Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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AfterFast, Reliable Home Additions & ADU Across Long Beach
Home additions and ADU construction in Long Beach typically run $45,000-$130,000 for a full addition, with garage conversions landing between $30,000-$80,000 and a complete detached ADU between $90,000-$220,000. We’re Barrett & Sons Construction, owner-operated since 1998, and we build additions and ADUs across Long Beach every week. If you’re planning an addition in Belmont Heights, a garage conversion in Rose Park, or a detached ADU near El Dorado Park, call (877) 610-1318 for a free estimate and a written line-item scope before any work begins.
We know Long Beach’s housing stock the way only a local crew can. The 1920s Craftsman bungalows in Carroll Park and Rose Park sit on cripple-wall foundations that predate modern seismic standards. The post-war tract homes on the east side carry their own set of quirks. And the harbor-adjacent parcels in 90810 bring a soil condition no neighboring city deals with. That’s why our Home Additions & ADU team approaches every Long Beach project with the specific fix it needs, not a template from another county.
Why Barrett & Sons Construction Is Long Beach’s Preferred Home Additions & ADU Company
Tom Barrett founded this company in 1998 and his sons run the crews. You’ll see the same faces from the first estimate to the final inspection, and Tom answers his own phone. Long Beach homeowners have called us after a national outfit quoted one number on the phone and handed over a different bill at the door. That doesn’t happen here. Every scope, every allowance, every price change arrives as a written change order before a nail moves.
We pull permits and have inspections signed on every eligible Long Beach job. In the 90810 ZIP, that often means coordinating geotechnical soils reports as a permit condition. In the older districts, it means working with the city’s retrofit requirements. We’ve done both enough times that the inspectors know our work. And every completed job carries the 90-Day Done Right Promise in writing: if it’s not right, one call brings Tom back.
Calls are answered by 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 (877) 610-1318 about a home addition in Long Beach, you get a person who knows the difference between a craftsman in Rose Park and a mid-century tract home near Los Altos.
Our Home Additions & ADU Services in Long Beach
ADU Design & Permitting
Long Beach has its own permitting rhythm, and it’s not the same as Lakewood or Torrance. A garage conversion in 90804 can hit a different review queue than one in 90808. We handle the full design and permitting package: plans drawn, soils reports ordered where the subsidence zone mapping requires them, city comments answered, and permits in hand before construction starts. You’ll know what the city will require before you sign the contract.
Garage Conversion ADU
Converting a garage in Long Beach means dealing with the marine layer. A garage slab stays damp through summer because the coastal humidity never really dries it out. That’s why we use pressure-treated bottom plates elevated above the slab and stainless fasteners where others would use plain galvanized. A garage conversion ADU in Long Beach typically runs $30,000-$80,000 depending on whether you’re keeping the existing shell or rebuilding load-bearing walls.
New Detached ADU
A new detached ADU in Long Beach gives you the most control over materials and foundation. On harbor-adjacent parcels in 90810, that means a soils report and a foundation designed for expansive clay. On the east side, it means standard footings with proper drainage. We quote both ways so you can see exactly what your lot requires. Full builds run $90,000-$220,000 depending on size, finishes, and site conditions.
Junior ADU & Interior Conversion
A Junior ADU inside your existing Long Beach home is often the fastest path to a rentable unit. You’re not adding square footage, so the foundation typically doesn’t need a full upgrade. We convert spare bedrooms, enclosed porches, and interior spaces into self-contained units with their own kitchenette and bath. Interior conversions avoid the coastal-spec exterior costs entirely.
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 Long Beach
We install materials you can look up, not mystery brands off a van. For Long Beach ADUs and additions, we’re regularly working with Schluter for waterproofing in kitchenettes and baths, Grohe for fixtures, and GAF for roofing on additions that tie into existing shingles. These are brands chosen for how they hold up in coastal humidity. We stock common parts and trim locally, so a missing flashing or a special drain doesn’t stall your Long Beach project for a week.
Common Home Additions & ADU Problems We See in Long Beach Homes
- Rotted sill plates over cripple walls. Decades of marine-layer humidity soak the original 1920s timber, and the old galvanized anchor bolts rust to scale. A second-story addition on top of that is a problem waiting for a seismic event. We specify hot-dip galvanized hold-downs and stainless fasteners throughout the new load-bearing connections.
- Slab heave on expansive clay near the port. In the 90810 subsidence zone, the clay shifts seasonally. A new interior partition in a room addition will crack within two years if the job skipped a soils report and the slab moves under it. We don’t build without one where the city requires it.
- Roof-wall leaks on sunroom additions. A sunroom off the back of a 1940s infill home leaks at the intersection because the original unbraced cripple wall shifts under the added load, pulling the flashing apart. We brace the existing wall before we add anything to it.
