Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Fast, Reliable Home Additions & ADU Across Florence-Graham
Home additions and ADU construction in Florence-Graham typically run between $45,000 and $130,000 for a room addition or garage conversion, with new detached ADUs ranging from $90,000 to $220,000 depending on square footage and site conditions. Those numbers reflect a market where most of the housing stock dates back to the 1920s through the 1950s, which means nearly every project starts with some degree of foundation work, electrical upgrades, or permit cleanup. If you’re weighing a room addition against a garage conversion or a new backyard ADU, we can walk you through the real numbers over the phone. Call (877) 610-1318 and we’ll tell you what’s realistic for your lot before anyone measures a thing.
Florence-Graham sits in an unusual spot for construction work. You’re surrounded by incorporated cities like Huntington Park, Walnut Park, Willowbrook, and South Gate, but your permits run through the LA County Department of Public Works rather than LADBS. That single fact changes plan-check timelines, fee schedules, and inspection flow, and it’s something we navigate weekly for homeowners across the 90001 ZIP. Our Home Additions & ADU team knows which questions the County will ask before they ask them.
Why Barrett & Sons Construction Is Florence-Graham’s Preferred Home Additions & ADU Company
Tom Barrett started this company in 1998, and his sons run the crews. When we say the name on the truck is the name on the contract, we mean it literally. Homeowners in Florence-Graham don’t want a franchise dispatcher sending strangers to their house. They want a contractor whose reputation lives in the same neighborhoods they do. Tom’s name, address, and license number are published and verifiable. Look us up before you sign anything.
We’ve done enough work in Florence-Graham to know what’s behind the walls before we open them. Wood-frame bungalows from the 1920s and 1930s with original galvanized supply lines. Garages converted without permits decades ago. Rear units added by a previous owner’s cousin. When we walk a job site near Graham Avenue or Slauson Avenue, we’re not surprised by any of it. We plan for it. That’s the difference between a fixed price that holds and a “surprise” invoice at the end. Every scope change we issue comes as a written change order before work proceeds. Nothing happens that you haven’t seen on paper first.
We answer the phone. A live person, 24 hours a day, seven days a week. Not a voicemail box, not an out-of-state call center. When you call about your project in Florence-Graham, you get someone who knows what you’re asking. And if it’s not done right when we finish, one call brings Tom back. That’s the 90-Day Done Right Promise, and it’s written on every contract.
Our customers in Florence-Graham and across South LA consistently point to the same things: the permit inspector signs off because the work is done the way the County wants it done, the price we quoted is the price they paid, and the crew showed up when we said they would. We don’t run from the unincorporated-area paperwork. We’re used to it, and we’ll tell you exactly what it costs and how long it adds.
Our Home Additions & ADU Services in Florence-Graham
ADU Design & Permitting
Getting from “I want an ADU” to a signed permit in Florence-Graham means navigating LA County Department of Public Works, not LADBS. The plan-check queue, the fee schedule, the inspection process, all of it differs from what contractors who work a few blocks north in the City of LA are used to. We prepare plans, handle structural calculations, and manage the County submittal and revisions from start to finish. You won’t chase paperwork. We’ll track it and tell you where things stand.

Garage Conversion ADU
Florence-Graham has one of the highest concentrations of garage conversions in South LA, and a lot of them were done without permits somewhere along the way. Converting an existing garage into a legal ADU often means reinforcing the foundation, upgrading the electrical panel, replacing the garage slab if it’s too thin for residential use, and bringing every element to current code. We handle the entire conversion, including County permit legalization if your garage already has unpermitted finishes. A garage conversion in Florence-Graham typically runs $30,000 to $80,000 depending on what’s already there.

New Detached ADU
Detached ADUs on the flat lots around Florence-Graham need attention to two things most areas don’t worry about: seismic bracing requirements and the urban heat island factor. Your lot sits in the Los Angeles Basin with poor air circulation, so we plan for cool-roof materials and proper insulation from day one. New detached ADUs in the 90001 ZIP generally run $90,000 to $220,000, with the biggest variables being square footage, foundation condition, and utility trenching distance.

Junior ADU & Interior Conversion
Many older bungalows in Florence-Graham have enclosed porches or former service rooms that can become junior ADUs without the footprint of new construction. The trick is determining whether the existing framing, floor structure, and wiring can support the conversion legally. On pre-war homes with original subflooring and aging electrical systems, sometimes the shortest path is selective demolition and rebuilding properly. We’ll give you an honest read. Often a junior ADU is the most affordable path to rental income or family housing on your property.

