A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable ADU Builders Across Commerce
Adding an ADU in Commerce usually means working with a small lot, a home built between the 1940s and 1960s, and a permit office that moves faster than most in Southeast Los Angeles. A detached backyard unit in Commerce typically runs $180,000 – $320,000, while a garage conversion lands between $95,000 and $165,000 before permit fees. Our ADU Builders team handles the whole thing: plans, permits, demo, framing, electrical, finishes. Call (213) 732-1415 and a live person picks up, day or night.
We know Commerce not as a map pin but as a working city. Bandini Boulevard. Eastern Avenue. The stretch of Slauson that runs past the outlets. The train tracks that split the city north from south. That matters when your lot slopes toward a storm channel, when your panel shares a feed with what used to be a commercial service, and when the plan checker asks about parking because you’re within a quarter mile of transit. You don’t want a builder learning Commerce on your dime. You want a crew that has already opened walls here.
Why Fielding ADU Los Angeles Is Commerce’s Preferred ADU Builders Company
Reed Calloway runs our ADU operation, and the way he runs it is simple: written price before work starts, background-checked crew in uniform on your site, and a one-year written guarantee on every project. That guarantee is The Garrison Standard, and it has been the operating rule inside Garrison Partners since 2006. If something fails inside 365 days, we return and fix it at no charge. Not a phone call where you chase a warranty. A written commitment.
Commerce homeowners call us because the math is honest. You approve a number on day one. That number is the number on the final invoice. No “we hit a snag” change order at the door. If we find cloth-wrapped wiring or a rotted sill plate when we open your walls, we price the fix in writing before we touch it. You decide. You sign. We build to The Garrison Code: show up in the window, price in writing, by the book, leave it clean, stand behind it for a year.
Dispatch and scheduling are coordinated from our Los Angeles office, but the crews who work in Commerce are local to this side of the 710. They know the plan check flow at the counter, the inspectors who cover the area, and the lot patterns that make Commerce different from West Hollywood or Gardena. That local knowledge shows up in the plans and in the build.
ADU Plans in Commerce
ADU Plans in Commerce start with a site visit, not a brochure. We measure the lot, check the zoning layer, confirm setbacks, and look at your existing panel before we draw a single line. A full plan set for a Commerce ADU, engineered and ready for submittal, typically runs $8,000 – $15,000 depending on whether you’re converting a garage, building detached, or adding a second story. That price includes structural engineering, Title 24 energy calcs, and the drawings the city needs to stamp your permit.
Commerce’s mixed residential/industrial zoning means some lots can tap commercial-grade utility connections. That’s a real advantage when you want a heat pump HVAC system or an EV charger in the ADU. We check for that during the plan phase, because it can shave days off the electrical scope and sometimes thousands off the final price.
What the city requires
Commerce follows the state’s ADU mandate but with local nuances. Parking waivers apply near transit, height limits reflect the compact semi-urban character of the city, and setbacks matter more when lots are 40 feet wide. We handle the plan check, the resubmittals, and the corrections. You get a plan set that passes the first or second round, not a stack of redlines you have to decode.
Site-specific drafting
A Commerce lot often has a long narrow driveway leading to a detached garage at the rear. That’s a prime ADU conversion candidate, but the plans have to account for the water table and drainage, not just the walls. Our drafting reflects what’s under the slab, not just what’s above it.
ADU Contractor in Commerce
An ADU Contractor in Commerce has to handle more than framing and drywall. The city’s older housing stock, mostly wood-frame stucco from the 1940s through the 1960s, hides the conditions that move budgets: outdated panels, undersized foundations, termite damage where the slab meets the stem wall. When you open walls on a Commerce ADU project, you find things. We expect that and we price for it. A full build, from demo to final inspection, typically runs $250 – $450 per square foot before permit fees, depending on the scope.
That range is honest. A garage conversion with a clean slab and a simple panel lands lower. A second-story addition over an attached garage on a 1940s home lands higher, because the foundation and framing work is heavier. Either way, you get a written price before we start, with allowances written into the contract for the unknowns we know are coming.
Opening walls the smart way
We inspect before we quote. That means a crawl under the house, a look at the panel, a check of the rim joists, and a moisture reading near the slab. Commerce sits on the LA Basin’s alluvial plain and parts of the city have a high water table. Water wicks up through slabs and into sill plates. You can’t see that from the driveway. We look.
