411 ROOF STRUCTURES (R)

411.1 To exercise a reasonable degree of architectural control upon roof structures in all districts, housing for mechanical equipment, stairway and elevator penthouses, and, when not in conflict with An Act To Regulate the Height of Buildings in the District of Columbia, approved June 10, 1920 (36 Stat. 452; D.C. Official Code, §§ 6-601.01 to 6-601.09, on apartment building roofs, penthouses for (a) storage, showers, and lavatories incidental and accessory to roof swimming pools or communal recreation space located on that roof; and (b) other enclosed areas, within the area permitted as a roof structure, used for recreational uses accessory to communal rooftop recreation space, shall be subject to conditions and variable floor area ratio credit specified in this section.

411.2 When located below, at the same roof level with, or above the top story of any building or structure, penthouses (as outlined in § 411.1) shall be subject to the provisions of §§ 400.7, 530.4, 630.4, 770.6, 840.3, or 930.3 when applicable, and to the conditions and variable floor area ratio specified in this section.

411.3 All penthouses and mechanical equipment shall be placed in one (1) enclosure, and shall harmonize with the main structure in architectural character, material, and color.

411.4 When roof levels vary by one (1) floor or more or when separate elevator cores are required, there may be one (1) enclosure for each elevator core at each roof level.

411.5 Enclosing walls from roof level shall be of equal height, and shall rise vertically to a roof, except as provided in § 411.6.

411.6 When consisting solely of mechanical equipment, the equipment shall be enclosed fully as prescribed in §§ 411.3 and 411.5, except that louvers may be provided. A roof over a cooling tower need not be provided when the tower is located at or totally below the top of enclosing walls.

411.7 Solely for the uses designated in this section, an increase of allowable floor area ratio of not more than thirty-seven hundredths (0.37) shall be permitted.

411.8 Roof structures shall not exceed one-third (1/3) of the total roof area for those districts where there is a limitation on the number of stories.

411.9 In addition to the floor area ratio allowed by § 411.7, mechanical equipment owned and operated as a roof structure by a fixed right-of-way public mass transit system shall be permitted in addition to roof structures permitted in this section.

411.10 [REPEALED]

411.11 Where impracticable because of operating difficulties, size of building lot, or other conditions relating to the building or surrounding area that would tend to make full compliance unduly restrictive, prohibitively costly, or unreasonable, the Board of Zoning Adjustment shall be empowered to approve, as a special exception under § 3104, the location, design, number, and all other aspects of such structure regulated under §§ 411.3 through 411.6, even if such structures do not meet the normal setback requirements of §§ 400.7, 530.4, 630.4, 770.6, 840.3, or 930.3, when applicable, and to approve the material of enclosing construction used if not in accordance with §§ 411.3 and 411.5; provided, that the intent and purpose of this chapter and this title shall not be materially impaired by the structure, and the light and air of adjacent buildings shall not be affected adversely.

411.12 For purposes of this section, the rules of interpretation provided in §§ 411.13 through 411.17 shall

be applicable.

411.13 In computing the floor area ratio of a roof structure, the aggregate square footage of all levels or floors contained within a roof structure measuring six and one-half feet (6 ½ ft.) or more in height shall be included in the total floor area ratio permitted.

411.14 Areas within curtain walls without a roof used where needed to give the appearance of one (1) structure shall not be counted in floor area ratio, but shall be computed as a roof structure to determine if they comply with § 411.8.

411.15 For the administration of this section, mechanical equipment shall not include telephone equipment, radio, television, or electronic equipment of a type not necessary to the operation of the building or structure. Antenna equipment cabinets and antenna equipment shelters shall be regulated by chapter 27 of this title.

411.16 For purposes of this section, skylights, gooseneck exhaust ducts serving kitchen and toilet ventilating systems, and plumbing vent stacks shall not be considered as roof structures.

411.17 Roof structures less than four feet (4 ft.) in height above a roof or parapet wall shall not be subject to the requirements of this section.

SOURCE: § 3308 of the Zoning Regulations, effective May 12, 1958; as amended by: Final Rulemaking published at 33 DCR 3975 (July 4, 1986); Final Rulemaking published at 33 DCR 4682 (August 1, 1986); Final Rulemaking published at 33 DCR 7308 (November 21, 1986); Final Rulemaking published at 47 DCR 9741-43 (December 8, 2000), incorporating by reference the text of Proposed Rulemaking published at 47 DCR 8335, 8370 (October 20, 2000); as amended by Final Rulemaking published at 54 DCR 3064(April 6, 2007); as amended by Final Rulemaking published at 55 DCR 0034 (January 4, 2008); as amended by Final Rulemaking published at 55 DCR 1803 (February 22, 2008).