Blaine ADU

Project Details

This project involves the structural analysis and design of a detached one-bedroom Accessory Dwelling Unit (ADU) measuring approximately 32′-0″ x 14′-6″. The comprehensive scope includes loading analyses for environmental forces and the engineering of all cold-formed steel (CFS) elements, including roof joists, floor joists, load-bearing walls, and shear walls, all supported by a specifically designed reinforced concrete foundation. The primary structure utilizes high-strength G60 galvanized cold-formed steel framing. Members 16 gauge and thicker are specified with a minimum yield strength of 50 ksi, while members 18 gauge and thinner provide a minimum yield strength of 33 ksi. The design utilizes various CFS profiles, including C-shaped studs with flange return lips (S-sections) and track components (T-sections) following SSMA nomenclature. The structural elements were engineered in accordance with the 2025 California Building Code (CBC), 2025 California Residential Code (CRC), ASCE 7-22, IBC 2024, and AISI S100-16 (2020) provisions. Special attention was given to lateral load resistance, with the structure designed to withstand a basic wind speed of 92 MPH (Exposure Category B) and high seismic demands corresponding to Seismic Design Category E. The foundation system features 10-inch thick reinforced concrete stem walls and 18″x12″ wall footings designed to perform reliably under a gross soil bearing pressure of 1,500 psf.

Role

Structural Engineer/Designer

Services Provided

The scope of services included the preparation of structural analysis, design calculations, and structural plans for the proposed structure. Structural analysis considered wind, seismic, dead, and live loads in accordance with the governing building code and applicable design standards. The work involved the analysis and design of roof rafters and trusses, shear walls, load-bearing walls, and all required steel structural elements, including beams, joists, and columns. Services also included the design of steel connections, such as column baseplates and framing connectors, as well as the design of the foundation system to safely support all applied loads and provide a continuous load path. Structural drawings were prepared to illustrate the design and included foundation plans, roof framing plans, shear wall layout plans, steel framing elevations and sections, steel connection details, and typical structural details, notes, and specifications necessary for permitting, coordination, and construction.