







A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable Garage Conversion Contractor Across San Gabriel
A garage conversion in San Gabriel typically runs $95,000 to $165,000 for an attached conversion and $120,000 to $210,000 for a detached garage converted to an ADU, before permit fees. That range reflects what we see across San Gabriel’s housing stock: 1940s and 1950s ranches with single-car garages, 1960s tracts off San Gabriel Boulevard, and larger two-car detached garages on 50-foot lots near the Mission District. Fielding ADU Builders serves San Gabriel directly, with crews who know the city’s permit counter, its setback rules, and its older slabs. If you want a written price before any work starts, call (361) 315-4177.
Why Fielding ADU Builders Is San Gabriel’s Preferred Garage Conversion Contractor Company

Homeowners in San Gabriel call us after a previous contractor went quiet or moved the number at the door. We operate differently. Every project starts with a written price – not an estimate range, a fixed line-item number handed to you before a single nail is driven. That price holds. Reed Calloway, who leads Fielding ADU Builders, built the company’s reputation on showing up in the window, pricing in writing, and standing behind the work for a full year under The Garrison Code: show up, price in writing, by the book, leave it clean, stand behind it.
Our crews are background-checked and arrive in uniform, so you always know who is on your property. When you call, a live person answers – noon or midnight, it does not matter. We do not route you to a voicemail queue. For San Gabriel specifically, that matters because plan check questions, permit corrections, and inspection scheduling here require someone who answers the phone and knows the city’s process.
We are part of the Garrison Partners family, which has been building to The Garrison Standard since 2006. Fielding ADU Builders is independently owned and operated, not a franchise. We work with prefab and modular platforms like Cover, Dvele, and Mighty Buildings, and we also build conventional conversions with James Hardie siding. That range lets us match the build method to your San Gabriel lot and budget rather than forcing one approach.
Garage Apartment Conversion in San Gabriel
Garage Apartment Conversion in San Gabriel means turning an existing garage – attached or detached – into a permitted dwelling unit with its own entrance, kitchen, bath, and sleeping area. On San Gabriel’s typical 50-foot-wide residential lots, this is often the most cost-effective way to add a rental unit or a home for an aging parent without sacrificing yard space. A garage apartment conversion here usually runs $130,000 to $210,000 for a detached structure, with the spread driven by whether you need a new slab, a structural ridge beam, and utility upgrades.
Attached Garage to Apartment
An attached garage conversion shares a wall and roofline with the main house. That lowers foundation costs because the existing footings often work, but it raises fire separation requirements – you will need a one-hour rated wall and a self-closing door between the unit and the main dwelling. In San Gabriel, attached conversions under the city’s ADU ordinance still count as accessory dwelling units, which means the 4-foot side and rear setback rule applies to the addition if you extend any walls outward.
Detached Garage to Studio Apartment
A detached garage gives you full separation and privacy, but the existing structure was built for cars, not people. Most 1970s and 1980s San Gabriel garages sit on 3.5-inch unreinforced slabs that plan check will flag. Expect to pour a new 4-inch reinforced slab with a vapor barrier, and expect the city to require the structure to maintain the 4-foot minimum side and rear setback from the property line, which often means relocating the gas meter or a dryer vent before the building permit issues.
Garage Conversion Permit in San Gabriel

