Custom ADUs – Design, Permits & Construction
Licensed • Insured • Bonded • 15+ Years Experience • Design-Build Experts • Serving Southern California
Looking for a trusted ADU builder in Irvine, CA? Kol & Co. is a licensed, insured, and bonded design-build ADU contractor specializing in custom accessory dwelling units (ADUs), detached ADUs, attached ADUs, garage conversions, and junior ADUs (JADUs). From architectural design and engineering to permits and construction, we manage every step under one experienced team.
Whether you’re planning to create a rental property, build a private home for aging parents, add a guest house, or increase your home’s value, we design and build ADUs that are functional, beautiful, and built to last. Our streamlined design-build process keeps your project organized, minimizes delays, and gives you one dedicated team from concept to completion.
With more than 15 years of experience serving Irvine and Orange County homeowners, we understand local building requirements, neighborhood standards, and the level of craftsmanship expected in communities like Northwood, Woodbridge, Turtle Rock, Orchard Hills, Great Park, Quail Hill, Portola Springs, Stonegate, University Park, Woodbury, Cypress Village, and Westpark.
Contact us today to schedule your consultation, an estimate and discover how a thoughtfully designed ADU can enhance your home, lifestyle, and long-term investment.
Accessory dwelling units are rapidly becoming one of the most popular ways to:
With state and city support for ADU development and streamlined permitting in many California cities, now is one of the best times to build.
A detached ADU is a completely independent living space built separately from your main home. It’s one of the most popular choices for homeowners looking to maximize privacy and long-term value.
Our detached ADU services include:
Garage conversions are often one of the most cost-effective ways to create additional living space because the existing structure can typically be incorporated into the new design.
Our garage conversion services in Irvine include:
We’ll evaluate your existing garage and recommend the most practical design based on your property’s layout and the City’s ADU requirements.
An attached ADU shares at least one wall with the primary residence while maintaining its own private entrance and living space.
They’re commonly used for:
Every attached ADU is carefully designed to integrate with your home’s existing architecture while maintaining privacy and functionality.
JADUs are often built by converting an unused bedroom, office, or portion of the main residence into a self-contained living area.
Depending on your property and local regulations, a JADU may include:
We’ll help determine whether a JADU or a full ADU is the better investment for your property.
One of the first questions homeowners ask is, “How much does it cost to build an ADU in Irvine?” The answer depends on several factors, including the type of ADU, its size, site conditions, and the level of finishes you choose.
As a general guideline, most custom ADU projects in Irvine range from $200,000 to $500,000+, depending on the complexity of the project. While every project is different, a custom ADU typically takes about 12 months from initial planning to completion, including design, engineering, permitting, and construction.
Estimated ADU Cost in Irvine
ADU Type | Estimated Investment |
Garage Conversion ADU | Starting around $200,000 |
Attached ADU | Approximately $220,000–$350,000+ |
Detached ADU | Approximately $250,000–$500,000+ |
Luxury Custom ADU | Varies based on design, size, and finishes |
Every property is unique, so we provide a detailed, transparent estimate after evaluating your home, goals, and site conditions.
Several factors influence the overall investment, including:
Type of ADU (detached, attached, garage conversion, or JADU)
Square footage
Foundation requirements
Structural engineering
Utility connections
Kitchen and bathroom design
Interior finishes
Site accessibility
Grading and drainage
Permit and engineering requirements
Energy efficiency requirements
Custom features and upgrades
Our goal is to help you make informed decisions that maximize both your budget and your long-term return on investment.
Yes. In most cases, all new ADUs, attached ADUs, detached ADUs, garage conversions, and JADUs require permits before construction can begin.
Building an ADU involves much more than obtaining a building permit. Depending on your project, approvals may include structural, electrical, plumbing, mechanical, and energy compliance reviews.
Permits commonly required include:
Every property is different, and local regulations can influence what type of ADU can be built, where it can be located, and how it must be designed.
Before construction begins, we evaluate important factors such as:
Reviewing these details early helps avoid costly surprises later and allows us to design an ADU that works with both your property and local requirements.
We discuss your goals, budget, and timeline, then visit your property to assess the site and determine the best ADU solution.
We create a custom ADU design, floor plan, and layout that maximizes functionality while complementing your home's architecture.
Our team coordinates engineering, construction plans, permit approvals, and helps you select finishes, cabinetry, flooring, countertops, fixtures, and other materials.
Once permits are approved, we manage every phase of construction, including foundation, framing, electrical, plumbing, HVAC, interior finishes, inspections, and quality control.
We complete a detailed walkthrough with you to ensure every detail meets our quality standards before your new ADU is ready to enjoy.
We proudly serve homeowners throughout Irvine, including Woodbridge, Turtle Rock, Turtle Ridge, Quail Hill, Shady Canyon, Orchard Hills, Northwood, Great Park, University Park, Portola Springs, Cypress Village, Stonegate, Westpark, Woodbury, and the Irvine Spectrum area.
Whether you’re looking to build a detached ADU, garage conversion, attached ADU, or a fully customized accessory dwelling unit, Kol & Co. is here to help every step of the way.
From initial design and architectural planning to permits, engineering, construction, and final inspections, we provide a seamless design-build experience focused on quality, transparency, and lasting value.
Let’s discuss your ideas, evaluate your property, and create a custom ADU designed around your lifestyle, budget, and long-term goals. Contact Kol & Co. today to schedule your consultation and receive a free transparent estimate for your Irvine ADU project.
Most ADU projects in Irvine require a building permit and plan review before construction begins. Depending on the scope, your ADU may also require structural, electrical, plumbing, mechanical, Title 24 energy compliance, utility, grading, and inspection approvals. Kol & Co. coordinates the plans, permit submission, city comments, revisions, and final inspections so your ADU is built correctly and code-compliant.
While every project is different, a custom ADU typically takes about 12 months from initial planning to completion, including design, engineering, permitting, and construction.
It depends on zoning and lot size, but many Irvine properties can accommodate a garage conversion or JADU even with limited space.
For many homeowners, an ADU is one of the best long-term investments they can make. In addition to increasing usable living space, an ADU can generate rental income, accommodate family members, improve property value, and provide flexibility as your needs change over time.
Depending on your property, local regulations, and project design, a two-story ADU may be possible. During your consultation, we’ll evaluate your lot and discuss the options available for your property.
Not always. Some ADUs share utility connections with the main residence, while others have separate services. The best approach depends on your property’s existing infrastructure and how the ADU will be used.
The ideal size depends on how you plan to use the space. During the planning process, we’ll help determine the most functional layout while making the best use of your property and investment.
