For the purposes of this subsection, the area of the single-family house shall be the total area of all of the stories of the house, measured from the outside faces of the exterior walls, including the areas of enclosures and additions to the house that are proposed to be made for the purpose of an accessory apartment. It shall also include the area of basements. The area of the single-family house shall not include roofed but unenclosed areas, such as porches and carports. Also, for the purposes of this subsection, the net floor area of the accessory apartment shall not include any hall providing the unit with access to the outdoors. The accessory apartment is limited to a maximum of two bedrooms.