Custom ADU Contractor in Garden Grove, CA

Garden Grove has always been a place where families put down roots, and a thoughtfully built ADU might just be the best thing you ever add to yours.

The Custom ADU Contractor Garden Grove Homeowners Keep Recommending

We started Cornejos Builders because we watched too many homeowners go through the same frustrating experience: a contractor who showed up with big talk, loose timelines, and then went quiet halfway through the job.

It happened to people we knew, and we decided the whole thing needed to be done differently. Over the past four years, we have built 24 ADUs across Southern California, and every single one of them taught us something.

We know how Orange County permitting works, how to read a lot for what it can actually support, and how to handle a garage conversion on a tight property without cutting corners. That kind of hands-on experience does not come from a brochure.

What keeps our clients coming back and sending their neighbors our way is that we stay in the conversation. From the first walkthrough to the final inspection, you always know where your project stands.

We treat every ADU build as if it belongs to someone we care about, because it does.

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 Have Actually Built in Garden Grove, CA

Every project in our portfolio has their own story: a family who needed more room, a homeowner who wanted rental income, or a couple making space for an aging parent. Take a look at our completed builds and get a feel for the quality and care we bring to every job.

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!

Garden Grove Homeowners Talk About Their ADU Experience

We could describe what it’s like to work with us, but the families who have been through the process say it far better than we can. Read through their experiences and get a real sense of what your own project might look like.

Mayra Ramirez

Rated 5 out of 5

Cornejos builders were great! I appreciate the thorough walkthroughs of the service and we loved the work you did for us.

Ronda Welker

Rated 5 out of 5

We couldn’t have asked for a better contractor to work with than Alex. We were needing our home remodeled in a very short window of time and Alex and his crew were always on schedule and in touch with us throughout the whole remodel. We would definitely use them again.

What Does a Custom ADU Cost in Garden Grove, CA?

ADUs in Garden Grove typically range from $80,000 to $250,000, depending on scope, size, and the specific needs of your property. That is a wide range, and there is a good reason for it.

No two lots are the same, no two families want the same thing, and no two projects come together identically. The best thing you can do is sit down with us, walk us through what you are thinking, and leave with a realistic number you can actually plan around.

Five things that will shape your final cost:

ADU Type and Size
A junior ADU within your existing home costs considerably less than a full detached ADU with its own foundation, utilities, and roofline. More square footage and more structural work mean a higher investment, and that’s just the reality of construction.
Site Conditions
Slope, soil quality, drainage, and the overall prep work your yard needs before building begins all affect the budget. Some lots are practically ready to go. Others require more groundwork before a single wall goes up.
Permits and Local Requirements
Garden Grove falls under California state ADU regulations and Orange County requirements. Handling permits correctly from the beginning saves money over time. Permit fees, inspections, and utility hookups all factor into the overall cost.
Finishes and Features
A simple, functional unit costs less than one with premium flooring, upgraded fixtures, or a custom kitchen layout. We help you decide which finishes make sense, whether that’s to maximize rental income or to build a beautiful space for family members.
Utilities and Connections
Separate electrical panels, new plumbing runs, and HVAC hookups for a new accessory dwelling unit add real scope. These are not optional, and factoring them in from the start keeps your budget honest.

Your Budget and Timeline, Protected

An ADU in Garden Grove might feel like a significant number at first glance. Spread that cost across the years you will spend using the space, though, and the picture changes. If your unit brings in $1,500 a month in rental income, it starts paying for itself. If it houses a parent or a grown child, it’s basically priceless.

We have been doing this long enough to know that delays hurt everyone. They cost money, disrupt daily life, and wear down trust. That is why we set realistic timelines at the start and hold to them. Our crew respects your home, keeps the site tidy, and communicates openly if anything unexpected comes up.

Your ADU, Handled From the First Sketch to the Final Walkthrough

Many homeowners expect the process to be complicated. With Cornejos Builders, the complexity stays on our side of the table.

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.

Questions Garden Grove Homeowners Ask About ADUs

How long does an ADU build take in Garden Grove?

Most ADU projects run between four and twelve months from design to final inspection, depending on the type of unit and how the permitting process unfolds. We give every client a realistic timeline at the start and check in consistently so nothing comes as a surprise.

Do I need permits to build an ADU in Garden Grove?

Yes, permits are required for any ADU construction in California. We handle all permit applications and coordinate with city requirements on your behalf, so that part of the process does not fall on you.

Can I build an ADU if my yard is on the smaller side?

Usually, yes. A garage conversion or an attached ADU works well on lots where a detached structure would not realistically fit. We assess every lot individually to tell you what is actually possible and what the best option looks like for your specific situation.

Will adding an ADU raise my property value?

In most cases, yes, particularly in Southern California, where housing demand stays strong and rental income from a separate unit adds measurable value at appraisal. A properly permitted, well-built ADU increases your home’s attractiveness to future buyers and puts real equity to work.

Give Your Garden Grove Property the Space It Has Always Had Potential For

Alexsander Cornejos

You’ve been sitting on untapped potential in your own yard, and every month that passes is a month you are not enjoying that space, not earning that rental income, or not giving your family the room they need.

Call us at (562) 319-3178 or send us a message, and we will set up a time to walk your property together.

If you want to learn more before reaching out, read about our custom ADU contractor services and see what a full-service build actually includes.

(takes 1-2 min)

Garden Grove CA is a well-established Orange County city with deep community roots and a character that has stood the test of time. Families come for the schools and the neighborhoods, and they stay because of the sense of place. The city is home to the beloved Strawberry Festival, one of the longest-running community traditions in California, and the remarkable Christ Cathedral, a landmark that draws visitors from across the region.