(1) Statement of Purpose. This district is primarily intended to be used in neighborhoods having narrow and/or shallow lots and where the one thousand four hundred forty square-foot minimum lot size requirement of certain districts may be considered as too restrictive to result in utilization of lots in those districts. Dwellings within the district shall be limited to single-family occupancy. In lieu of providing specified minimum lot sizes, a sliding ratio of open space to gross floor area is outlined, which depends on the height of the unit in stories, and insures that a certain percentage of usable open space is provided for each dwelling unit. Primarily because of the size of such lots, off-site accessory parking is permitted, under certain terms and conditions.
For purposes of determination of what constitutes a "lot," structures are to be considered as group dwellings, and one or more units are permitted on the lot. It is not necessary that each unit have its own street frontage and the area regulations for the district must be complied with for each designated "lot."

(2) Use Regulations. The specific uses permitted in this district shall be the erection, construction, alteration or use of one or more structures and/or land for:

(a) Detached, semi-detached or attached single-family dwellings;

(b) Uses permitted in "R-3" Residential District, subject to all qualifications imposed on such uses;[34]

(3) Area Regulations.

(a) Lot Width. The minimum lot width shall be twelve feet;

(b) Lot Area. Lot area shall not be less than the gross floor area of the building divided by the Floor Area Ratio. The permitted amount of gross floor area and floor area ratio shall be determined as specified in §14-220.1(3)(c), below;

(c) Gross Floor Area. The gross floor area shall not exceed lot area multiplied by the floor area ratio specified as follows:

(.1) One-story building - eight-tenths.

(.2) Two-story building - one and thirty-three one-hundredths.

(.3) Three-story building - one and seventy-seven one hundredths.

(d) Occupied Area. That portion of the lot permitted to be occupied by buildings shall be determined by the open area regulations for this district;

(e) Open Area. For purposes of determining usable open area, the open area provided shall be designated as either Required or Usable Open Area and Other Open Area, as follows:

(.1) Required Open Area. The Required Open Area shall consist of those yards herein specified and, in the aggregate, shall consist of a minimum of twenty-five percent of the total gross floor area permitted on the lot. Parking areas, including access roads and driveways shall not be included as part of the Required Open Area of the lot;

(.2) Other Open Area. Other Open Area shall consist either of those yards permitted but which are of insufficient dimension to be included as part of the Required Open Area or on-site open air parking areas, including access roads and driveways;

(f) Building Set-back Line. No building set-back shall be required in this district;

(g) Yards.

(.1) Front Yards. Front yards shall not be required in this district. If provided, they must be a minimum of eight feet in depth to be considered as part of the Required Open Area.

(.2) Side Yards and Courts. When side yards or courts are used, except inner courts and open courts between the wings of the same building which are governed by the provisions of § 14-231(1), they shall be provided as follows:

(.a) Side yards and courts shall be a minimum of nine feet in width to be considered as part of the Required Open Area.

(.b) Side yards and courts may be permitted as part of Other Open Area to a minimum of five feet in width.

(.3) Rear Yards. When rear yards are used, they shall be provided as follows:

(.a) Rear yards shall be a minimum of nine feet in depth to be considered as part of the Required Open Area.

(.b) Rear yards may be permitted as part of Other Open Area to a minimum of five feet in width.

(4) Height Regulations.

(a) The maximum height of a dwelling shall be thirty-five feet above the average ground level at the base of the building, but in no case over three stories;

(b) The permitted height of non-residential buildings shall be thirty-five feet, except that one foot of additional height may be added for each additional foot the building sets back from all lot lines; provided, however, that the maximum height of any such building shall be sixty feet (subject to the provisions of § 14-231(2)).

(5) Off-street Parking. Off-street parking shall be provided in accordance with § 14-1400 of this Title; provided, however, that accessory parking areas shall be located within a distance of two hundred feet of the dwelling units they serve. In addition, if parking is provided on another lot: (a) said lot must be deeded with the primary lot for which parking is accessory; (b) said lot must also be zoned Class "R-20" Residential District; and (c) off-site parking areas designated for parking for specified units may not be deleted as accessory parking and the land use changed, unless replacement of an identical number of parking spaces is provided in accordance with the provisions of this Title.