Orange County ADU

We are a Design-Build ADU Construction Company meaning that we will design and build your new ADU for the budget we agree on.

We include all the design plans, structural engineering, we submit to the city, pull all the permits, buid your new ADU, turn-key.

Keith Daigneault - The owner of Orange County Construction

What Makes Us a Professional ADU Contractor in O.C.?

Hello, my name is Keith Daigneault, the owner of Orange County Construction, an ADU company and we specialize in building ADUs along with JADUs, Garage Conversions & Room Additions.

When you contact us for a FREE ADU ESTIMATE, Keith will be the person to call you, then come visit your project to get all info needed for your new ADU project and finally send you a completely itemized, written estimate. When hiring an ADU company it’s important to make sure they have built several ADUs, and fully understand the permit process and state guidelines.

As an ADU Contractor in Orange County, CA., we approach every ADU whether attached or detached as a custom project. We will design your ADU and create the design plans and get the ADU permits for you. We-Do-It-All. Orange County Construction ADU Contractor has beautifully completed ADU projects all over North OC. We just finished two in Costa Mesa, one detached in the city of Orange, one attached ADU in Huntington Beach, and a few garage conversion JADUs in several areas.

We offer our affordable ADU services in Anaheim, Buena Park, Costa Mesa, Cypress, Fountain Valley, Fullerton, Garden Grove, Huntington Beach, Irvine, La Palma, Lake Forest, Los Alamitos, Midway City, Newport Beach, Orange, Santa Ana, Seal Beach, Stanton, Sunset Beach, Surfside, Tustin, Westminster, Yorba Linda, and Rossmoor, CA.

Visit our ADU Frequently Asked Questions page for lots of great info about AUDs.

Custom Built ADU in Orange County, CA.

Completed ADU build in Orange County, CA

This ADU was designed and built to accommodate a client’s daughter with special needs. My client did all the interior decoration and design of the ADU which is a free-standing, 700 sq ft ADU.

This backyard ADU has two bedrooms, a nice bathroom, a great room consisting of a living room, dining room table, kitchen and stackable laundry room.


As a trusted and local ADU Contractor in Orange County, we cater to building and remodeling homes for our clients. As an ADU Company, we start with your free estimate and offer you a guaranteed price in writing for your ADU. Once hired we start the ADU plans and follow with getting a permit from the City Building department for your new ADU.


Custom Built ADU in Orange County CA

Another Beautiful ADU Build by
Orange County Construction

Photo Examples of ADU Construction in Orange County, CA


We are an experienced Design/Build company that can offer accurate pricing up-front before spending money on plans.

We Love Building ADUs

We do the complete design and build for you using the best materials and sub-contractors in Orange County today!

Enjoy Your New ADU

We will finish your ADU project on time and on budget allowing you to enjoy it for many years while adding value to your home.

ADUs are also known as (Accessory Dwelling Unit, in-law units, granny flats, secondary units, backyard cottages, guest house, garage conversion, JADU, and more. An ADU is a smaller independent residential unit located on the same property, or lot, as an attached or detached stand-alone single-family home or garage conversion. It is an affordable, effective, and innovative option to add the much-needed housing in Orange County, CA.

With the lack of housing options in the city of Orange, CA., ADUs serve a great purpose. Suppose you’re a buyer looking for a large property or a homeowner with a spacious backyard. In that case, you can repurpose the extra space to develop a second, smaller legal residence on the property.

Most first-time and even veteran home-buyers in Huntington Beach, CA. are constantly asking their realtors the exact meaning of ADUs as the rules only changed recently. Typically, accessory dwelling units offer innovative homeowners an effective and affordable way of extending their primary residence with extra space right outside the backyard.

In addition, home-buyers are increasingly competing to buy properties with ADU housing to gain a source of passive income via short-term rentals. Both buyers and sellers need to have a solid understanding of constructing their ADUs. It’s for this reason that you should work with an experienced and licensed contractor in Garden Grove, CA. 


Accessory Dwelling Units
Construction Process

ADU Construction

ADU Construction

ADU Design Plans

ADU Design Plans


Photos Of Some Recent ADU Projects in OC


Get a Fast & Free Quote For Your ADU Project


ADUs & Garage Conversion Common Questions

Why are they called "ADUs?

ADU stands for “Accessory Dwelling Unit” and the JADU is a “Junior ADU”. The name ADU is the official name the State of California gave when they mandated that all cities must allow them to be built. It’s also another name for “grandma unit” or “guest house” and more.

-click here for all ADU rules

What is a Garage Conversion?

That is when you convert your two car garage to a small living space or a JADU. It will need to be at least a two car garage or larger.

-click here for all ADU rules

What does an ADU need to include?

Every ADU needs to have a minimum of a kitchen with a fridge, range (or cook-top), cabinets for storage, sink and a certain amount of countertop space for food preparations. It also requires a hood and fan with ducting to the outside for the kitchen. Then you also need a full bathroom (tub or shower or both) and a sleeping area of no less than 7′ x 7′.

