Accessory Dwelling Units In Whittier, CA

Enhance your property with a stunning and durable new living space using our professional accessory dwelling unit construction services in Whittier, CA.

the interior of a new accessory dwelling unit california

Capitalize on a seamless ADU construction experience with us, the preferred choice in Whittier, CA. Avoid the disruptions and uncertainties of amateur workmanship. Instead, gain a professionally built, value-boosting, and regulation-compliant extension to your home.

Choosing our expert services means no second-guessing on quality. Homeowners in Whittier, CA enjoy flawless execution and superior finishes. Dodge the costly pitfalls of DIY attempts, and relish in the peace of mind that our professional guarantee provides.

new accessory dwelling unit built by Cornejos Builders
Alexsander Cornejo owner of Cornejo Builders California

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.

Benefits That Make A Difference

Our unmatched ADU construction services have revolutionized industry standards through uncompromising quality and tangible benefits. Witness how we redefine excellence—check out the benefits we offer:

With us, you’re getting:

Your Accessory Dwelling Units Project Could Turn Out As Great As These

Your ADU transformation could mirror the excellence showcased in our gallery below. Let these past successes inspire your project’s vision. For quality you can trust, peruse our gallery to grasp the standard of our work:
get a sense of the level of quality of our services:

60+ projects done

100+ of families helped

1:1 approach to your project

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Alexsander Cornejo owner of Cornejo Builders California

If you’re unsure about choosing us as your best option, why not request a pricing quote? Let’s have a discussion about your project so you can get to know exactly who you’ll be working with. Alternatively, feel free to give us a call at (562) 319-3178 to get in touch with us right away!

What Your Neighbors In Whittier Think About Us

Our customers’ testimonials reflect their satisfaction with our services. We have been in the industry for so many years now, that it would have been impossible for us to thrive as a business without offering great services. We’re profoundly grateful for their feedback. Check out the beautiful things people have to say about us:

Lanny Lam


Cornejo’s Builders did an amazing job remodeling our kitchen. Alexsander made this experience one of a kind, he was accessible and flexible throughout the process. 

This guy’s knowledge truly guided us to perfect our dream kitchen. He has endless recommendations. The workers were efficient. We appreciate how he handled minor changes we had with professionalism. 

After getting work done by different General Contractors, Cornejo’s Builders definitely sets the bar for the rest. Thank you, Alexsander.


Lety Ortega


Called Cornejo’s Builders after seeing their beautiful work on Tik Tok. Spoke to the owner regarding an ADU project. Alex always returned my calls, explained throughly how the project would be completed. 

Love how his company is an all in one stop. They definitely handle everything from getting permits, architect, plumbing, electrical etc. Turn key ready, his prices are very reasonable and is willing to work around your budget

Alex was very understanding when I explained why I had to put a hold on the the project. He definitely treats his customers like family.

Accessory Dwelling Units Costs In Whittier

ADUs range from $80,000 to $250,000, depending on the scope of work and size. Instead of estimating costs, it’s wise to request a free quote, consult, and determine a realistic price for your upgrade.

Investing in an ADU is a wise decision, but costs vary widely because no two projects are the same. A tailored quote that reflects your exact needs is achievable once we discuss the specifics of your project. Contact us for a detailed and personalized estimate.

ADU Size Features Included Cost Estimate
New 735 sq. ft. Two-Story ADU (Alhambra, CA) New foundation, plumbing, electrical, HVAC, Spanish style finishes, custom kitchen cabinets, separate utility connections. Quoted at $250,000, with architectural plans at $15,000. $250,000
New 535 sq. ft. ADU (Whittier, CA) Central AC, open concept kitchen/living room, rental income property, custom finish bathroom tile, vinyl engineered flooring. Quoted at $150,000, with custom kitchen cabinets at $12,550. $150,000
New 798 sq. ft. ADU (Downey, CA) Vaulted ceilings, level 5 smooth finish, smooth exterior stucco finish, customized electrical smart home features, curbless walk-in shower, central AC. Quoted at $200,000, with bathroom tile at $8,000. $200,000

Factors Which Can Influence The Costs Of Accessory Dwelling Units In Whittier

Numerous factors come into play when determining the unique costing of your ADU project. It’s important to consider each one carefully.

Your design choices directly impact costs. Custom layouts and unique features require more resources.

