ADU & Room Additions in Orange County
Expand Your Space. Increase Your Value. Build with RIA Group
At RIA Group, we help homeowners make the most of their property through custom ADU (Accessory Dwelling Unit) and room addition construction. Whether you’re building a backyard guest house, adding a new bedroom, or expanding your living space, we deliver a seamless design-build process that adds comfort, function, and long-term value to your home.
With over 20 years of residential construction experience, our team brings expert craftsmanship, code-compliant design, and transparent communication to every project across Orange County.
Build your ADU or Room Addition Today
Custom ADUs — Built Around Your Property & Lifestyle
Your Vision, Our Expertise
Every property is unique, and every homeowner has a vision. We design and build fully customized ADUs from detached backyard units and garage conversions to above-garage suites and multi-room guest houses.
Whether you’re creating a private rental unit, a family guest space, or a home office, our team manages everything from concept to completion zoning, design, permits, and construction.
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RIA Group handles the full scope of ADU development:
Site planning & zoning analysis
Custom architectural design
City permits & engineering approvals
Construction & utility integration
Final inspections & handoff
We ensure your ADU is not only beautiful but fully compliant with California’s ADU laws and Orange County building codes.
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Room additions require balance — the new space must feel like it’s always been part of your home. Our team designs additions that blend seamlessly with your existing layout, structure, and style.
Popular additions include:
Primary suite expansions
Second-story additions
Family rooms & great rooms
Home offices & studios
Kitchen & dining expansions
From framing to finishes, we ensure your new space feels cohesive, functional, and perfectly integrated.
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We integrate U.S.-built MeterHome™ battery energy systems for homes that are as sustainable as they are beautiful. With advanced backup power and energy management, you’ll enjoy comfort, savings, and security year-round.
Why Homeowners choose RIA Group
ADUs & Room Addition Builds in Orange County
Fully custom ADU & addition design-builds
20+ years of experience in residential construction
Licensed, bonded, and insured in California
Transparent, honest communication, and on time delivery
Proudly serving Orange County and surrounding areas
Commitment to craftsmanship, precision, and customer satisfaction
Integration-ready for solar & MeterHome™ systems
Service Areas
We proudly construct/build ADUs & Room Additions throughout:
Irvine, Newport Beach, Costa Mesa, Huntington Beach, Mission Viejo, Laguna Niguel, Tustin, Lake Forest, Aliso Viejo, Anaheim Hills, and neighboring communities across Orange County.
RIA Group builds high-quality ADUs and room additions across Orange County and nearby communities. With over 20 years of residential construction experience, our licensed team brings craftsmanship, innovation, and precision to every project. Whether you’re adding a new living space, building a backyard guest home, or creating a rental-ready ADU, RIA Group delivers results that enhance your home’s value, comfort, and design seamlessly integrated and built to last.
Expand Your Home With Confidence
From backyard ADUs to large-scale home expansions, RIA Group delivers projects that add comfort, functionality, and long-term value all while maintaining your home’s character and charm.
Our Process
Built on Experience. Honest Communication. Results That Last.
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Every project begins with you. We listen closely to your goals, ideas, and inspiration. Whether you’re remodeling a kitchen or building a custom home, we take time to understand your lifestyle, budget, and timeline so we can bring your vision to life.
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Our team visits your property to take detailed measurements, assess existing conditions, and discuss design opportunities. This helps us create realistic plans and identify potential improvements before work begins.
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This is where creativity meets precision. We develop a detailed plan that includes layout, materials, finishes, and structural considerations. Whether it’s custom cabinetry, countertops, or full-scale additions, every element is planned around your needs.
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We provide a clear, itemized estimate and timeline no surprises, no hidden costs. Once approved, we finalize your schedule and prepare permits if needed.
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This is where creativity meets precision. We develop a detailed plan that includes layout, materials, finishes, and structural considerations. Whether it’s custom cabinetry, countertops, or full-scale additions, every element is planned around your needs.
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Our experienced crew brings your design to life with precision and care. You’ll receive consistent updates, progress photos, and timeline checkpoints. We’re committed to staying on schedule and maintaining open communication at every stage.
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Before project handoff, we review every detail with you ensuring the finished product exceeds expectations. We only consider a project complete when you’re 100% satisfied.
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Your vision is now a reality. Our team performs a detailed walkthrough to ensure every element meets our quality standards and your expectations.