-click here for all ADU rules

Will my city allow me to build an ADU?

The short answer is “YES”, as long as you adhere to both the state and city requirements. If you do, then the City cannot deny you a permit. This is where we can help you, we know the laws.

-click here for all ADU rules

Does my ADU need to be detached?

You can do either, attached or detached. If it’s attached to your home, you have to have a separate entrance for the ADU and no access from the house into the ADU. You can also convert your garage to an ADU.

-click here for all ADU rules

What is a JADU?

Basically a JADU is the same as an ADU but it’s limited to 500 square feet or less. Most of the time they are built in small backyards or as a garage conversion.

-click here for all ADU rules

Our ADU Services We’ve been designing and building operations in Anaheim for detached, ground up ADUs and garage conversions for different types of clients. Our skilled and experienced contractors ensure your project is designed and finished to perfection. We are your one-stop-shop and best bet when it comes to semi-custom, predesigned models. Besides, if you have an idea in mind, our experienced contractors will turn it into reality. We handle all the aspects and details of the process, including: Architectural Design Drawings We’ve been designing small but effective ADUs and homes for decades. Structural Engineering We work with the best structural, electrical, and civil engineers possible to ensure your ADU is safe and energy-efficient. Permit Processing Acquiring a permit for your ADU construction can be a daunting task that requires rigorous paperwork and inspection. Our secret weapon is that we’re the best with expeditiously permitting your ADU. Construction As one of the best construction companies in North OC, we bring the experts and proper tools to bring your ADU from concept to reality. Finish and Fixture Options We provide an array of finish options to customize your Los Alamitos ADU to and beyond your expectations. With vast experience in the industry, we ensure to keep your ADU appealing without being overwhelming. Financing Partnerships By working with us, you’ll get access to suitable local lenders that can offer you fantastic financing options on your ADU. FAQs
  • Can I hire any general contractor?
  • What should be in my ADU contract?
  • Is there a minimum lot size requirement?
  • Can I build an ADU in a historic district?
  • What is a statewide exemption ADU?
  • Can I be forced to have more parking?
  • Can setbacks be required for ADUs?
  • Is flexibility for siting parking required?
  • Is there a limit on the height of an ADU?
  • Can ADUs be exempt from parking?
  • Is there a limit on the number of bedrooms?
  • How do I find a good ADU contractor?
  • Can impact fees be charged for an ADU?
  • Can I convert my accessory structure into an ADU?
  • Can school districts charge impact fees?
  • Can converting existing space be expanded?
  • Can I still be charged water and sewer fees?
The Full ADU process from Plans to Finish Once you’ve signed a contract and your window to cancel has expired, our experts will visit your resident and take all the measurements for the construction plans. Below is the critical path that we follow:
  • Measure home, design project, and review with the owner
  • Once the design is accepted, we move on to the structural engineering and title24
  • When the plans are completed, we move on to the City for the plan check
  • Projects usually get kicked out 1-3 times for adjustments
  • Once the plans are approved, we pull permits and break ground.
How long will my ADU take to build? On average, ADUs run between 4-6 months from breaking ground. Although this may be a large spread, numerous factors are at play. These include the ADU’s size, detached or attached, a garage conversion, how busy the City is, how fast we can source materials, and more. Building an ADU in Huntington Beach can be one of the easiest cities in the county. Benefits of Adding an ADU to Your Property ADUs of one or two bedrooms with their bathroom and kitchen can be used in several ways. You can use them as a guest house for visiting guests and family members, home office space, or even an in-law’s new abode. In the past five years, the United States has seen a sharp increase in demand for affordable housing. This, in turn, saw an increase in ADU construction. Investors and homeowners are starting to realize the benefits of living on their property without additional utility bills and mortgage payments. Below are the top benefits of constructing an ADU on your property. Rental Unit to Generate Passive Income If you’re wondering whether an ADU in Costa Mesa is a good investment, the answer is a big YES! The main reason most innovative homeowners turn to accessory dwelling units is to bring a significant passive income. You can either generate short-term rental income or long-term reoccurring income. For instance, you can generate short-term income from the ADU if you reside in a vacation destination area. You can use services such as Airbnb to rent your Fullerton ADU for a weekend, weekend, or month at premium rates. This income can cover a large chunk of your monthly mortgage payment. Increased Property Value Another popular reason for adding an accessory dwelling unit is to raise the value of your property. You don’t have to break the bank to achieve this. Converting your garage or constructing an ADU will do just that. Most prospective homeowners and buyers are willing to pay more for Placentia properties with ADU extensions. They provide increased privacy, flexibility, and reduced monthly living expenses. Private Guest Accommodations When friends, guests, or family have visited for an extended period, having a separate private accommodation outside your main house offers privacy to both parties. A separate living space, bedroom, and kitchen for your guests will reduce disruptions in your daily schedule. For example, if you have elderly parents, in-laws, or grandparents, a separate ADU in Santa Ana will