Offices for or the conduct of any customary home occupations in the dwelling used as a private residence, provided such use does not involve any extension or modification of said dwelling which will alter its outward appearance as a dwelling, and provided such use does not involve any outward evidence of such use other than a sign not exceeding four square feet in area placed upon the premises. There shall be at least 720 square feet of actual living quarters for the use of such person and his/her family in the dwelling house, exclusive of the area used in such home occupation, and exclusive of basement, attached garages, attached porches, and accessory buildings, and the actual living quarters shall be not less than the area used in such home occupation. One off-street parking space shall be provided for each 50 square feet of floor area used for the home occupation or business in addition to the required off-street parking space for residential use.