Modular ADU Installation in Huntington Beach, CA


Transform your property with seamless modular ADU installation from Refined ADU Builder & Garage Conversions, Huntington Beach's premier accessory dwelling unit specialists. Our expert team brings precision engineering and construction excellence to every project, ensuring your modular ADU installation exceeds expectations while maximizing your investment.


Modular ADUs represent the future of flexible living spaces—offering dramatic time savings, reduced on-site disruption, and exceptional quality control compared to traditional construction methods. Our comprehensive installation service manages every aspect from site preparation and foundation work to final utility connections and inspections.


Modular ADUs deliver remarkable value with their 3-5 month completion timeline—up to 60% faster than conventional builds. Every unit we install meets or exceeds California's stringent building codes and Title 24 energy efficiency requirements.


We understand that aesthetic integration matters. That's why we offer extensive customization options to ensure your modular ADU harmonizes perfectly with your existing home. From exterior finishes and roofing materials to interior fixtures and layout configurations, we help create a cohesive property appearance.


Our streamlined process guides you through design selection, permitting, site preparation, and installation with transparent communication at every stage. Experience the perfect balance of efficiency, quality, and personalized service with Huntington Beach's modular ADU installation experts.

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Our Modular ADU Installation Process

We guide clients through a structured process ensuring each modular ADU fits the site, meets design preferences, and complies with local standards. Our approach integrates assessment, custom design, efficient off-site building, and precise on-site installation.

01 Site Assessment and Preparation

We start by evaluating the property in Huntington Beach to determine feasibility for a modular ADU. This includes checking zoning regulations, setbacks, and utility access. We also assess soil conditions and site topography to plan foundation requirements.



Our team coordinates with local authorities to secure necessary permits and inspections in advance. Preparing the site involves clearing, grading, and installing foundational supports tailored to the modular design. This groundwork sets a solid base for a smooth installation process.

02  Custom Design

We work closely with customers to develop ADU designs that reflect their needs and the site constraints. This design phase includes floor plans, exterior finishes, and energy-efficient systems to match Huntington Beach’s climate.


Using 3D modeling, we present detailed visuals for approval. We integrate structural and mechanical elements early to avoid delays. Final plans comply with all California building codes, ensuring safety and quality. This step balances aesthetics with function and regulation.

03 Efficient Modular Construction

Our modular units are built in controlled factory settings to maintain consistent quality. Building off-site protects materials from weather delay and reduces waste. This method speeds up construction without compromising structural integrity.



We monitor progress with standardized quality checks at every stage. Prefabricated modules include plumbing, electrical wiring, and insulation, prepared to code before arriving on site. Modular construction enhances precision and decreases on-site labor needs.

04 Professional Installation

Once modules arrive, we handle delivery and crane placement with precision, ensuring proper alignment on the foundation. Our installers secure connections for utilities, finish exterior details, and manage on-site assembly.


We conduct thorough inspections to confirm compliance and function. Final approvals come from local inspectors to validate the installation meets all regulatory requirements. Our team remains on site until the ADU is ready for occupancy, guaranteeing a seamless handover.

Our Modular ADU Solutions

We provide a range of modular ADU options tailored to fit various property layouts and homeowner needs. Each solution focuses on efficient use of space, compliance with local regulations, and quality craftsmanship.

Detached ADU Options

Our detached ADUs offer complete privacy and independence from the main house. These stand-alone units come in customizable floor plans, including one- to two-bedroom layouts, designed to maximize comfort on lots of different sizes.



We manage all aspects from site preparation to final installation. Our detached ADUs include modern kitchens, bathrooms, and energy-efficient features. They are ideal for guest houses, rental units, or multigenerational living.

Attached ADU Designs

Attached ADUs connect directly to the primary home while maintaining a separate entrance. We tailor these designs to blend seamlessly with your existing architecture and neighborhood guidelines.



These units optimize available space that might otherwise be unused, such as basements or side extensions. We ensure functional layouts with ample natural light and accessibility upgrades where needed.

Garage Conversion

Transforming an existing garage into an ADU is a cost-effective way to expand living space without new construction. We handle electrical, plumbing, insulation, and layout redesign to meet ADU standards.


Our conversions create fully compliant living quarters suitable for family use or rental. We address permit acquisition and ensure structural integrity, preserving the overall value of your property.

Why Choose Us

We focus on local expertise, reliable craftsmanship, and clear communication at every step. Our goal is to provide seamless modular ADU installations tailored to Huntington Beach requirements.

Proven Expertise

We have extensive experience installing modular ADUs specifically in Huntington Beach. Our team understands local zoning laws, building codes, and permit processes, which helps avoid costly delays. Our portfolio includes a wide range of ADU types, from small backyard units to larger, more complex structures. We optimize designs for climate, site conditions, and neighborhood aesthetics, ensuring compliance and functionality.

Quality Craftsmanship

Quality is central to every modular ADU we install. We use durable materials designed for long-term performance and energy efficiency in coastal Southern California climates. Our skilled craftsmen follow strict construction standards and industry best practices. Each module is assembled with precision off-site, reducing on-site errors and ensuring better overall build quality.

Transparent Communication

We maintain open communication from project start to finish. Our team provides clear timelines, cost estimates, and progress updates regularly. Clients have direct access to our project managers who answer questions promptly and explain each stage in understandable terms. We believe transparency builds trust and helps clients make informed decisions.

FAQS on Modular ADU Installation

We provide detailed information about the specific modular ADU options we install. Our focus is on the types of units that meet varied needs and property conditions in Huntington Beach.

  • How much does modular ADU installation cost in Huntington Beach?

    Modular ADU installation in Huntington Beach typically costs between $200-$300 per square foot, with total costs ranging from $120,000 to $200,000 depending on size and customization. This includes foundation, delivery, installation, utility connections, and standard finishes. Permit fees and site preparation may add $10,000-20,000 to the total cost.

  • What are the time savings of modular vs. traditional ADU construction?

    Modular ADUs offer 40-60% faster completion times compared to traditional construction. While conventional ADU projects often take 9-12 months, modular ADUs can be completed in just 3-5 months total. The factory manufacturing process happens concurrently with site preparation, significantly reducing overall timeline.

  • Do modular ADUs meet California building codes and regulations?

    Yes, modular ADUs in California must meet or exceed all state building codes and regulations. They're built to comply with California Residential Code, Title 24 energy efficiency standards, and local Huntington Beach zoning requirements. Each unit receives state factory certification and must pass local inspections after installation.


  • Can modular ADUs be customized to match my existing home in Huntington Beach?

    Modular ADUs offer significant customization options including exterior finishes, roofing materials, window styles, and color schemes to complement your existing home. While not as infinitely customizable as stick-built construction, modern modular units provide numerous design options to ensure aesthetic harmony with your primary residence.


  • How long does modular ADU installation take from start to finish?

    The entire modular ADU process typically takes 3-5 months from signing to occupancy. This includes: 2-3 weeks for design finalization, 6-8 weeks for permitting, 6-8 weeks for factory construction, 1-2 weeks for site preparation, 1-2 days for installation, and 2-3 weeks for utility connections and final inspections.