Pre-stressed mounting “TT” floor slabs are used both as roof and inter-oor structure. They are supported by RC mounting beams ( “L” and “T” cross section). “TT” slabs are made of pre-stressed concrete in a smooth steel formwork. They are produced in two different heights: h=35cm, and h=55cm. During assembly, after placement into intended position, a concrete topping of minimum 5cm thickness is required.