For zoning lots with flood-resistant buildings, the regulations for yards and open space shall be modified in accordance with the provisions of this Section.

(a)        Level of required yards

In all districts, the underlying yard regulations shall be modified to allow the level of a yard or a rear yard equivalent to be located higher than curb level, provided that it does not exceed the flood-resistant construction elevation, and the level set forth by the following regulations:

(1)        in Residence Districts, the final grade of front yards and side yards shall not penetrate a plane that begins three feet above curb level at each lot line and has a slope extending perpendicular to lot lines of one foot vertical for each 2 feet 6 inches of horizontal distance;

(2)        in Commercial and in Manufacturing Districts, for portions of zoning lots where Sections 33-29 and 43-30 (SPECIAL PROVISIONS APPLYING ALONG DISTRICT BOUNDARIES) apply, the level of front yards and side yards may be permitted to exceed curb level only pursuant to paragraph (a)(1) of this Section.

Nothing in this Section shall be construed so as to permit the creation of spaces below grade on all sides in a manner inconsistent with flood-resistant construction standards.

(b)        Permitted obstructions

(1)        Covered porches, balconies, and covered access areas

In all districts, a porch or access area covered by a roof or other permanent structure shall be permitted obstructions in any required open space or yard on the zoning lot. Where permanent structures such as balconies are located directly above a porch or access area, such balconies may exceed the width and depth standards of Section 23-13 (Balconies).

(2)        Retaining walls

In Residence Districts, retaining walls shall be permitted in front yards and side yards provided any retaining wall parallel to, or within 15 degrees of being parallel to, the street shall not exceed a maximum height of three feet, as measured from the level of the adjoining grade or planted area below such wall, so that no more than three feet of such retaining wall is visible from the street; and

(3)        Fences

In Residence Districts, portions of fences located in front yards with height greater than four feet above curb level shall be required to be no more than 50 percent opaque.

(c)        Front yard planting requirement

In R1 through R5 Districts, where the distance between the street wall and the street line is 10 feet or less, or for zoning lots with front yards that are shallower than the minimum required pursuant to the applicable district regulations, stairs, ramps or lifts that access the first story above the flood elevation shall be exempted from the area of a front yard for the purpose of calculating the planting requirements of Section 23-451 (Planting requirement).