The load-bearing system of a collar beam roof consists of two beams (= rafters) inclined against each other, which are hinged at the ridge point. The foot points must be freely rotatable for horizontal and vertical forces, but must be immovable. Compared to the rafter roof, the rafter pairs are connected with a horizontal transom. This allows for longer rafter lengths and thus higher roof areas. For wider buildings, the collar beam can also be supported by one or more supports. This is then referred to as a single, double or triple standing roof truss.
Source: bauwion
