Panelized Residential Roof System. I: Structural Design

Abstract

Two roof panel designs for residential applications were developed to span from ridge to soffit without intermediate supports. The two designs, the truss core and the stiffened plate, incorporate both structural and insulation features such that a conditioned attic space can be achieved. The structural component of the truss-core and stiffened-plate panels is fabricated from steel webs laser welded to steel face sheets. The truss core includes an exterior (roof side) and interior (attic side) face sheet, whereas the stiffened plate includes only an interior face sheet. A separate polyurethane foam insulating layer is located on either the panel interior or exterior face. Structural performance requirements are developed from residential building codes for web failure, flexural capacity, and deflection. The structural analysis includes dead, live, and wind loads for all three U.S. climate zones. A model for panel performance was developed and validated through prototype panel tests. Truss-core and stiffened-plate panel designs were identified that satisfy the loading requirements for horizontal spans ranging from 3 to 8 m. Stiffened-plate panels are generally lighter weight than truss-core panels by 10–25%. However, only the truss-core panel satisfies the most extreme loading case for 8-m roof spans.