Single-nave halls with a steel structure are used in industrial construction and as storage, sports, public facilities, temporary buildings, etc. In terms of design, they consist of: main load-bearing systems, purlins and support systems for the wall casing and roofing. Individual elements of the hall structure can be made of hotrolled profiles or cold formed, thin-walled elements with slender walls. The load capacity of the roof structure of an industrial hall, unconstrained by roofing, was analysed in the paper. The rigidity of the roof structure in its plane was ensured by an appropriate roof bracing system. It was also assumed that the work of the roof structure in a perpendicular direction to the roof plane is to be similar to the behavior of a steel grate - cooperation between purlins and rigid tie rods was assumed, with vertical loads applied only to the purlins.