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 La Mirada
Adding square footage to a La Mirada home usually starts with one uncomfortable realization: the house you bought 20 or 30 years ago doesn’t fit anymore, but the lot still does. Whether that means a detached ADU off the back of a 1962 ranch near Behringer Park, a garage conversion on a quiet cul-de-sac in 90638, or a second story above the original post-and-beam frame off Santa Gertrudes Avenue, the question is the same: who do you trust to pull the permits, pour the foundation, and not hand you a surprise invoice at the end? Barrett & Sons Construction has been doing Home Additions & ADU work for homeowners across La Mirada who want the job done right, in writing, with someone they can find again if something isn’t. Call (877) 610-1318 for a free estimate.
Why Barrett & Sons Construction Is La Mirada’s Preferred Home Additions & ADU Company
For 29 years, Tom Barrett has run this company the way he runs a job site: his name is on the truck, his sons are on the crew, and every price change shows up as a written change order before a single nail moves. Homeowners in La Mirada who’ve been burned by a national outfit before tell us the same thing: the quote they got on the phone wasn’t the bill they got at the door. We don’t work that way. The scope goes in writing. The allowances go in writing. The permit inspector works for you, not for me, and I like it that way.
We answer our own phone at (877) 610-1318, 24 hours a day. Not a voicemail box. Not an out-of-state call center. When you call about an ADU on Stage Road or a room addition near La Mirada Regional Park, you talk to someone who can actually answer your question. We also back every job with the 90-Day Done Right Promise, written on the contract: if it isn’t done right, one call brings Tom back. We’d rather come back and fix a door jamb than lose your trust over a phone call.
And because La Mirada’s housing stock is so uniform, we’ve seen the same conditions repeat for years. The original 100-amp panels. The cast-iron drain lines under the slab. The low-slope roof framing from the Chevron Land & Development tract era. When a crew has retrofitted shear walls off Foster Road, they walk onto the next job two blocks away and recognize the framing. That’s not luck. It’s what happens when you work in the same three ZIP codes long enough.
Our Home Additions & ADU Services in La Mirada
ADU Design & Permitting
Most La Mirada ADU projects start with a question about what the city and county will actually approve, and the answer is usually more flexible than homeowners expect. Because La Mirada sits in the Whittier Fault corridor, every structural addition triggers LA County seismic compliance review. We handle that: the drawings, the structural calcs, the energy compliance, the permit submittals, and the inspector sign-offs. You don’t chase paperwork. We do. It’s part of the job, not an add-on fee.
Garage Conversion ADU
Converting a garage into an ADU in La Mirada is one of the fastest ways to add a rentable unit or a private space for an aging parent without changing the footprint of the house. Most of these garages sit on the same poured-concrete slabs poured in the early 1960s, which means we’re checking for existing cracks, re-routing plumbing, and often upgrading that original electrical panel before the finish work starts. A typical garage conversion in La Mirada runs $30,000-$80,000 depending on whether you’re keeping the existing structure or rebuilding walls to meet current energy codes.
New Detached ADU
A new detached ADU gives you a clean slate: a fresh foundation, modern insulation, separate utility connections, and no compromises from a 60-year-old frame. In La Mirada, that also means submitting plans that account for hot inland summers and the seismic requirements specific to this slice of the LA Basin. These projects typically run $90,000-$220,000 in this market, and we’ll put every allowance and every change order in writing before work begins. No surprises on the final walkthrough.
Junior ADU & Interior Conversion
If you have an extra bedroom, a large den, or an attached space with a door to the outside, a junior ADU is the most cost-effective legal unit you can create in La Mirada. These conversions typically stay within the existing footprint, which keeps costs down and speeds up permitting. What they require, though, is an honest look at the existing walls, wiring, and the path to add a small kitchenette and a private entrance. We’ll tell you what’s possible, what the city will require, and what it will cost before you sign anything.
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 La Mirada
We install materials you can look up, not mystery brands off a van. When a La Mirada addition calls for a paver patio or a walkway to a new ADU entrance, we work with Belgard, Techo-Bloc, and Cambridge Pavers because they hold up under the inland summer heat and they have verifiable warranties that don’t disappear when the truck pulls away. For roofing on sunroom additions and enclosed patios, count on GAF and CertainTeed. We’d rather lose a bid than put a brand nobody’s heard of on your home.
