Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Fast, Reliable Home Additions & ADU Across Anaheim
Adding square footage in Anaheim typically runs $45,000-$130,000 for room additions, and $90,000-$220,000 for a full ADU, with garage conversions landing between $30,000-$80,000. Those are real, line-item numbers for this market, not ballpark guesses from a call center in another state. If you live west of the 57 in a 1950s tract home near Pearson Park, your job has different engineering needs than a stucco hillside house off Weir Canyon Road in Anaheim Hills. We’ve built in both, and we know the difference before we ever pull a permit. Call (877) 610-1318 and we’ll come look at your lot, your foundation, and your plans. The estimate is free.
Why Barrett & Sons Construction Is Anaheim’s Preferred Home Additions & ADU Company
Tom Barrett started Barrett & Sons in 1998, and his sons run the crews on most days. That matters in a city like Anaheim, where the construction landscape splits between the Resort District and the chaparral-covered ridges of the hills. A national franchise sends whoever’s available. We send people who know that a west Anaheim addition on a 1956 slab foundation means one set of structural conversations, while a detached ADU in 92807 means WUI-compliant siding, ember-resistant vents, and a different conversation with the plan checker entirely.
Anaheim homeowners tell us the same stories: a company quoted one number, showed up with another, and stopped answering the phone after the third change order never got put on paper. Our policy is different and it’s written on every contract. Every scope change, every allowance adjustment, and every price revision arrives as a written change order before any work happens. If it’s not on paper, it doesn’t move forward. And when the job’s done, the 90-Day Done Right Promise covers it. One call brings Tom back.
We answer our own phone, 24 hours a day, seven days a week. Not a voicemail box. A live person. When you’re scheduling an Anaheim Hills ADU with the city’s fire marshal review layered on top of standard plan check, you want to talk to someone who’s navigated that exact process, not a dispatcher reading from a script.
Our Home Additions & ADU Services in Anaheim
Every project below includes permits pulled and inspections signed. The permit inspector works for you, not for us, which is why we treat inspection day like a deadline, not a hope. Here’s what we handle across Anaheim:
ADU Design & Permitting
Anaheim’s ADU ordinance follows state law but adds local layers in the hills. In 92807 and 92808, the California Fire Code’s High Fire Hazard Severity Zone requirements affect everything from vent mesh size to exterior wall assembly. We coordinate the architectural drawings, the structural engineering, and the city’s plan check process so you’re not left guessing which department wants what. A detached ADU in flatland Anaheim near Lincoln Avenue won’t face the same WUI review as one off Cannon Street, and we schedule for that difference.

Garage Conversion ADU
West and central Anaheim has thousands of 1950s and 1960s single-car garages with original wood framing and aging concrete slabs. Converting one into a rentable unit often means new shear walling, a moisture barrier under the new flooring, and electrical panel upgrades to handle the added load. We’ve converted garages all through 92804 and 92805, and we know which permits those neighborhoods trigger. This is the fastest path to an income-producing ADU if the existing structure is in workable shape.

New Detached ADU
Building a detached ADU in Anaheim Hills means building to fire-resistive standards most Orange County contractors rarely touch. The Santa Ana winds blow through the canyons each fall, and the city requires ember-resistant venting, Class A roofing, and defensible space coordination on hillside lots. In the flatlands, a detached ADU off West Street faces different rules: setback compliance, utility trenching across older lots, and soil testing on expansive clay. Anaheim’s climate runs hotter and drier than the coastal towns, so we size HVAC and insulation differently here than we would in Newport Beach.

Junior ADU & Interior Conversion
A junior ADU converts an existing bedroom or garage corner into an efficiency unit with its own entrance and cooking area. In central Anaheim’s post-WWII tract homes, these conversions often intersect with original asbestos-containing floor tiles and textured ceilings. Our crews are background-checked and uniformed on every visit, and they understand that abatement coordination is a routine part of the job here, not a surprise add-on. A JADU off Euclid Street has different plumbing and egress requirements than one in a newer floor plan near Yorba Linda Boulevard, and we scope each one to the actual house, not a template.
When an addition grows into a full kitchen or second bathroom, our Kitchen Remodeling in Anaheim and Bathroom Remodeling in Anaheim crews step in with premium brands like KraftMaid and Cambria. It’s the same contract, same written change orders, and same crew accountability.

