Timber roof truss
![Two King post trusses linked to support a roof.Key:1: ridge board, 2: purlins, 3: common rafters. This is an example of a](/Images/godic/202502/13/Roof_parts_simplified.svg2958.png")
![King post truss.Key: 1: King post, 2: tie beam, 3: principal rafters, 4: struts.](/Images/godic/202502/13/King_post_truss_3D.svg2958.png")
![Queen post truss.Key: 1: Queen posts, 2: tie beam, 3: straining beam, 4: principal rafters.](/Images/godic/202502/13/Queen_post_truss.svg2958.png")
![German illustration of a purlin roof with liegendem stuhl truss highlighted in blue.](/Images/godic/202502/13/Kehlbalkendach_mit_liegendem_Stuhl_1200px2958.png")
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.