New York Chapter The Founding Chapter of The American Institute of Architects

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New York Chapter The Founding Chapter of The American Institute of Architects AIA New York Chapter Zoning Study: - Bulkhead Study 24 July 2006 Introduction The following document, prepared by The AIA

The current limits on rooftop obstructions under Quality Housing Zoning often do not permit adequately sized bulkheads on sites under 125 feet in width.

We have identified below the elements of a building that require rooftop obstructions, as well as specific examples of building designs compromised by the current New York zoning regulations on

The following are examples of rooftop obstructions: 279 Central Park West 355 East 33 rd Street 211 West 18th Street East 51 st and First Ave Building Elements Requiring Bulkheads When traction

1 New York Chapter The Founding Chapter of The American Institute of Architects AIA New York Chapter Zoning Study: - Bulkhead Study 24 July 2006 Introduction The following document, prepared by The AIA New York Chapter, has been developed to address concerns raised by Chapter members and others about rooftop obstructions permitted for new residential buildings in New York City. The current limits on rooftop obstructions under Quality Housing Zoning often do not permit adequately sized bulkheads on sites under 125 feet in width. (Bulkheads are enclosures of stairs to the roof, mechanical spaces and overruns for elevators). We have identified below the elements of a building that require rooftop obstructions, as well as specific examples of building designs compromised by the current New York zoning regulations on bulkheads, and have proposed alternative zoning text to resolve the potential conflict between efficient building layouts and appropriate architectural proportions. The following are examples of rooftop obstructions: 279 Central Park West 355 East 33 rd Street 211 West 18th Street East 51 st and First Ave Building Elements Requiring Bulkheads When traction elevators are used in most mid-rise and all high-rise buildings an elevator machine room is required above the elevator shaft. Bulkhead size does not significantly change with the footprint of a building. Buildings with a small street frontage have rooftop obstructions similar to those of larger buildings: bulkheads for two stairs and an elevator and sometimes a water tank. The current Quality Housing zoning text does not address this fact. This is typically not an issue in Height Factor regulations because bulkheads are set back from the front façade of a building and hence do not penetrate the sky exposure plane. 536LaGuardia Place New York, NY , tel; , fax info@aiany.org web:

AIA New York Chapter Zoning Study: - Bulkhead Study Rooftop equipment varies based on building height.

Buildings over 60 feet in height use a traction elevator, which, depending on elevator speed, requires about a 20-foot-high rooftop structure, including the overrun and elevator machine room.

Buildings up to 120 feet tall often do not require a water tank either, using a booster pump to provide water for the fire suppression system, except when cellar space is not available, usually due

2 AIA New York Chapter Zoning Study: - Bulkhead Study Rooftop equipment varies based on building height. Typically, buildings up to 60 feet in height can use a hydraulic elevator, which requires a 12-foot-high rooftop structure. Buildings over 60 feet in height use a traction elevator, which, depending on elevator speed, requires about a 20-foot-high rooftop structure, including the overrun and elevator machine room. Typically, buildings under 65 feet in height (six stories) do not require a water tank, using street pressure to provide water for the fire suppression system. Buildings up to 120 feet tall often do not require a water tank either, using a booster pump to provide water for the fire suppression system, except when cellar space is not available, usually due to high bedrock. Buildings over 120 feet in height often have a water tank; it is typically required for buildings over 300 feet in height. Tanks are typically placed on top of elevator bulkheads because they need to be a significant distance above the top sprinkler or plumbing fixture to provide adequate water pressure. Depending on tank size, the rooftop obstruction (elevator overrun, machine room and water tank) would require more than 30 feet in height. The following table gives dimensions for typical rooftop obstructions. Typical Rooftop Dimensions Note: All dimensions are approximate Stair Bulkhead (Two typically required) Scissor Stair Bulkhead Elevator Overrun and Machine Room (Per Elevator) Water Tank (Varies depending on building size) Analysis of Current Zoning Regulations Zoning Resolution sections 23-62, 24-51, and limit rooftop obstructions to 30 feet in width, with an aggregate front-wall surface area of four times the building frontage. The following excerpts of are typical of the other cited sections: Permitted Obstructions In all Residence Districts, except as provided in Section (Permitted obstructions in certain districts), the following shall not be considered obstructions and may thus penetrate a maximum height limit or front or rear sky exposure planes (d) Elevators or stair bulkhead, roof water tanks or cooling towers (including enclosures), each having an aggregate width of street walls equal to not more than 30 feet. However, the product, in square feet, of the aggregate width of street walls of such obstructions facing each street frontage, times their average height, in feet, shall not exceed a figure equal to four times the width, in feet, of the street wall of the building facing such frontage... The limitation described above penalizes sites in districts with a height limit, and creates particular difficulties for smaller sites (up to 125 feet in width). Rooftop structures and equipment include code-mandated stairs, elevator overrun, elevator machine room, and possibly a water tank, air handling equipment, solar panels, etc. Attached are five examples of buildings that had to be redesigned to 24 July 2006 Page 2