Change orders, done right
When we do find something, the change order is written, priced, and signed before we pick up a tool. No verbal “we’ll figure it out later.” No surprise at the end. You approve the number, then we build. That’s the Fielding way, and it’s why homeowners who have been burned once tend to call us the second time.
Trusted Brands We Service in Commerce
We don’t push one build method on every Commerce lot. We work with prefab and modular platforms including Cover, Dvele, Mighty Buildings, and Boxabl, which can shorten on-site time and reduce waste on tight lots. For conventional builds, we use James Hardie siding and standard stick framing, and we’re comfortable with Tuff Shed style structures for studio conversions. If you’re weighing a prefab ADU against a conventional build, we’ll walk you through the real cost difference on your specific lot, not a generic brochure. You make the call with real numbers in front of you.
Common ADU Builders Problems We See in Commerce Homes
- Undersized electrical panels. Most Commerce homes from the 1950s and 1960s have a 100A panel, and many were wired when the city’s industrial tax base shared infrastructure differently. When the ADU’s AC and laundry start up, breakers trip. We scope the panel for 100A to 200A before the first rough inspection.
- Failed waterproofing at the slab-to-stem-wall joint. The water table in parts of Commerce sits high, and older slabs weren’t detailed for it. Moisture wicks up, sill plates rot, and a garage conversion becomes a foundation repair. We test for this early and write the allowance into the contract.
- Cloth-wrapped wiring and termite damage. A 1950s stucco home off Eastern Avenue will almost always reveal cloth-wrapped conductors and often termite-damaged framing at the sill plate. The time to budget for that is before you sign the contract, not after the drywall is off.
- Parking requirements near transit. Commerce offers parking waivers for ADUs near transit stops. If you don’t know that going in, you might design a project that triggers off-street parking you don’t have room to build. We check the waiver before we draw the site plan.
Pricing for ADU Builders in Commerce, CA
Here are the ranges we quote in Commerce, as of the last 12 months, before permit fees:
- Detached ADU: $180,000 – $320,000
- Garage conversion: $95,000 – $165,000
- Second-story addition over attached garage: $220,000 – $380,000
- Junior ADU (within existing footprint): $70,000 – $120,000
- Prefab or modular ADU (including site work and foundation): $160,000 – $280,000
What moves the number in Commerce specifically: lot width and access, panel condition, foundation condition, and whether the city grants a parking waiver near transit. You’ll get a line-item quote, not a round guess. Call (213) 732-1415 for your free estimate. No charge for the visit, no obligation to sign.
We Also Serve Cities Near Commerce
Our crews work throughout Commerce and the surrounding cities. If you’re in Los Angeles, West Hollywood, Beverly Hills, or Gardena, the same written price policy and the same one-year guarantee apply. The plan check counter changes. The standard doesn’t.
Serving Commerce, CA - Our Local Coverage Area
We’re based in the Commerce 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 ADU Builders in Commerce
Cloth-wrapped wiring, almost every time. Then termite damage at the sill plate, then failed waterproofing where the slab meets the stem wall. That’s why we write allowances into the contract before we start, and why we inspect before we quote. The inspection is free. Call (213) 732-1415 and we’ll walk the property with you.
Yes, in most cases. Commerce offers parking waivers for ADUs near transit stops, which many of these rear-lot garages qualify for. Even without the waiver, a detached garage conversion often works when the driveway itself remains as the required parking space. The plans simply reflect the existing driveway instead of trying to add a new one. We check the waiver eligibility before we draw anything.
Because Commerce’s mixed residential/industrial zoning means some homes share infrastructure with former or adjacent commercial service. A heavier feed can already be in place, which cuts the time and cost of a 200A upgrade. We verify what’s at the pole and the meter before we scope the panel.
The city will ask for a structural letter or calc on the existing framing once walls are open, plus documentation of the foundation condition. If we find rot or termite damage, the fix gets engineered and permitted as part of the ADU scope, not as a separate job. That’s why our plans anticipate what we’ll find, rather than drawing the ideal and hoping the walls are clean.
It’s realistic, but it’s a heavier build. The garage slab and stem walls on a 1940s home usually need reinforcement, and the framing above gets engineered for the new load. That typically pushes the cost to $220,000 – $380,000 before permit fees. If the budget doesn’t support that, a garage conversion at $95,000 – $165,000 delivers the same rental or family space without the structural lift. We’ll price both options in writing, and you choose.
Written by Reed Calloway, Owner at Fielding ADU Los Angeles, serving Commerce and the surrounding cities.
