For the purposes of determining the yard requirements, grouped houses shall be considered as one (1) building occupying one (1) parcel subject to the following regulations:

     A. The front and rear yard shall be the same as required in the zone district where permitted, and the width of the required individual side yard shall be increased an additional width of two (2) feet for each building abutting on the same side yard.

     B. If end to end there shall be not less than ten (10) feet between the buildings.

     C. If not end to end the width of the yard between the buildings shall be not less than twenty (20) feet or less than twice the height of the tallest building, whichever is greater; provided where a roadway is constructed between the buildings the width of such yard shall be measured exclusive of the roadway width.