The article presents and solves the problem of finding the design of minimum weight structural slab roof for given steel class, element cross-section type, and loading conditions. Structural roof slabs are widely used for large-span public and industrial buildings and allow a wide variety of structural and architectural forms. At the same time, the placement of supports was changed. In total, 10 options for the supports placement for the 36×36 m structural slab and 6 options for the topology were considered. After applying the load, structure’s strain-stress distribution was determined numerically, a cross-section was selected and its weight was calculated. Then, different options of support were compared in terms of structure weight. In fact, the article solved optimization problem by optimality criterion of metal intensity, restrictions in the form of overall dimensions, topology and strength conditions.