ZFA provided structural engineering services for a single-story, 20,300-square-foot addition to The Father’s House in Vacaville. The project included a new 500-seat auditorium, an expanded lobby, and additional classrooms to support the growing needs of the church.
The auditorium is constructed with a combination of structural steel framing and light-gauge cold-formed steel (CFS) bearing walls supported on a concrete slab floor and shallow concrete foundations. To save construction costs, ZFA utilized lightweight CFS wherever possible in lieu of heavy structural steel. The lateral force resisting system consists of both plywood sheathed CFS shear walls and concentric steel braced frames tied together with strategically placed collectors and a bare metal deck diaphragm. The roof is framed with open-wood steel joists and girders, which were incorporated in early stages of design to begin critical manufacturer coordination to ensure effectiveness and feasibility.
The roof includes six different metal deck elevations, with the auditorium roof approximately six feet higher than the adjacent lower building roof over the lobby, classrooms, and café. The varying roof elevations, along with the mix of structural steel and CFS gravity and lateral systems created structural challenges, particularly at vertical and horizontal collector connections between the separate roof diaphragms. ZFA thoughtfully coordinated details with the contractor in order to optimize construction sequencing between the CFS and structural steel trades.
Important elements of the project included the support of audio-visual (AV) and lighting systems in the auditorium and above the stage area, and the unique seismic bracing method of the hanging speakers. At the client’s request, ZFA provided custom detailing for a well-hidden bracing system, which involved extensive coordination and collaboration with the AV consultant and the open-web joist manufacturer. This effort resulted in a nearly invisible (yet cost effective and safe) bracing design.