ADU Contractor in South Gate, CA

Build the space your home’s been missing, with an ADU designed for the way you live.

Adding an ADU changes how your home works. It gives you room to adapt whether that means creating a private space for family, generating income through a rental, or simply using your lot more efficiently.

At Cornejos Builders, we’ve built over 20 ADUs right here in South Gate over the last four years. Detached units, garage conversions, second-story additions, we’ve worked on all types. We know the city’s requirements, we understand the approval process, and we’re used to working within tight property lines and even tighter timelines.

You’ll always know what’s happening, who’s doing the work, and when to expect the next phase. Our crew is respectful, highly skilled, and easy to have on-site, which matters more than most people expect.

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.

Here's What Sets Us Apart

Our exceptional service level and benefits have revolutionized the accessory dwelling unit industry, setting unprecedented standards for quality and satisfaction.

Discover the difference by seeing the benefits we offer:

See Our Work in South Gate, CA

We’ve completed ADUs across South Gate from garage conversions near Tweedy Boulevard to detached backyard units on quiet residential streets. If you want to see what quality craftsmanship looks like, take a scroll through our portfolio. Real homes, real families, real results.

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!

What People in South Gate, CA Say About Us

Our clients will tell you working with Cornejos Builders is refreshingly straightforward. We show up when we say we will, we finish what we start, and we leave your space better than we found it. Check out our reviews to hear directly from homeowners who trusted us with their ADU projects.

Andrei Hienadz

★★★★★ 5/5

I had a fantastic experience with Cornejos Builders! They exceeded my expectations in every way. From the initial consultation to the final walkthrough, their professionalism and craftsmanship shone through.

Mayra Ramirez

★★★★★ 5/5

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

How Much Does an ADU Cost in South Gate, CA?

It’s completely reasonable to want to understand what an ADU contractor will cost and honestly, you should. The truth is, the numbers can vary a lot. We’ve built compact garage conversions that were fairly straightforward, and we’ve built detached ADUs that required full utility upgrades, structural work, and custom finishes.

Same category of project, completely different price tags. Why the difference? A few key things tend to push the budget up or down:

Project	Included	Total Cost
Alhambra, CA (735 sq. ft.)	New foundation, plumbing, electrical, HVAC, Spanish style finishes, custom kitchen cabinets, separate utility connections	$250k
Whittier, CA (535 sq. ft.)	Central AC, open concept kitchen/living room, rental income property, custom finish bathroom tile, vinyl engineer flooring, level 5 drywall finish	$150k
Downey, CA (798 sq. ft.)	Vaulted ceilings, level 5 smooth finish, exterior stucco with smooth finish, customized electrical smart home finish, curbless walk-in shower, central AC	$200k

Factors Which Can Influence The Costs Of Accessory Dwelling Units In South Gate

Several factors can significantly impact the cost of building an accessory dwelling unit in South Gate. Understanding these variables can help you better anticipate your project’s budget.

Larger square footage means more materials, labor, and permitting. Compact studio units are generally more cost-effective than full two-bedroom builds.

Garage conversions are typically less expensive than detached new builds or second-story additions. Each type brings a different scope of work.

Custom tile work, high-end cabinetry, and premium fixtures can elevate the space but will also affect the total investment.

South Gate has its own permitting timelines, inspections, and code updates. We handle all of it but the city’s complexity can influence your project budget.

Converting a garage is often less expensive than building from scratch.

Establishing independent utilities for your ADU, like electricity and plumbing, can influence the total expense.

Budget-Friendly & On-Time Completion

Construction work affects your home, your routine, and your budget so we approach every project with a clear plan, steady communication, and respect for your time and space.

Budget

Spread out over a decade or more of daily use, an ADU becomes more than a one-time expense it’s a smart, lasting improvement to your home. It adds usable space, increases property value, and creates new options for how you live or earn.

On Time

We don’t make loose promises about timelines we build realistic schedules and stick to them. You’ll know what’s happening, when it’s happening, and who’s responsible. Our team keeps the site clean, organized, and moving forward until the job is complete.

Our ADU Construction Process

We’ve simplified the ADU construction process in South Gate so you don’t have to worry about a thing.

Collaborate

We walk your lot, talk through ideas, and handle permits.

Build

Our crew gets to work—on time, on task, and respectful.

Enjoy

Your space is ready. No clutter, no delays—just keys and comfort.

FAQs About ADU Contractor Services in South Gate, CA

Do I need permits for an ADU in South Gate?

Yes, permits are required, and South Gate has specific zoning and building regulations. We handle the entire permitting process for you from drawings to inspections so you don’t have to deal with city paperwork or guesswork.

What’s the difference between a garage conversion and a detached ADU?

A garage conversion transforms your existing garage into a living space. A detached ADU is a stand-alone structure, often built in the backyard. Each has pros and cons, and we can help you decide what works best for your space and goals.

How long does it take to build an ADU?

Most ADU projects take several months from permits to final walkthrough. Garage conversions are typically quicker than new construction. We’ll give you a detailed timeline before we start, and you’ll always know what to expect.

Can I rent out my ADU in South Gate?

In most cases, yes. South Gate allows ADUs to be rented out, but rules vary depending on your property’s zoning and whether the unit is attached or detached. We stay up to date with all local ordinances so you stay compliant.

Start Your South Gate ADU with a Team You Can Trust

Alexsander Cornejos

If you’re thinking about building an ADU construction, don’t wait. Space is limited, prices are rising, and South Gate’s permitting environment keeps evolving. Partnering with an experienced ADU contractor now means fewer delays, and the sooner that new living space starts working for you.

Call us at (562) 319-3178 or reach out through our contact form and let’s talk about what’s possible for your home.

(takes 1-2 min)

Located in the heart of southeast Los Angeles County, South Gate is known for its vibrant neighborhoods, family-friendly parks like South Gate Park, and access to major freeways. It’s part of the Gateway Cities region and a short drive from attractions like the Watts Towers and The Bicycle Hotel & Casino. Whether you’re planning for extended family or exploring rental income options, South Gate is an ideal place to build an ADU.