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 Anaheim
We install windows from PGT and Simonton, and we specify them for Anaheim hillside ADUs where impact resistance and ember protection matter more than in the flatlands. If you’re building a second-story addition on a 1960s home near Modjeska Park, your window package should reflect the heat loads of an inland Orange County summer, not a coastal micro-climate. We stock and source what Anaheim jobs actually need, so you’re never waiting on a backordered mystery brand from a supply house two counties away.
Common Home Additions & ADU Problems We See in Anaheim Homes
- Expansive clay soil movement in Anaheim Hills. The hillside homes built in the 1980s and 1990s sit on graded lots with clay that shifts measurably in wet years. A new addition or detached ADU often requires engineered foundations or regrading before framing can begin.
- Original electrical panels on post-WWII tract homes. A 1956 house near La Palma Park was never designed for a modern ADU’s electrical load. Most additions and conversions in 92801-92806 need panel upgrades sized for the square footage, not the original fuse box.
- Asbestos-containing materials in ceilings and flooring. Textured ceilings, duct wrap, and vinyl floor tiles from the 1950s and 1960s are common in west and central Anaheim. Abatement coordination is a standard step in our Anaheim scope, not a change-order surprise later.
- WUI compliance gaps in hillside additions. Anaheim Hills falls within state-designated High Fire Hazard Severity Zones. A detached ADU or second-story addition there must meet ventilation, siding, and glazing standards that flatland builds skip entirely. This is the most costly local code layer most homeowners don’t know about until plan check returns.
Pricing for Home Additions & ADU in Anaheim, CA
Room additions in Anaheim run $45,000-$130,000 depending on whether you’re adding a single bed and bath or a full second-story with structural steel. A detached ADU lands between $90,000-$220,000, with Anaheim Hills WUI compliance typically adding 8-15% over flatland construction. Garage conversions run $30,000-$80,000, with the higher end reflecting panel upgrades, slab repair, and full kitchenette builds. Junior ADUs and interior conversions start near $45,000 when they involve new utility runs and egress work.
Our estimates are written and line-itemed before you sign anything. Every allowance is on paper, and every change order is issued in writing before work proceeds. No surprise invoices at the end. The “allowance that isn’t on paper” is how homeowners in Anaheim get burned, and we won’t do that to you. Call (877) 610-1318 to schedule a free estimate with Tom’s team.
We Also Serve Cities Near Anaheim
If you’re in Fullerton, Placentia, Orange, or Villa Park, we’ll bring the same written-change-order process and 90-Day Done Right Promise to your job. This page covers Home Additions & ADU in Anaheim specifically, but our crews serve the surrounding north Orange County communities too. We also offer Home Additions & ADU as a full service line, and you can read more about Home Additions & ADU in Anaheim on our city page.
Serving Anaheim, CA - Our Local Coverage Area
We’re based in the Anaheim 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 Anaheim
Room additions in Anaheim run $45,000-$130,000, with detached ADUs at $90,000-$220,000 and garage conversions at $30,000-$80,000. Hillside properties in 92807 and 92808 typically add 8-15% for fire-resistive construction and soil engineering. Call (877) 610-1318 for a written line-item estimate.
Yes, every eligible job includes permits pulled and inspections signed. In Anaheim Hills, that includes the fire marshal and WUI review layer. The permit inspector works for you, not for us, so we treat those inspections as non-negotiable deadlines.
Most detached ADUs in Anaheim take five to nine months from permit submission to final inspection. The Resort District design review layer and the hillside fire zone requirements each add time that flatland cities don’t face. We build that into the schedule so you know what to expect up front.
Yes. The WUI building standards, engineered foundations for expansive clay, and added plan check steps push hillside ADU construction 8-15% above comparable flatland projects. West Anaheim tract homes face different costs: older electrical panels, asbestos abatement, and original slab repairs. Both realities shape the final number, and both are written down before we start.
Every project carries the 90-Day Done Right Promise, written on the contract. If something isn’t done right, Tom Barrett comes back and makes it right, one call. We also honor the permanent 10% Senior & Veteran discount, $40 off any repair over $200, free second opinions on written estimates, and no trip charge inside the county. Call (877) 610-1318 to talk through your project.
Written by Tom Barrett, Owner at Barrett & Sons Construction. Serving Anaheim from 92804 to 92808, with permits pulled, change orders in writing, and a 90-Day Done Right Promise on every job since 1998.







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