Proposed Nutmeg Detached ADU

Project Details

This project involves the structural design and engineering of a new two-story detached Accessory Dwelling Unit (ADU). The structure is designed with a 404 sq. ft. one-car garage on the ground level and a 530 sq. ft. living space on the second floor, which includes one bedroom and one bathroom. The primary structure utilizes Type V-B wood-frame construction and is designed to be fully sprinklered for enhanced fire safety. The comprehensive structural scope required modern engineering solutions for the entire assembly, including a reinforced concrete foundation system with specific footing and baseplate details. The design process included detailed layouts for shear walls on both the ground and second floors to provide lateral load resistance, as well as specific schedules for floor joists, stair joists, and roof framing. All structural elements were engineered in strict accordance with the 2022 California Building Code (CBC) and the 2022 California Residential Code (CRC). The project also integrates sustainable and high-efficiency features, such as a solar PV system and water-conserving plumbing fixtures. Environmental compliance was a key design factor, with the structure meeting the requirements of the 2022 California Green Building Code regarding indoor water use, material conservation, and moisture control for building materials.

Role

Structural Engineer/Designer

Services Provided

The scope of services included the preparation of structural analysis, design calculations, and structural drawings for the proposed accessory dwelling unit (ADU) to be constructed above an existing garage. Structural analyses were performed for applicable wind, seismic, dead, and live loads in accordance with the governing building code and site-specific design criteria. The work involved the structural analysis and design of all structural elements associated with the new ADU, including the verification and strengthening of existing foundations and footings where required, as well as the design of columns, beams, floor framing, load-bearing walls, shear walls, roof framing, diaphragms, holdowns, connectors, and other supporting structural components. A structural evaluation of the existing garage framing, slab, walls, and foundation systems was also performed to verify their adequacy for supporting the additional ADU loads, with strengthening recommendations incorporated where necessary. The services further included the preparation of structural drawings consisting of foundation plans with retrofit and strengthening details, floor framing plans for the ADU level, roof framing plans, shear wall layout plans for both the garage and ADU levels, structural building sections in longitudinal and cross-sectional directions, and typical structural details, notes, and specifications. All documents were prepared to facilitate permitting, coordination, and accurate implementation during construction.