Proposed Main House, ADU, and Shop Loft

Project Details

This project involves the structural analysis and engineering design for a multi-structure residential development consisting of a primary two-story residence, an Accessory Dwelling Unit (ADU), and a detached shop building featuring a second-floor loft. The comprehensive engineering scope required integrated solutions for a wood-framed structural assembly, utilizing Douglas Fir Larch (No. 1 and No. 2 grade) for primary rafters and joists. To support long spans and heavy point loads, the design incorporates high-performance engineered wood products, including Parallam PSL ridge beams and TJI joists. The structural design process followed a rigorous evaluation in accordance with the International Building Code (IBC 2021), the California Building Code, and ASCE 7-16 provisions. The structures were engineered to safely withstand environmental loads, specifically a design wind speed of 92 MPH (Exposure B) and high seismic activity associated with Seismic Design Category D. Lateral load resistance is managed through a calculated layout of wood structural panel shearwalls and a seismic-governed diaphragm system. These elements are secured using specialized Simpson Strong-Tie hardware, including HDU and MSTA series hold-down connections. The foundation system features reinforced concrete wall footings and independent pad footings, all designed to perform reliably under a gross soil bearing pressure of 2,000 psf on Site Class D stiff soil.

Role

Structural Engineer/Designer

Services Provided

The scope of services includes the preparation of comprehensive structural calculations and structural drawings for the two (2) proposed buildings. Structural calculations shall include complete loading analyses for wind, seismic, dead, and live loads, based on the project site conditions and applicable building codes. The work shall encompass the structural analysis and design of all primary and secondary structural components, including foundations, shear walls, columns, beams, floor joists, headers, rafters or trusses, and all required connectors. The design shall ensure a continuous and code-compliant load path capable of safely transferring gravity and lateral loads from the roof down to the foundation system.

The services shall also include the preparation of a complete set of structural drawings necessary for permitting, coordination, and construction. The drawing package shall include a Foundation Plan indicating the layout and sizing of footings and foundation elements; Second Floor Framing Plans showing the framing arrangement and member sizing; **Roof Framing Plans** identifying rafters, trusses, beams, and bracing components; and First and Second Floor Shear Wall Layout Plans defining the lateral force-resisting system. The structural documents will further include structural sections, as well as typical structural details, notes, and specifications** required to clearly communicate design intent, construction requirements, and compliance with applicable codes and engineering standards. All deliverables shall be prepared to facilitate efficient plan review and accurate field implementation.