Common Home Additions & ADU Problems We See in La Mirada Homes
- Original 100-amp electrical panels. Nearly every home built in the Chevron Land tract era came with a 100-amp service, and the minute you add an ADU with a mini-split, a stove, and a washer-dryer stack, you’re over capacity. We plan for the panel upgrade from day one, not as a surprise mid-project.
- Cast-iron and galvanized drain lines under the slab. Adding a kitchenette or a full bath to a La Mirada addition often means cutting into a slab that still has original 1960s drain pipe. If it’s compromised, the inspector will flag it, and we’d rather scope it before we pour anything.
- Low-slope rooflines and UV degradation. Summer temperatures here regularly push into the mid-to-upper 90s, and the membrane on a low-slope ranch roof takes a beating. When a sunroom or enclosed patio ties into the existing roofline, the transition has to be right or you’ll chase leaks every winter.
- Seismic shear compliance. La Mirada’s proximity to the Whittier Fault corridor means any structural addition triggers a seismic review. The permit inspector works for you, not for me, and when the shear walls are done right, you don’t think about them again. When they’re done cheap, you feel it in every aftershock.
Pricing for Home Additions & ADU in La Mirada, CA
A home addition in La Mirada typically runs $45,000-$130,000, and a full new detached ADU runs $90,000-$220,000. Garage conversions sit in the $30,000-$80,000 range, while a junior ADU or interior conversion can start lower because the shell already exists. What moves the number is the structural work: the panel upgrade, the seismic shear walls, the slab plumbing. In La Mirada, those costs are fairly predictable because the housing stock is so consistent. We give free, written estimates with line-item pricing so you can see exactly where your money goes. Call (877) 610-1318 to schedule yours.
We Also Serve Cities Near La Mirada
Beyond La Mirada, our crews work regularly in La Mirada‘s neighboring communities: South Whittier, East La Mirada, Buena Park, and Norwalk. We also handle Kitchen Remodeling in La Mirada and Bathroom Remodeling in La Mirada when you’re already planning an addition and want the whole scope handled by one crew that answers to one name.
Serving La Mirada, CA - Our Local Coverage Area
We’re based in the La Mirada 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 La Mirada
A garage conversion or junior ADU in La Mirada typically runs 3 to 6 months from first drawings to final inspection. A new detached ADU takes 6 to 10 months depending on the seismic review and your site’s existing utility connections. We’ll give you a written timeline before work starts, and when something changes, you’ll get a written change order, not a surprise conversation. Call (877) 610-1318 and we’ll walk through your specific project schedule.
Yes, on every eligible job. Permits get pulled, inspections get signed, and the inspector works for you, not for me. If a contractor in La Mirada tells you permits are optional, that’s your sign to find a different contractor. Call (877) 610-1318 for a free estimate that includes what’s required and what it costs.
Not without a written change order you’ve approved first. The scope goes in writing, the allowances go in writing, and any change goes in writing before work proceeds. An allowance that isn’t on paper is a surprise waiting for a date, and we don’t do surprises. That’s what the 90-Day Done Right Promise is built on.
La Mirada pricing runs close to the LA County average because the housing stock is so uniform, but the seismic review required here can add time and engineering cost over an Orange County jurisdiction just across the city line. A typical new detached ADU in La Mirada runs $90,000-$220,000, while a garage conversion runs $30,000-$80,000. For an exact number on your lot, call (877) 610-1318, and you’ll get a written, line-item estimate.
Yes. We work across 90637, 90638, and 90639, from homes near Biola University down to the neighborhoods along Imperial Highway and out toward the La Mirada Country Club area. If you’re in La Mirada, we answer the phone and we show up. Call (877) 610-1318 and we’ll schedule your free estimate.
Call Barrett & Sons Construction for Your La Mirada Home Addition or ADU
If you’ve been sitting on plans for an ADU or an addition in La Mirada, the next step is a conversation, not a commitment. Call (877) 610-1318 and you’ll get a live person, a free written estimate, and a straight answer about what your home will actually require. We serve Home Additions & ADU in La Mirada with the name on the truck and a promise on the contract.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving La Mirada since 1998.