Within the senior citizen housing development, certain related accessory facilities may be permitted, either in a separate building or in combination with a building containing dwelling units, such as dining facilities, self-service laundries, lounges, game rooms, workshops, for use of the occupants and not for general public use. Such facilities shall be subordinate to the residential character of the development and with no outside advertising. Any such accessory facilities shall require specific approval of the Planning Board. At a minimum, the Planning Board shall require all senior citizen housing developments to have a common meeting room of sufficient size, in the Planning Board's judgment, to meet the needs of the development.