Proposed Elrod Residence ADU & Garage Addition

Project Details

This project entails the structural design and engineering for a multi-level Accessory Dwelling Unit (ADU) and garage addition for the Elrod Residence. The development includes a ground floor garage, a second-story ADU, and an accessible rooftop deck topped with a wood pergola. The structural framework is a hybrid assembly utilizing Douglas Fir Larch wood framing (joists, rafters, and beams) integrated with structural steel members, including A992 W-shapes and A500 Grade C HSS columns, to support the complex architectural layout. The foundation system is constructed with 3,000 psi reinforced concrete and features a combination of a 5″ thick slab-on-grade, a 10″ minimum thickness mat slab at the pool level, and independent wall and HFX footings. Engineering for the project follows the 2022 California Building Code (CBC), 2022 California Residential Code (CRC), and ASCE 7-16 standards. To provide lateral stability against environmental loads, the design employs 15/32″ structural plywood shear walls and high-performance Hardy Frame (HFX) panels, specifically engineered for Seismic Design Category D and wind speeds of 96 MPH (Exposure B). Additionally, the scope includes site-specific reinforced concrete retaining walls (RW-1, RW-2) and pool walls (RW-3) designed for a soil bearing capacity 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 project. Structural analysis considered wind, seismic, snow (where applicable), dead, and live loads in accordance with the governing building code and site-specific design criteria. The work included the structural analysis and design of all primary and secondary structural elements, including foundations, slab-on-grade, columns, beams, floor framing, roof framing, roof deck framing, wood pergola framing, stair framing, shear walls, diaphragms, holdowns, chords, and connectors. The services also included the structural design of the new swimming pool and hot tub shell, as well as the structural evaluation of the existing retaining wall and the design of a new full-width retaining wall system, either as a replacement or integrated with the existing wall, subject to site conditions and constructability requirements. Structural drawings were prepared to identify the framing systems, retaining wall, pool and hot tub structures, and all required structural details, sections, notes, and specifications to facilitate permit review, coordination, and construction.