Abstract: A room-bounding structure (e.g., walls, floor and/or ceilings), in accord with an embodiment of the invention, includes a rigid sheet impermeable to moisture; spacer protrusions on the first surface of the sheet at essentially even intervals over the entire area of the sheet; and a rigid surface sheet supported on the spacer protrusions, in such a way that the space between the sheet and the surface sheet forms a network of air channels for ventilating the structure. In another embodiment of the invention, a structural system for a room-bounding structure includes a casted structure, and a perforated conduit with an inlet and outlet outside the casted structure, at least a portion of the conduit embedded in the casted structure. Such room-bounding structures may be utilized as part of a modular room that includes one or more utility connections for connecting a utility system to the modular room.