allow you to spend time together while maintaining your privacy and schedule. This is a more attractive option than putting them in a nursing home. Depending on your site plan, a Rossmoor ADU and main house are organized around a communal outdoor living space. This is a great way to spend evenings together outdoors and allow each party to retreat to their quarters for the night. Low-cost housing for adult children In many states where the living cost is exceptionally high, a detached ADU on your property in Westminster can be the ideal place for your adult children to reside while they’re studying or getting on their feet. ADUs provide a separate and private space for adult children to gain some independence and learn to save money. Yorba Linda ADUs can be the ideal stepping stone during the transition times of their lives. Separate working space You must have heard of giant companies that started out of the home garage. Likewise, if you have a home business, an ADU can help improve focus and productivity. You can use it as a workshop, office, or art studio to have a separate private space for client meetings. This creates a more professional setting than a home office in the primary residence. It also eliminates commuting as well as the wasted time in traffic. Besides, instead of injecting money into office rent every month, you can invest the money into constructing an ADU in Garden Grove. Depending on your resources, you can have separate parking and entrances to appeal to your business more professionally. Affordability ADUs in the city of Orange are affordable to construct since they don’t require major new infrastructure, paying for land, elevators, or structured parking. Besides, most ADUs are constructed with cost-effective materials, which are less costly than the homes in new multifamily infill constructions. Regardless of why you want to construct an ADU on your property, we’re always ready to turn your dream into reality and help you realize your benefits. Options for ADUs Most of the ADUs or multi-generational households are growing in popularity, with over 65 million people, or 20% of the American population living in an ADU. If you’re planning to follow this route, you might be wondering which option or type of ADU is the ideal choice for your property. Below are the most common types of ADUs in Buena Park: Detached ADUs: Completely separate units built aside from the primary residence Attached ADUs: Share a wall or two with the primary property but are newly built constructions Interior conversion ADUS/JADUS: Newly developed living units within the walls of the primary property. They typically don’t exceed over 500 square feet Exterior conversion ADUs: These are the garage conversions and include the basement and attic conversions. It’s essential to understand that not all ADUs are built equal. Every ADU type has its benefits and disadvantages. Finding an ADU Contractor requires some work in making sure they are very knowledgeable with the city requirements to pull an ADU permit. ADUs Vs. JADUs Generally, there are two main ADU types: the standard ADUs and Junior ADUs or JADUs and Garage Conversions. A standard ADU is developed by creating a new space separate from the primary property and detached or attached. A JADU can also be converting existing living space in your house without adding additional square footage onto your home, otherwise called an addition or room addition. On the other hand, JADUs include converting the current space within the primary residence into a new and separate living unit. The most common types of JADUs are garage conversions, although attic and basement conversions are also becoming popular options. Pros of standard ADUs
  • Renting them is easier
  • You can decorate the new space however you like
  • They don’t eat into the existing storage space such as parking space, garage, attic, or basement
  • They are not as disruptive as other types
  • Costly construction
  • Require specific permits
  • You must have space for them in the yard
JADU Pros Although some homeowners might view JADUs as a less desirable choice, they also have some benefits:
  • They’re cheaper to build
  • You capitalize on the existing space
  • They’re not private
  • Take away your garage or storage space
  • Interior ADUs do not offer extra space
Detached ADUs Detached ADUs are among the most popular in Anaheim, CA. They have numerous advantages that usually see most homeowners starting an ADU project. They’re entirely separate living units, don’t share a wall with the main residence, and have their entrances, utilities, and facilities. When people discuss granny flats and backyard cottages, they envision the detached ADUs. Pros
  • Offer the best privacy
  • Best choice to rent out
  • Keeps disruption to the minimum
The cons
  • Requires space
  • Requires more money
  • Require separate utility lines or update of the current ones
  • Requires special permits
Attached ADUs The attached ADUs are separate from the primary house regarding facilities and utilities. However, they do share a wall or two with the main residence. People opting for this option normally use them as living spaces for relatives, family, or extra office space. Pros
  • Offer the most privacy after detached ADUs
  • Not as expensive as detached ADUs
  • It can still be costly
  • Requires extra land to construct
Overall, if you have the money, space, a detached ADU is an excellent choice. However, constructing one will take effort, time, and money, which is why we are here! Since we’re intimately familiar and experienced with the advantages and drawbacks of all ADU types, we always work hard to ensure our clients get the ADU that best suits them. If you’re unsure of the direction to take on your ADU design, we can help. We offer full experience, and our team will also help with:
  • Minimization of construction noise
  • ADU renter help
  • Help with financing
  • Adding value to your home
  • Financing Partnerships
  • Permit Processing

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