The Best ADU Contractor in Anaheim, CA

Most Anaheim homeowners sitting on an underused garage or a stretch of backyard have no idea what that footprint could actually become for their family.

The ADU Contractor Anaheim Homeowners Keep Coming Back To

We’ve been building custom ADUs across Southern California long enough to know that every property tells a different story.

Anaheim, with its mix of mid-century homes, varied lot configurations, and a housing market that keeps pushing people to maximize what they already own, is exactly the kind of city where thoughtful ADU development changes lives.

We know these neighborhoods. We’ve walked dozens of yards just like yours and helped homeowners figure out what’s genuinely possible on their property.

Building an accessory dwelling unit is a significant commitment, and the company you choose shapes the entire experience. Cornejo’s Builders was built around the idea that contractors should be communicators first.

We tell you what’s happening, when it’s happening, and why, throughout the entire construction process. Twenty-four completed ADU projects in four years reflect how many families in Anaheim and across LA County trusted us with something they genuinely cared about.

We work on everything from detached ADUs and garage conversions to granny flats, home additions, second-story builds, and attached garages. Whatever your property has to offer and whatever your family needs, we’ve probably tackled something very similar a few streets away.

Alexsander Cornejo – Owner of Cornejo Builders

Hi, I’m Alexsander Cornejo, the owner and founder of Cornejo’s Builders. I started working in the remodeling and construction industry right out of high school, in 2009.

With Cornejo’s Builders, the goal is to give back to the city I grew up in. I want to send a message of hope and inspiration: any dream can be achieved, no matter where you come from, if you put in enough work and dedication.

ADUs We’ve Built for Anaheim, CA, Families

Browse through our completed ADU projects and get a real sense of what we build, how we build it, and what your property could look like once we’re done. Each photo represents a real homeowner in Southern California who took the same step you’re thinking about right now.

60+ projects done

100+ of families helped

1:1 approach to your project

Unsure about choosing us? Request a quote to get to know us better! Let’s discuss your project. Or, call us at (562) 319-3178 now!

Straight From Homeowners Who’ve Been Through It

People ask us all the time how we know if a client is happy. The honest answer is they keep sending their neighbors our way. The reviews below come from real homeowners who went through the ADU process with Cornejo’s Builders from start to final inspection.

Marco Urbana

Rated 5 out of 5

Really good and professional company I love the fact that they are bilingual several companies came our to give a estimate but they were by far the most qualified and did a great job.

Uriel Castillo

Rated 5 out of 5

Cornejos has done multiple properties for me and never fails to deliver. Thank you!

What Does a Custom ADU Cost in Anaheim, CA?

ADU construction in Anaheim generally runs between $80,000 and $250,000, depending on scope, size, and the specific conditions of your property.

Those numbers come from past project estimates and are intended to provide a realistic reference point rather than a final answer. Your ADU project will have its own variables, and the only way to get an accurate price is to talk through your specifics with us.

Here are five factors that shape where your project lands within that range.

Size and square footage.
A compact 400-square-foot junior ADU has a fundamentally different cost profile than an 800-square-foot detached unit with a full kitchen, bathroom, and separate entrance. More square footage means more materials, more labor, and more permitting work.
Type of ADU.
Garage conversions often cost less because the foundation is already in place. Detached ADUs built from the ground up, above-garage units, and second-story additions involve more planning and structural work from the start.
Site and foundation conditions.
Every lot is different. Grading, soil stability, utilities access, and existing drainage all affect how much preparation happens before construction begins.
Finishes and design complexity.
Standard finishes and a straightforward layout keep costs lower. Custom design details, premium materials, and specialty fixtures raise the number, but they also raise the long-term value of the finished unit.
Permitting and city requirements.
Anaheim has its own permitting process, inspection schedule, and fees. We manage all of it on your behalf, but it belongs in any honest conversation about budget planning for your ADU project.

Your ADU, Built on Time and Within Budget

An investment in the $80,000 to $150,000 range sounds significant until you factor in what a permitted rental unit in Anaheim can actually generate each month. Many of our clients see their new ADU producing steady rental income within weeks of final inspection. Over time, that income can recover a large portion of your construction cost while the unit continues adding to your property value.

We run tight, milestone-based schedules because we know your home is not a construction site by choice. Our crew respects your space, keeps things clean throughout the build, and sticks to the agreed timeline in almost every case. When something comes up, you hear about it from us immediately, not after the fact. We value your home too much to leave you guessing.

How Cornejo’s Builds Your ADU, Step by Step

An ADU project can feel enormous on paper. In practice, it’s a series of clear steps, and we walk you through each one.

Collaborate

We listen first, then design around your needs and property.

Build

Our crew arrives on time and keeps you informed on the daily progress.

Enjoy

Move in knowing the work was done right the first time.

Common Questions About ADU Construction in Anaheim

How long does an ADU project take in Anaheim?

Most projects take between 4 and 9 months from permit approval to final inspection, depending on the size and complexity of the build. Garage conversions tend to move faster than detached ADUs built from the ground up. We give you a realistic timeline at the start and check in consistently throughout, so nothing ever comes as a surprise.

Do I need separate utilities for my ADU?

Generally, yes. Anaheim typically requires ADUs to have their own utility connections, and many homeowners also set up a separate address to keep rental arrangements simple. We coordinate with the city and utility providers as part of the construction process.

Can I rent out my ADU right away?

Once the final inspection is complete and your ADU is fully permitted, absolutely. Anaheim’s rental market makes that a genuinely worthwhile move for a lot of our clients. A well-built rental unit on your property can generate consistent monthly income while boosting the property’s long-term value.

What's the difference between a junior ADU and a detached ADU?

A junior ADU is built within the existing footprint of your home, often converting a garage or interior space, and is typically capped at 500 square feet. A detached ADU is a fully independent structure on your property with its own entrance, kitchen, and bathroom. Both are solid options, and the right fit depends on your property constraints, goals, and overall budget.

Put Your Anaheim Property to Work

Alexsander Cornejos

There’s a version of your property that includes a beautiful, fully finished ADU, a backyard guest house, a converted garage generating steady rental income, or a new living space built specifically for the people you care about.

Take a closer look at our custom ADU contractor services, and when you’re ready to talk specifics, call us at (562) 319-3178 or visit our contact page here.

The right team makes all the difference on a project like this. We’d like to be that team for you.

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Anaheim is Orange County’s most-visited city, anchored by Disneyland Resort and home to the Honda Center, one of Southern California’s busiest entertainment venues. The city’s updated ADU ordinances, established neighborhoods, and varied housing stock make it one of the more practical places in the region to invest in a custom ADU.