In all Residential Zone Districts, off-street parking shall be furnished for all new buildings or additions to buildings at a ratio of two usable off-street parking spaces for each new dwelling unit on the premises upon which the dwelling unit is located. In all Residential Zone Districts permitted nonresidential uses shall be provided with two off-street parking spaces exclusive of any access drives or aisles within the parking area for every 200 square feet of floor area, or any fraction thereof, of any building used for said use exclusive of a private garage. Any permitted nonresidential use which is on the same lot with a permitted residential use shall be provided with off-street parking for each of the uses and the computation for each use shall be made separately and cumulatively. All off-street parking spaces as required by this subsection shall be provided with adequate access drives and aisles as defined in Section 34-5.