what is a truss roof
This is an example of a double roof with principal rafters and common rafters. A timber roof truss is a structural framework of timbers designed to bridge the space above a room and to provide support for a roof.Trusses usually occur at regular intervals, linked by longitudinal timbers such as purlins. The space between each truss is known as a bay.losed truss: 1) A truss with a tie beam; 2) a roof system with a ceiling so the framing is not visible. Open truss: 1) A truss with an interrupted tie beam or scissor truss which allow a vaulted ceiling area; 2) Roof framing open to view, not hidden by a ceiling.