Garage Conversion Permit in San Gabriel is a required building permit issued by the city’s Building and Safety division, and it is not a one-page form. San Gabriel classifies a detached garage conversion as an accessory structure under its Residential Development Standards, which means the 4-foot side and rear setback applies – and so do the specific ADU ordinance rules on kitchens, utility metering, and occupancy. You cannot pull a permit over the counter without drawings, a site plan showing setbacks, and structural calculations for any slab or framing changes.
What Plan Check Flags
Plan check in San Gabriel regularly flags three things on garage conversions. First, the existing slab: older garages here have undersized or unreinforced footings that need an engineered fix. Second, utility placement: moving a meter or venting to meet the 4-foot setback triggers a separate utility relocation approval. Third, kitchen configuration: the city does not automatically allow a full kitchen and separate utility meter without verifying the development standards. Getting these cleared before demo starts is the difference between a permit issued in weeks and one stuck in corrections for months.
Working With a Contractor Who Pulls Permits
We pull the permits and schedule the inspections. That is how The Garrison Standard works – by the book. When plan check returns corrections, we answer them. When the inspector schedules, we are on site. A San Gabriel homeowner should never be asked to “handle the permit side” while a contractor builds. That is how permit boards stay blank and final inspections never happen. We hand you the permit number once it is issued and walk you through each inspection as it clears.
Trusted Brands We Service in San Gabriel
San Gabriel homeowners often research prefab ADU and modular options before they call us, and we speak that language. We work with Cover, Dvele, and Mighty Buildings, plus conventional builds using James Hardie siding. We can also take on a Tuff Shed-style structure and finish it as a permitted living space. The honest caveat: most detached San Gabriel garages were built for compact cars, not panelized modules. Before you order a prefab unit, we verify the garage door opening, ceiling height, and crane access on your lot. On narrow lots near Mission District or south of Las Tunas Drive, crane access is often the deciding factor. We would rather tell you now than after a module is sitting on a truck with nowhere to land.
Common Garage Conversion Contractor Problems We See in San Gabriel Homes
- Undersized slabs and footings. San Gabriel’s housing stock skews 1940s through 1980s, and most detached garage slabs from that era are 3.5 inches of unreinforced concrete. Plan check will flag it, and the fix – a new 4-inch reinforced slab – adds $8,000 to $15,000 after demo starts if you did not plan for it.
- Setback violations that trigger utility moves. The 4-foot side and rear setback rule for accessory structures in San Gabriel means existing gas meters, electrical panels, and dryer vents often sit in the way. Moving a gas meter runs $1,500 to $3,500, and it has to happen before the city issues the building permit.
- Prefab units that do not fit the lot. We see homeowners order a Boxabl or Mighty Buildings module only to find the garage opening is too low or crane access is blocked by a neighbor’s tree. On San Gabriel’s narrow lots, we verify dimensions and access before any order is placed.
- Unpermitted work from previous owners. Older San Gabriel garages sometimes have unpermitted electrical or plumbing already run to them. When that surfaces during plan check, it has to be corrected under current code before the conversion permit can move forward. That is added scope, and we put it in writing when we find it.
Pricing for Garage Conversion Contractor in San Gabriel, CA
A straight attached garage to bedroom conversion in San Gabriel runs $95,000 to $140,000. An attached garage to ADU with kitchen and bath runs $140,000 to $180,000. A detached garage to apartment or studio ADU runs $120,000 to $210,000. These are construction costs before permit fees, which in San Gabriel typically add $8,000 to $15,000 depending on scope. What moves the number: slab condition, utility relocations, whether you choose a prefab module or conventional framing, and the finish level of the kitchen and bath. We give you a written line-item price before any work starts, and that number does not change unless you change the scope. Call (361) 315-4177 for a free estimate.
We Also Serve Cities Near San Gabriel
Beyond San Gabriel, our crews regularly work in San Marino, Temple City, Alhambra, and Rosemead. The permitting rules and lot patterns change from city to city, but the way we work does not: written price first, permitted work, and a one-year written guarantee. If you are in a neighboring city and want to talk through a project, our Garage Conversion Contractor team can help you scope it. Read more about our work across Garage Conversion Contractor in San Gabriel and nearby areas.
Serving San Gabriel, CA - Our Local Coverage Area
We’re based in the San Gabriel 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 About Garage Conversion Contractor in San Gabriel
A detached garage conversion into an ADU in San Gabriel requires its own building permit; it is not covered under any existing main house permit. The city treats the detached garage as an accessory structure, and the permit application must include drawings, structural calculations, and a site plan showing the 4-foot setbacks. Call (361) 315-4177 if you want a written price that includes full permit handling.
In San Gabriel, plan check for a garage conversion typically takes 4 to 8 weeks, and construction from permit issuance to final inspection runs 10 to 16 weeks for a standard conversion. Total calendar time is usually 4 to 6 months. The biggest variable is plan check corrections – if the slab, setbacks, or kitchen configuration were not vetted up front, add weeks. We submit drawings that anticipate San Gabriel’s common corrections before the first plan check cycle. Call (361) 315-4177 and we will walk you through a realistic schedule.
Most San Gabriel garage conversions require an electrical panel upgrade because the existing panel cannot carry the added load of a kitchen and bath. The city’s building code requires a load calculation, and a 100-amp panel on an older home rarely passes. A 200-amp upgrade runs $3,500 to $6,500. We include this in the written price up front, not as a change order after demo. Call (361) 315-4177 for a line-item quote.
The most common structural upgrades in San Gabriel are a new 4-inch reinforced slab with vapor barrier to replace a cracked or undersized 3.5-inch slab, a structural ridge beam to tie new walls into the existing roofline, and footing reinforcement where plan check finds undersized foundations. On 1950s and 1960s garages near San Gabriel Boulevard, we also regularly see rotted sill plates that need replacement. These are engineered fixes that add cost, and we price them up front. Call (361) 315-4177 and we will look at your garage before you spend a dollar.
Yes, but only if the garage opening, ceiling height, and crane access work on your San Gabriel lot. Most detached garages here were framed for compact cars, not panelized modules. We work with Cover, Dvele, and Mighty Buildings, and before you order anything we verify the opening dimensions and crane path. If a module will not fit, we tell you and price a conventional build instead. Call (361) 315-4177 and we will walk the lot with you.
Call Fielding ADU Builders for Your San Gabriel Garage Conversion

We recently converted a 1980s detached two-car garage on a typical 50-foot-wide lot near Mission District into a 440-square-foot studio ADU for a multigenerational family. The existing slab was only 3.5 inches thick and cracked, so we poured a new 4-inch reinforced slab with a vapor barrier and tied the new 2×4 walls into the existing roofline using a structural ridge beam. We finished with James Hardie lap siding to match the main house, and the conversion passed its final inspection six weeks after the building permit was issued.
That project had the same scope questions every San Gabriel garage conversion raises: setbacks, slab, utilities, and a realistic timeline. We answered each one in writing before work started. If you are planning a garage conversion in San Gabriel, call (361) 315-4177 for a free estimate. Reed Calloway and the Fielding ADU Builders team will give you a written price first, pull the permits, and stand behind the work for a full year. That is The Garrison Standard, and it is the only way we build.
Written by Reed Calloway, Owner at Fielding ADU Builders, serving San Gabriel, CA.



