A prefabricated module has a lateral side to be connected to a plurality of panels and slabs for forming a part of a building. The module includes four walls extending between a floor and a roof to form a rectangular cuboid shape; interior equipment, at least some of which are connected to technical installations arranged within the cuboid shape; and a compartment within the cuboid shape which is provided with waterproof layers on the interior walls and floor for creating a wet area within the module.