A habitable room is one that is used for living, sleeping, eating or cooking. Bathrooms, hallways, storage rooms, utility rooms, laundry rooms and corridors are not considered habitable rooms.
A habitable room can exist anywhere inside a residentially zoned house or building, including the basement or attic, as long as it meets specific criteria for ventilation, size, heating and ceiling height, which may not apply to other rooms. It must have ventilation giving it access to outdoor air, have a ceiling height of at least 7 feet, have a heat source which can maintain a room temperature of at least 68°F and have dimensions of at least 70 square feet. A count of the number of rooms in a house usually only includes habitable rooms.