Where a residence has been erected, a six-foot fence may be erected in the rear yard, provided that, if it is on an interior lot, said six-foot fence may be erected in the rear yard to extend along the rear lot line and along the side lot lines to a point not forward of the front foundation line of the residence, and thence from said lot lines to the front point of said foundation; on a corner lot, a six-foot fence may be erected in the rear yard to extend along the rear lot line and along the side lot lines, except that no such fence shall project closer to the street fronting on a side yard than the width of the required side yard or the front foundation line, whichever shall be further from the street; and on a through lot, a six-foot fence may be erected in the rear yard along the two side lot lines, but not closer to the street adjacent to rear of premises than 40 feet. Notwithstanding the foregoing, on corner lots, fences not exceeding six feet in height may be located not closer than eight feet to the front yard line, provided the applicant demonstrates, to the satisfaction of the Commissioner of the Department of Planning, Environment and Land Management, that said fence will not interfere with vehicular traffic sight visibility. In such event, said fence shall be considered a structure requiring a building permit. All such fences shall comply with the site visibility requirements of this Code.