- Rotted bottom plates in garage conversions. When bottom plates aren’t pressure-treated and elevated above the slab, the marine layer keeps the concrete damp and the wood rots within five years. We build them elevated and treated from day one.
Pricing for Home Additions & ADU in Long Beach, CA
Long Beach pricing splits into two specs: coastal-spec, which is built for salt air, humidity, and soils conditions, and inland-spec, which isn’t. The coastal-spec version of a job costs about 8-12% more at the contract stage. The inland-spec version costs more within a decade when the rot, the rust, and the slab movement show up. Here’s what Long Beach homeowners should expect for the main project types:
| Project | Typical Long Beach Range |
|---|---|
| Home Addition (coastal-spec materials) | $45,000-$130,000 |
| ADU Construction (full build) | $90,000-$220,000 |
| Garage Conversion ADU | $30,000-$80,000 |
| Second Story Addition (structural upgrade allowance) | $45,000-$130,000 |
Every estimate is free and written as a line-item scope. Every change order is in writing before work proceeds. Call (877) 610-1318 and we’ll walk your property with you, identify which ZIP code conditions apply, and give you a number that means what it says.
We Also Serve Cities Near Long Beach
Our crews serve Long Beach and the surrounding communities: Signal Hill, Lakewood, Carson, and Compton. If you’re just outside the city line, you still get the same Long Beach pricing and the same local knowledge. Dispatch and scheduling are coordinated from our Los Angeles office, with crews serving Long Beach locally every day.
Serving Long Beach, CA - Our Local Coverage Area
We’re based in the Long Beach 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 Long Beach
Because the 90810 ZIP sits inside the mapped subsidence zone left by the Wilmington Oil Field, where petroleum extraction caused harbor-area land to sink up to 29 feet. Long Beach and the county now require geotechnical soils reports as a standard permit condition on parcels in that zone. An identical ADU in Lakewood, which was never affected by oil field subsidence, would never trigger that requirement. The report itself typically adds a few thousand dollars to the permit phase and may shave days or weeks off the review once submitted. Call (877) 610-1318 and we’ll tell you whether your parcel is inside the mapped zone before you sign anything.
The 1933 Long Beach earthquake leveled much of downtown and triggered California’s first mandatory seismic building codes, but homes built before those codes often sit on original unreinforced concrete or cripple-wall foundations. Adding a second story to a 1920s craftsman in Rose Park or Carroll Park means the existing foundation and cripple walls have to be evaluated and typically braced or upgraded to carry the new load. That structural work can add $10,000-$25,000 to the project depending on what the inspector finds when the stucco comes off. We carry a structural upgrade allowance in every second-story estimate so the number is honest from day one.
The coastal-spec ADU runs about 8-12% more at the contract stage. That covers hot-dip galvanized or stainless hardware, marine-grade moisture barriers, pressure-treated and elevated bottom plates, and fasteners rated for salt air. The inland-spec version will quote lower, but in Long Beach’s marine layer the untreated bottom plates rot within five years and the galvanized bolts rust to scale. The cheap spec costs more within a decade. We quote coastal-spec as standard for Long Beach and show you the line items so you can compare honestly.
Because 90804 contains a high concentration of older multi-family and soft-story wood-frame buildings subject to Long Beach’s mandatory soft-story retrofit ordinance. When your garage conversion is part of or adjacent to one of those structures, the permit review can involve additional structural review and retrofit compliance checks that Torrance, which does not carry the same building stock or ordinance, would not require. We’ve moved enough conversions through the 90804 queue to know which documentation the city wants up front, and we submit the full package the first time to avoid resubmission delays. Call (877) 610-1318 for an exact timeline for your address.
In most Long Beach homes, yes. A Junior ADU that converts existing interior square footage, like a spare bedroom or enclosed porch, does not add new loads to the foundation the way a second-story addition or a new detached structure would. The city typically does not require a full foundation upgrade for an interior conversion unless the space has existing structural issues, like a sagging floor or a failed cripple wall. We’ll inspect the space, confirm what the city will require for your specific ZIP code, and give you a written scope before you commit.
Call Barrett & Sons Construction for Your Long Beach Home Addition or ADU
If you’re planning a garage conversion in Rose Park, a detached ADU in the 90810 subsidence zone, or a Junior ADU in your existing Long Beach home, get a free estimate from a company that’s been owner-operated since 1998. We’ll show you exactly what the city will require for your ZIP code, what the coastal-spec materials cost, and what the alternatives will cost you later. Every scope in writing, every permit pulled, every change order on paper before work starts. Call (877) 610-1318 today.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Long Beach since 1998.