Project Overview

The Bonsall Drive residence demonstrates how modular construction can support highly customized residential architecture. Developed in collaboration with Plant Prefab, the project uses factory-built modules combined with a specialized structural system that allows for open living spaces, expansive exterior openings, and integrated outdoor features.

The home was constructed using 11 modular units, which were fabricated off-site and assembled at the Malibu property. Architectural elements such as exterior decks and trellises extend the living space outdoors while complementing the home’s contemporary design.

ISE Structural Engineers provided structural engineering services for the project, developing a structural system capable of supporting both the architectural vision and the unique requirements of modular construction.

Project Type: Modular Custom Residential

Location: 5924 Bonsall Drive – Malibu, California

Services Provided: Design for a hybrid steel and wood structural system, including the lateral framing, mateline connections, and lifting-compatible elements to support the fabrication, transportation, and assembly of the modular units.

Structural Design Approach

The architectural design for the home emphasizes open interior spaces and large exterior openings. These features limit the use of conventional shear walls and required a structural system that could maintain lateral stability while preserving the open floor plan.

To support these design goals, ISE developed a steel frame lateral system integrated within the modular units. Steel rim beams and corner columns provide structural support while also serving as key lifting points during transportation and installation of the modules. Within this steel framework, wood infill framing and gravity framing were used to complete the structure while remaining compatible with the modular fabrication process.

This hybrid structural system allowed the design team to maintain the architectural openness of the residence while ensuring the structure could safely withstand transportation, lifting, and final assembly.

_{The open-concept floor plan features expansive interior spaces and large exterior openings, supported by a structural system designed to maintain stability while preserving architectural openness.}

Addressing Mateline Structural Requirements

Modular buildings introduce additional structural considerations at matelines, the boundaries where individual modules connect. Because the Bonsall Drive residence features an open-concept layout, maintaining structural continuity across these boundaries required careful engineering.

ISE addressed this challenge by incorporating steel mateline framing to reinforce the module interfaces while allowing the interior layout to remain open and flexible. The design also includes a stepped ordinary moment frame that spans across mateline boundaries, helping maintain lateral stability while accommodating the architectural layout.

This structural solution allowed the design team to support the architectural intent while ensuring the building performs as a unified structure once the modules are assembled.

_{Architectural and structural drawings showing the mateline connection details that reinforce module boundaries while maintaining the open-concept layout of the residence.}

Modular Engineering in Practice

Modular construction requires structural design to account for multiple phases of the building process, including factory fabrication, transportation, lifting, and final assembly. Each phase introduces different loading conditions and coordination requirements.

ISE’s experience with modular projects allowed the structural systems for the Bonsall Drive residence to be designed with these factors in mind. By integrating lifting-friendly steel framing elements, coordinating structural connections across modules, and accommodating the architectural layout, the engineering team helped ensure the project could be fabricated and assembled efficiently while maintaining structural integrity.

Project Outcome

The Bonsall Drive residence highlights the potential of modular construction for custom residential architecture. Through collaboration between the architect, Plant Prefab, and ISE Structural Engineers, the project demonstrates how modular systems can support complex architectural designs while maintaining the efficiency benefits of off-site construction.