Three part trusses are usually carried out as a truss made with rafters of straight glulam elements and ceiling joists of either glulam or steel. They are used for spans where trusses made of ordinary timber are not enough. A frame with a three part truss gives free spans and full freedom in the disposition of interior and inside constructions. This flexibility can be very valuable if the function of the building would change later on. The assembly requires mobile crane. Common roof angel is 14-30 degrees. A suitable building width is about 15-30 meters.