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 Lakewood
A home addition or ADU in Lakewood runs $45,000-$130,000 for a room addition and $90,000-$220,000 for a new detached ADU, depending on what’s hiding behind your 1950s walls. Most jobs here take 4-9 months from permit to final inspection. If you’re planning a garage conversion or second-story addition in Lakewood, call (877) 610-1318 and we’ll walk the property and give you a written line-item estimate before anything gets signed.
Lakewood is different from any city we work in. Nearly every house here was built between 1950 and 1954, which means your home and your neighbor’s home and the house four blocks over all share the same original materials and the same failure timeline. That’s not a problem, it’s actually a map. We know what’s in your walls before we open them because we’ve opened a thousand just like them across 90711, 90712, 90713, and 90714. We’re Home Additions & ADU builders who grew up on this housing stock, and we answer the phone 24 hours a day.
Why Barrett & Sons Construction Is Lakewood’s Preferred Home Additions & ADU Company
Barrett & Sons has been an owner-operated construction company since 1998, started by Tom Barrett and run today with his sons on-site most days. When you hire us for a home addition or ADU in Lakewood, you get Tom’s name, his address, and his license number before you sign anything. Look us up. We’d rather you did.
What you’ll find when you search: permits pulled and inspections signed on every eligible job, price changes in writing before a single nail moves, and a 90-Day Done Right Promise written on the contract. If something’s not right, one call brings Tom back. We don’t hand your project to a dispatcher who sends strangers to your house; the crew members who carry the Barrett & Sons name are background-checked and uniformed on every visit. Lakewood neighbors talk, and after 29 years of this work, our name holds up at the Saturday hardware store.
Our Home Additions & ADU Services in Lakewood
ADU Design & Permitting
Lakewood’s planning and building department has gotten easier on ADUs in recent years, but the Catch-22 is structural: before they’ll approve a permit, they want to know the existing house can handle the added load. That means a sewer lateral scope, a foundation check on that 1950s slab, and an honest look at your original 60-amp panel. We handle the entire permit package, including drawings, energy calcs, and all revisions. A garage conversion or detached ADU in Lakewood should be designed around what’s inside your walls, not just what fits in the backyard.
Garage Conversion ADU
Lakewood garages are small, attached, and framed with the same postwar lumber as the house. Converting one into a permitted ADU usually costs $30,000-$80,000, and the big variables are the panel upgrade, the sewer lateral condition, and whether the slab was poured with a proper footing. We recently did a garage conversion off Centralia Street where the original Orangeburg sewer lateral had collapsed into an egg-shaped mess, discovered only after we scoped the line as step one before pulling permits. We replaced it with ABS, upgraded the panel to 200 amps, and used hot-dip galvanized anchor bolts for the new cripple-wall bracing, then signed off on the final inspection without a single change order.
New Detached ADU
Building a detached ADU in a Lakewood backyard runs $90,000-$220,000, depending on square footage, utility trenching, and finish level. Postwar lots here are deeper than they are wide, so most ADUs we build are long and narrow, taking advantage of the lot depth. Expect a new foundation, new electrical subpanel from the upgraded main, and a dedicated sewer lateral or tied-in line that passes inspection. A permit inspector in Lakewood will check every one of these, which is exactly why we pull permits on every eligible job. The inspector works for you, not for me, which is why I like him.
Junior ADU & Interior Conversion
A Junior ADU, usually under 500 sq ft built inside the existing footprint of the house, is one of the smartest moves in Lakewood. You’re converting an attached room, a rear extension, or part of a large original bedroom. The benefit is speed and cost: $45,000-$130,000 gets you a self-contained unit with a kitchenette and bath, often without the full separate utility service a detached ADU requires. But the same material realities apply: galvanized supply lines, 60-amp service, and original framing all come into play when you open the wall.
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 Lakewood
For Lakewood jobs, we specify materials that survive the LA Basin salt air and the hard water coming through original galvanized lines. Window frames from Simonton, Ply Gem, and PGT hold up far better than the original steel casements on these houses, which have been rusting at the corners since Eisenhower was in office. Door hardware and anchor bolts get hot-dip galvanized or stainless spec. We don’t stock mystery brands off a van; we purchase what we install from local suppliers, so warranty parts arrive within days, not weeks. Lakewood homeowners can look up every material we name.
