The aim of the thesis was to design and verified the reinforcement and cross-section of the part of flat slab, situated on the second floor of the twelve storey building. The slab have thickness 240 mm, made of concrete C30/37. I was analyzed slab D1 with dimensions 6,25x8,625m on punching resistance, The formwork drawing of the 2. floor and reinforcement of D1 slab were prepared.