that flat-valley cities like Covina never see.
- Slope and drainage on foothill lots. A detached garage that looks flat on Google Earth can sit on a lot with a 6 to 10 percent grade once we shoot elevations. If the slab drains toward the garage or a retaining wall is needed before construction, that’s an engineered foundation line item, not a surprise.
- Large-lot access and haul distances. On equestrian parcels with the garage 150 feet or more from the street, material delivery, concrete pumping, and equipment staging cost more in San Dimas than on a standard 6,000 square foot lot in Glendora. We scope that as a site logistics line item and show it to you before you commit.
Pricing for Garage Conversion ADU in San Dimas, CA
Here are the ranges we quote most often in San Dimas:
- Garage JADU: $80,000 - $120,000
- Attached garage conversion (full): $140,000 - $210,000
- Detached garage conversion (full): $165,000 - $260,000
- Garage partition with bathroom add: $95,000 - $150,000
- Barn, stable, or tack room conversion into ADU: $150,000 - $280,000
These are all-in numbers: drawings, permit set, city fees, construction, and final inspection. What moves the price in San Dimas more than any other variable is the parcel itself. A flat lot south of Arrow Highway with a detached garage 20 feet from the street sits at the low end. A foothill parcel requiring fire-rated assemblies, engineered retaining, and a 200-foot utility trench sits at the high end. You’ll see every line item in writing before work starts, and the scope is locked at signing under Haven Standard Clause 5, No Surprises. Call (971) 497-2402 for a free estimate and a written price.
We Also Serve Cities Near San Dimas
Beyond San Dimas, our garage conversion team covers La Verne, Glendora, Covina, and Azusa. The permitting environments differ slightly city by city: Covina sits outside the fire zone, Glendora has its own foothill parcels, and La Verne shares San Dimas’ equestrian zoning heritage. The page you’re on covers San Dimas specifically, but the same written-price rule applies everywhere we work.
Serving San Dimas, CA - Our Local Coverage Area
We’re based in the San Dimas 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 San Dimas
Yes, and in San Dimas this is often cheaper than new construction because the structure already has electrical service and a water line. The catch is documentation: the city will not approve a change-of-use on an accessory structure unless you can prove its legal status through the original permit history. We pull that research before quoting so the written price reflects what the city will actually approve. Call (971) 497-2402 and we’ll walk you through what your specific stable or tack room needs.
If your parcel sits in the northern or eastern foothills of San Dimas, yes. The Very High Fire Hazard Severity Zone triggers Class A roofing, ember-resistant vents, and fire-rated exterior assemblies on any garage conversion. This adds real cost, usually $12,000 to $25,000, and it’s non-negotiable. We scope it during the site walk, not during plan check.
Expect a site logistics line item covering longer material hauls, concrete pumping distance, and equipment access. If the garage is 100 feet or more from the street on a half-acre or larger parcel, that line item typically runs $8,000 to $18,000 depending on grade and access width. Your written estimate lists it separately so you can see exactly where the money goes.
San Dimas approves ADUs on equestrian-zoned parcels, but the review is not the same as a flat residential lot. The planning staff will ask for the accessory structure’s permit history, and if the lot is inside the VHFHSZ, the fire-zone material requirements apply. We’ve permitted garage and barn conversions on equestrian parcels across San Dimas, and the step that saves money every time is pulling the original records before drawings are finalized.
Yes. A partition conversion keeps one bay as a garage or storage area and builds a separate studio ADU in the other bay, with a fire-rated wall between them. The depth of your existing garage determines whether it works: many San Dimas attached garages are deep enough, but some of the older bungalows near Bonita Avenue are not. We’ll measure during the estimate and tell you straight if the numbers work.
For a free estimate and a written price on your San Dimas garage conversion, call (971) 497-2402. We answer the phone when you call.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving San Dimas since 2015.