Southern California ADU Builder, Garage Conversion & Backyard Home Construction
Create More Space, Flexibility, and Value With a Modern ADU
Accessory Dwelling Units (ADUs) have become one of the most desirable and valuable additions for Southern California homeowners. Whether you want space for family, a private suite for aging parents, a rental income unit, or a guest house in your backyard, Guthrie GC specializes in designing and building ADUs that meet your needs while complying with all San Diego and Riverside County ADU regulations.
From garage conversions and attached ADUs to full standalone backyard homes, we handle everything—site planning, architectural design, Title 24 energy compliance, CALGreen requirements, engineering, permitting, and turnkey construction. Every ADU is crafted with the same level of attention, quality, and customization as a full-size home, giving you a high-performance living space that enhances your lifestyle and adds significant value to your property.
Our ADU Construction Services
Backyard ADUs & Detached Units
Build a private, self-contained home perfect for guests, rental income, or multi-generational living—designed to maximize your lot and meet California ADU codes.
Garage Conversions
Transform your unused garage into a comfortable, fully compliant living space with structural reinforcement, insulation, plumbing, electrical upgrades, and luxury finishes.
Attached ADUs & Home Additions
Expand your existing footprint with a high-functioning suite connected to your home—ideal for extended family or flexible living arrangements.
Architectural Design & Engineering
Our ADU experts plan layouts, elevations, and full permit-ready drawings including structural engineering and Title 24 energy reports.
Turnkey Construction & Premium Finishes
From framing and roofing to cabinetry, fixtures, HVAC, and smart-home pre-wiring, your ADU is built with durable materials and modern California styling.
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"At Guthrie GC, we build homes with honesty, craftsmanship, and care. Every project is guided by real-life experience and a commitment to creating spaces that truly support the way you live."
Gordon Guthrie
President & CEO, Guthrie GC
Why Build an ADU With Guthrie GC
Building an ADU in Southern California requires a contractor who fully understands local regulations, lot restrictions, utility requirements, and zoning dynamics. At Guthrie GC, we guide you through the entire process—starting with site evaluation and feasibility, followed by detailed architectural plans and complete permit management with your city’s building department. Our team ensures your ADU meets all requirements for square footage, setbacks, height limits, parking exemptions, and energy compliance.
During construction, we deliver a smooth, transparent experience supported by experienced project managers, skilled trades, and premium materials selected for long-term durability. Whether your goal is to create rental income, increase property value, or provide a comfortable space for family, your ADU will be built with precision, code-compliance, and modern design that elevates your entire property.