Front, Rear and Side Yards, Area, Frontage and Height. The front yards, rear yards, side yards, area, frontage and height provisions shall be the same as required for Residence R-1 Districts. Dwellings shall not exceed 70 feet in height. There shall be no limit on the height of nonresidential structures except that for each foot the height of such structure exceeds 70 feet the total width of the two side yards shall be increased by two feet. Structures that are accessory to the principal use of property shall not exceed 35 feet in height.