Requirements for front, rear and side yards may be modified under the following conditions:
(A) Cornices, eaves, steps, gutters, bay windows, fire escapes, fire balconies, fire towers and similar features may project not more than 2½ feet into any required yard.
(B) Necessary retaining walls and fences less than six feet in height, when located in the rear yard, shall be exempt from the yard requirements of this chapter, except that on a corner lot no fence more than three feet in height shall be located within any yard or building setback required along the side street line by any other provision of this chapter. The height of any fence located within a yard abutting on a street line shall be measured from the sidewalk, and if there is no sidewalk or curb, from the grade of the centerline of the street. All other fence heights shall be measured from natural grade. Terraces, steps and uncovered porches which are not in any part more than four feet above the ground floor level and not within 2½ feet of any lot line shall be exempt from the yard requirements of this chapter.
(`94 Code, App. C, Art. VI, § 12)