upper restraining cables and over the tops of the vertically aligned compression struts and securing it to the opposite side of edge ring 6 and the struts when this is completed for all upper carrying cables 4 the structure is ready for prestressing the cables are prestressed in a selected sequence using techniques similar to those used for prestressing cable domes of the types discussed in the prior art referred to in the background section of this specification prestressing is achieved by extension of the struts 5 by tensioning of cables using anchors 9b or by a combination of these methods the prestressing is carried out to load edge ring 6 primarily in compression and to distribute the loads substantially uniformly throughout the cable nets as well as to achieve the desired cable curvatures fabric or other roof material strips are then secured to the upper carrying cables for example as illustrated in fig2 and 3 the edges of roof fabric runs 7 abutting edge ring 6 are secured thereto by upper and lower strips 10 illustrated in fig4 the lower strip 10 is affixed to edge ring 6 and is coextensive therewith and the upper strip 10 is superimposed thereon and fastened thereto the roof fabric edge is between the two strips 10 the structure can be provided.