(a)   Fences, walls and hedges are permitted in any required yard, or along the edge of any yard provided that no fence, wall or hedge in a front yard area exceed four (4) feet in height. Fences, walls or hedges along side or rear property lines shall not exceed a height of six (6) feet above the grade. Informal plantings may be higher than six (6) feet.
   (b)   Any fence, wall, or hedge shall be well maintained and shall not be hazardous or disturbing to existing or future neighboring uses.