Sec. 9-4.302.  Sub-zones.
   Sub-zones of each of the R Zones may be established.  The requirements for the parent R Zone shall apply to the respective sub-zones except as to the minimum lot area required per family and the minimum lot width.  The minimum lot area per family and lot width in each subzone shall be fixed by the use of suffix numbers on the zoning map applicable to the area.  The required lot width in any zone shall be determined in accordance with the required lot area for the zone and the applicable width set forth in this section.  In order to increase or decrease the minimum lot size for any zoned land, the zoning symbol or designation of the sub-zone shall be the same as for the parent zone except that a suffix shall be added, indicating the required minimum lot area per family in square feet and the minimum lot width.
   For the purpose of establishing sub-zones, an acre contains forty-three thousand five hundred and sixty (43,560) square feet.  The suffixes for sub-zones and their meanings shall be as follows:
Minimum Lot Suffix
Minimum Lot Area Required
Width Required
6,000 square feet
60 feet
7,000 square feet
70 feet
8,000 square feet
75 feet
9,000 square feet
75 feet
10,000 square feet
80 feet
13,000 square feet
90 feet
20,000 square feet
100 feet
30,000 square feet
125 feet
1 Ac.
43,560 square feet
150 feet
2 Ac.
87,120 square feet
150 feet
3 Ac. or more
Area equivalent to the number of acres, and fraction thereof, multiplied by 43,560
150 feet
   The following are examples of sub-zones:
   (a)   The sub-zone of the R-1 Zone which requires a minimum lot area per family of eight thousand (8,000) square feet and a minimum lot width of seventy-five (75') feet shall be R-1-8.
   (b)   The sub-zone of the R-A Zone which requires a minimum lot area per family of five (5) acres and a minimum lot width of one hundred fifty (150') feet shall be R-A-5Ac.
(§ 8112, T.O.O.C.)