Room Additions, Second Story Additions, Sunrooms & Enclosed Patios
Room additions on Florence-Graham’s small lots usually mean one of three things: building up, building out into the rear yard, or enclosing and conditioning existing patio space. Second-story additions nearly always trigger foundation evaluation because the original pier-and-beam setups under many 1930s bungalows weren’t engineered for the added load. Sunrooms and enclosed patios come with their own County requirements for glazing, egress, and thermal performance. We’ll tell you what’s feasible on your specific lot before you spend money on plans that won’t pass review.
When a kitchen or bath is part of the addition, we handle that too. See our Kitchen Remodeling in Florence-Graham and Bathroom Remodeling in Florence-Graham pages for how we approach interior work in the area’s older homes.

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 Florence-Graham
We install materials you can look up, not mystery brands off a van. For kitchens and baths inside Florence-Graham additions, we carry KraftMaid and Cambria. On roofs, GAF and CertainTeed. Windows come from Andersen and Marvin. Hardscapes run Belgard and Techo-Bloc. We also work with Schluter and Grohe on waterproofing and fixtures where the project calls for it. If a brand matters to you, say so when you call. We’ll tell you whether it fits the budget and the County’s requirements. We keep local parts availability in mind for Florence-Graham jobs so a backordered fixture doesn’t stall your final inspection.
Common Home Additions & ADU Problems We See in Florence-Graham Homes
- Unpermitted garage conversions and rear units. Decades of informal densification mean many Florence-Graham properties carry unpermitted living space. Legalizing it requires bringing framing, electrical, plumbing, and egress up to current County code. We do this routinely, and we’ll tell you upfront what’s fixable and what isn’t.
- Cripple wall and foundation deficiencies. The area sits in a high seismic hazard zone. Pre-war bungalows with short cripple walls and minimal bolting often need retrofit work before an addition can be tied in. The County will flag it, and we’d rather tell you before plan check does.
- Undersized electrical panels and aging galvanized lines. Adding an ADU or second story usually means adding a subpanel or upgrading the service entirely. Original 60-amp panels and galvanized supply lines from the 1930s won’t pass today’s load calculations.
- Urban heat island in the flat Basin. Florence-Graham gets significantly hotter than hillside or coastal communities on summer afternoons. New additions without proper insulation, cool-roof materials, or shading end up as rooms nobody wants to sit in. We plan for it from the start.
Pricing for Home Additions & ADU in Florence-Graham, CA
Here’s what we quote in Florence-Graham, in writing, every time:
- Room addition or home addition: $45,000-$130,000
- ADU construction (new detached): $90,000-$220,000
- Garage conversion ADU: $30,000-$80,000
What moves the number: your lot’s setback situation, foundation condition, seismic retrofit scope, distance from the street for utility trenching, and the finish level you choose. We submit every scope, every allowance, and every price change as a written document before work begins. You won’t get a “final invoice” that looks different from the contract. Call (877) 610-1318 for a free estimate. We’ll walk the property, listen to what you want, and hand you numbers you can take to the bank.
We Also Serve Cities Near Florence-Graham
Our crews work across South LA, including Huntington Park, Walnut Park, Willowbrook, and South Gate. If you’re in one of those neighboring communities, the same County permit knowledge applies, and the same crew standards hold. See our Home Additions & ADU in Florence-Graham page for specifics on how we serve this area, or call (877) 610-1318 and tell us where your project sits.
Serving Florence-Graham, CA - Our Local Coverage Area
We’re based in the Florence-Graham 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 - Home Additions & ADU in Florence-Graham
A home addition in Florence-Graham typically runs $45,000 to $130,000 depending on size, foundation work, seismic retrofit requirements, and finish level. That range reflects the area’s older housing stock and LA County permit process. Call (877) 610-1318 for an exact quote, the estimate is free.
Yes. Every eligible Florence-Graham ADU project we take on includes permits pulled through the LA County Department of Public Works and inspections signed before we call it done. The permit inspector works for you, not for us, and we like it that way. If a contractor tells you permits are optional in unincorporated LA County, walk away.
In most cases, yes. Florence-Graham has one of the highest concentrations of unpermitted garage conversions in South LA, and we’ve brought many of them into Code compliance. The process involves a County application, structural and electrical reviews, and corrective work to bring everything current. We’ll assess yours and give you a written scope before anything starts.
Florence-Graham runs through the LA County Department of Public Works, not LADBS. That means a separate plan-check queue, different fee schedule, and inspection protocols than contractors working a few blocks away in the City of LA deal with. We know the County’s process and plan for the added lead time from day one.
Every job carries our written 90-Day Done Right Promise. If it’s not done right, one call brings Tom Barrett back to make it right. That’s in the contract, not buried in fine print. Call (877) 610-1318 and we’ll show you exactly what it says.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Florence-Graham and the surrounding South LA communities.







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