Abstract: Prefabricated room structure for facilities in general, such as toilets, bathrooms, kitchens and the like, suitable for installation in a finished form into a building, in which there are prepared separately and in finished form: lateral walls floor and ceiling of the room structure. The so prefabricated finished wall, floor-and-ceiling component parts of the room structure are assembled together on the site by screw fastening and/or welding together the jointed formations to obtain the room structure in the form of a box-like member ready to be installed into the building as a unit.