23-663 Tower Regulations in R9D and R10X Districts
In the districts indicated, any Quality Housing building or other structure, or portions thereof, which in the aggregate occupies not more than 40 percent of the lot area of a zoning lot (or, for zoning lots of less than 20,000 square feet, the percentage set forth in the table in Section 23-651), above a height of 85 feet above the base plane, is hereinafter referred to as a tower. Dormers permitted within a required setback area pursuant to Section 23-621 (Permitted obstructions in certain districts) shall not be counted towards tower coverage. Such tower may exceed a height limit of 85 feet above the base plane provided the base of such tower complies with the applicable street wall location and height and setback provisions of Sections 23-661 and 23-662, respectively, and provided that the tower portion complies with the following, as applicable:
(a) at all levels, such tower shall be set back from the street wall of a base at least 15 feet along a narrow street and at least 10 feet along a wide street, except such dimensions may include the depth of any permitted recesses in the street wall ;
(b) the minimum coverage of such tower above a height of 85 feet above the base plane is at least 33 percent of the lot area of the zoning lot ; however, such minimum coverage requirement shall not apply to the highest 40 feet of such tower;
(c) in R9D Districts, the highest four stories, or as many stories as are located entirely above a height of 165 feet, whichever is less, shall have a lot coverage of between 50 percent and 80 percent of the story immediately below such stories. Such reduced lot coverage shall be achieved by one or more setbacks on each face of the tower, where at least one setback on each tower face has a depth of at least four feet, and a width that, individually or in the aggregate, is equal to at least 10 percent of the width of such respective tower face. For the purposes of this paragraph (c), each tower shall have four tower faces, with each face being the side of a rectangle within which the outermost walls of the highest story not subject to the reduced lot coverage provisions have been inscribed. The required setbacks shall be measured from the outermost walls of the building, perpendicular to each tower face. Required setback areas may overlap; and
(d) in R9D Districts, for towers fronting on elevated rail lines, the outermost walls of each story located entirely above a height of 85 feet shall be inscribed within a rectangle. The maximum length of any side of such rectangle that is parallel to, or within 45 degrees of being parallel to, such elevated rail line shall be 125 feet, or 75 percent of the frontage of the zoning lot along such elevated rail line, whichever is less.