The roof (with a de-watering groove) and façade trapezoid sheet, which has a unique pattern (similar to T-18 Economic) and additional ribs. It improves the stiffness of the structure and provides an elegant appearance, with a touch of austerity. It is often used in the designing of petrol stations and as a covering of silos, heating boilers, as well as on ceilings and formwork filled with concrete.