Common Home Additions & ADU Problems We See in Lakewood Homes
- Orangeburg sewer laterals. Lakewood’s original sewer lines were a bituminous fiber pipe that collapses after 50-70 years. Every single permit we pull starts with a camera scope of the lateral, because mid-renovation trenching and permit revisions are the most expensive surprise a homeowner can hit.
- Galvanized steel water supply lines. Original 1950s galvanized pipes corrode from the inside. When we restore full water pressure after an ADU rough-in, a weakened line can rupture and flood the slab before drywall goes up. We spot-check these lines on every Lakewood visit.
- 60-amp electrical services. Roughly 80% of Lakewood homes still run on the original 60-amp panel. Adding an ADU or second-story addition without upgrading the panel means breakers tripping and inspection failures. Budget for a 200-amp panel upgrade as part of the job.
- Cripple-wall and foundation bolt work. Lakewood sits in a seismically active corridor, and pre-modern-code 1950s slabs almost never have adequate anchor bolts or bracing. A permitted addition or ADU triggers retrofit requirements, and doing it during the project costs a fraction of what it costs to do later as a standalone fix.
Pricing for Home Additions & ADU in Lakewood, CA
Here’s what we see quoted and built across Lakewood’s four ZIP codes, and the numbers we stand behind in writing:
| Project | Typical Range in Lakewood |
|---|---|
| Home Addition | $45,000-$130,000 |
| Garage Conversion ADU | $30,000-$80,000 |
| New Detached ADU | $90,000-$220,000 |
What drives the gap between the low and high end? Whether the panel and sewer lateral need full replacement, the condition of the slab and footings, and the finish level you want. A bare-bones garage conversion with an existing 200-amp panel and a good lateral lands at the bottom of the range. A detached ADU with trenching, a new subpanel, a full kitchen, and upgraded windows lands at the top. Either way, the number we quote is the number we build to, with allowances in writing and any scope change documented before work proceeds. An allowance that isn’t on paper is a surprise waiting for a date.
Call (877) 610-1318 to schedule your free estimate. We walk the property, map the existing conditions, and give you a written line-item quote with no trip charge inside the county.
We Also Serve Cities Near Lakewood
Our crews work Lakewood every week, and we also serve Signal Hill, Bellflower, Long Beach, and Paramount. Each city has its own planning department and its own stock of postwar or mid-century homes, but the approach stays the same: pull permits, inspect the existing conditions, and put every price change in writing. If you’re in one of those neighboring cities, call (877) 610-1318 and ask for the same free estimate.
Serving Lakewood, CA - Our Local Coverage Area
We’re based in the Lakewood 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 Lakewood
Lakewood’s entire residential stock was built in the same four-year window, and the original Orangeburg sewer laterals are all hitting end-of-life right now. The building department knows this. An inspector will ask about the lateral before signing off on an ADU permit because a collapsed line under the addition is a guaranteed failure. A scope costs a few hundred dollars before the permit is pulled; a mid-project trench repair costs thousands and triggers permit revisions. Call (877) 610-1318 and we’ll scope the line as step one.
In most Lakewood homes, yes. The original 60-amp service from the 1950s cannot legally or safely support a permitted ADU. You’ll need a 200-amp panel upgrade, which we include in the written scope before work begins, not as a change order after the walls are open. Estimates are free, call (877) 610-1318.
Because nearly every home in Lakewood needs the same set of pre-ADU upgrades: a 200-amp panel, a sewer lateral replacement or spot repair, and often galvanized water line replacement and cripple-wall bracing. Long Beach and Cerritos have a more mixed housing stock, and many homes there were built later with fewer legacy materials. The Lakewood price reflects the generational condition of the original 1950-1954 build, not a markup. Call (877) 610-1318 for an exact estimate.
All four: 90711, 90712, 90713, and 90714. The original tract spread across every one of them in the early 1950s, so the galvanized lines, the 60-amp panels, and the Orangeburg laterals are distributed uniformly. Whether you’re off Centralia Street or near Mayfair Park, budget for the same surfacing costs, and we’ll map them before the first permit is pulled.
The short answer is an engineering letter, a foundation inspection, and often a seismic retrofit. A second-story addition adds load a 70-year-old slab was never designed to carry in a modern code sense. Expect the plan check to require structural verification, and likely anchor bolt and cripple-wall upgrades to bring the lower story into current seismic compliance before the addition can be built. We pull the permits and handle the retrofit as part of the job, with inspections signed off at every stage.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Lakewood and Los Angeles County since 1998.