The square footage of your unit significantly dictates material quantity and overall expense.

Opt for standard materials for savings, or premium ones for enhanced durability and aesthetics.

Local regulations and the fees for securing permits can vary, affecting your budget.

The condition of your build site may necessitate additional groundwork, influencing the cost.

Costs escalate with the complexity of integrating electricity, water, and sewer lines.

Engaging an architect can ensure compliance and design integrity, but adds to your investment.

Fast-tracked projects can increase labor hours, whereas extended timelines may add indirect costs.

Each of these factors plays a crucial role in crafting a personalized estimate for your ADU, ensuring transparency and alignment with your expectations.

We Respect Your Time & Budget

At our company, precision is paramount. We deliver accurate timelines and budget estimates, reflecting our professionalism in every project.

We respect the budget we initially discuss with you. Trust is foundational to our services, so we prioritize transparency from the start. By sticking to agreed-upon figures, we avoid surprises and ensure your financial comfort throughout the construction process.

Finishing your ADU on or ahead of schedule is a commitment we take seriously. Efficiency is key in our operations, and we leverage our expertise to ensure that your project is completed promptly, respecting both your time and expectation.

Simple 3-Step Process For Successful Accessory Dwelling Units Projects

Embarking on an ADU project with us means experiencing ease and clarity at every stage. We’ve distilled the process to three fundamental steps, ensuring that your role is uncomplicated and enjoyable. Put your trust in our expertise, and we’ll manage the complexities, allowing you to watch your vision come to life with minimal stress.



Engage with experts to tailor your design, ensuring practicality meets your personal touch.



Witness skilled artisans transform plans into reality with precision and care.



Revel in the comfort of your new ADU, delivered on time and within budget.

FAQs About Accessory Dwelling Units In Whittier

Typically, most ADUs can be constructed within a 90-day timeframe. Yet, keep in mind that the duration may vary based on project scope, complexity, materials, and features chosen. For an accurate timeline, we will provide you with specifics following our on-site assessment.

All individuals setting foot on your property are trusted, local tradesmen. We exclusively collaborate with top industry professionals, experts dedicated to your best interests.

Buying materials voids warranty. If we provide materials & install, you get warranty lasting 1 year to a lifetime.

Sure thing! You can preview a 3D design of your new ADU before finalizing any materials or design, ensuring you’re completely satisfied with your upgrade. Our design-build process includes these 3D renderings to make your experience smoother.

Absolutely! You’ll receive a 1-year warranty on every new ADU we build, along with a materials warranty on everything we purchase and use. Plus, count on our ongoing support – your needs will always take precedence.

A new ADU in Southern California features a kitchen, bathroom, living room, washer/dryer hookups, 1 bedroom or studio (size-dependent), central heating, water, gas, and electrical setups. We handle it all, providing you with a ready-to-use ADU on the day of completion!

ADUs range from $80,000 to $250,000, depending on the scope of work and size. Instead of estimating costs, it’s recommended to request a free quote, consult, and determine a realistic price for your upgrade.

All ADUs in Southern California must have a permit. But fret not! Cornejo’s Builders Inc. takes care of planning, permitting, and construction, so you can sit back, relax, and witness your dream home materialize.

Ready to Transform Your Home?

Building an ADU is more than just extra square footage; it’s a smart financial decision maximizing property value early on. Don’t delay—invest in your home’s potential now and see substantial returns in the future.

Alexsander Cornejo owner of Cornejo Builders California

Alexsander Cornejos

Reach out to us at (562) 319-3178 and let Cornejo’s Builders Inc. navigate the intricacies of your home expansion with precision. Securing your investment is just one call away.

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Andrei Hienadz​

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.

Julie Bean​


Amazing experience with Cornejos builders. From beginning to end- communication was clear as well as expectations. Work was 5 star and every member of the crew was exceptional

I would highly recommend Cornejos builders for ANY project or build. I will continue to use them and refer them for as along as they are available. 

Thank you for your beautiful work at such a competitive price!!!!

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Whittier, CA is a charming city with a rich historical tapestry and inviting green spaces. Key landmarks include the iconic Whittier College, with its strong educational presence, and the beautiful Pio Pico State Historic Park, celebrating the life of California’s last Mexican governor. This idyllic community weaves together cultural heritage and modern living, making it a hidden gem in the heart of Southern California.