Construction method of large span building roof or floor of building and its double lattice beam structure

A method for constructing the roof of large-span building includes such steps as in-situ casting the lower ribbed beams and shear keys in large lattice mode, putting the ribbed ferroconcrete slabs onthe shear keys to form rib slots between said slabs and lower ribbed beams, binding reinforcing bars in the rib slots, in-situ casting concrete, and curing. Its advantages are low cost, beautiful lattice pattern, and less possesses building space.