Absolutely no firewalls are allowed for a low density residential (R-1) uses or occupancies; an abutment of up to 3.20 meters from established grade level may however be permitted but solely for the purpose of supporting a carport roof; provided further that such abutment shall be constructed of perforated or decorative concrete blocks above 1.50 meters measured vertically from the established grade level; such an abutment shall not be longer than 7.00 meters or 50% of the side property line in total length, whichever is shorter