3 AIA New York Chapter Zoning Study: - Bulkhead Study meet the requirements of the Zoning Resolution, typically at an increased cost and complication to the building design. On each sheet on the left is the preferred, non-complying scheme; the image on the right shows how the bulkhead had to be modified to meet the current regulations. The Department of City Planning has acknowledged the issue described above in drafting new zoning text for special districts for the Hudson Yards (93-41, below), Downtown Brooklyn ( ), and the West Chelsea District (98-42). In these districts the text allows a front bulkhead-wall surface area of eight times the building frontage or 20 percent of the building s lot coverage and a maximum height of 40 feet Rooftop Regulations (a) Permitted obstructions The provisions of Section (Permitted Obstructions) shall apply to all buildings within the Special Hudson Yards District, except that elevator or stair bulkheads, roof water tanks, cooling towers or other mechanical equipment (including enclosures), may penetrate a maximum height limit provided that either the product, in square feet, of the aggregate width of street walls of such obstructions facing each street frontage, times their average height, in feet, shall not exceed a figure equal to eight times the width, in feet, of the street wall of the building facing such frontage or, the lot coverage of all such obstructions does not exceed 20 percent of the lot coverage of the building, and the height of all such obstructions does not exceed 40 feet This is a good solution in zoning districts of R8 and above. In an R6 district, however, this regulation can permit a 40-foot-tall bulkhead on a building up to 50 feet tall, which the AIA Chapter feels is inappropriate massing, creating a bulkhead that is out of scale with the height of its building. Proposed Zoning Text What is the appropriate massing that will permit necessary rooftop bulkheads and equipment and yet keep in scale with the size of buildings? Based on an analysis of permitted building massing using Quality Housing in the R6 through R10 districts, and rooftop equipment requirements, the AIA Chapter recommends that the following be adopted to address the problems we have described: [Sec.] Permitted Obstructions (d) Elevator or stair bulkheads, roof water tanks, cooling towers or other mechanical equipment (including enclosures), provided that: (1) for all buildings, the product, in square feet, of the aggregate width of street walls of such obstructions facing each street frontage, times their average height, in feet, shall not exceed a figure equal to eight times the width, in feet, of the street wall building facing such frontage, (2) for buildings 120 feet in height or more, as an alternative to (1) above, the lot coverage of all such obstructions does not exceed 20 percent of the lot coverage of the building and the height of all such obstructions does not exceed 40 feet. All such obstructions shall be no closer than 20 feet to a wide street and 25 feet to a narrow street. *** [Additionally change Sec , and Sec to read the same] The current requirements are also an impediment to the installation of solar panels and other rooftop energy conservation/co-generation devices, since these types of mechanical equipment are currently not even permitted as obstructions in the general requirements of the Zoning Resolution. (They are so permitted under 24 July 2006 Page 3 ***

4 AIA New York Chapter Zoning Study: - Bulkhead Study the revised standards the City Planning Commission is using in its new special districts which list a generalized other mechanical equipment as a permitted obstruction. No such category exists in the general provision.) Certainly, solar panels consume an overwhelming share of the allotment for permitted obstructions and thus might be rejected because of this issue, an unfortunate consequence. We recommend making them a permitted obstruction as has been the case in new special districts. The attached diagrams summarize the R6, R7 and R8 Quality Housing bulk regulations, assuming a 50-foot wide site. The diagrams illustrate a rooftop obstruction envelope of 400 square feet for buildings under 120 feet in height, and a rooftop obstruction of 40 feet in height for buildings 120 feet and greater in height (R7X; R8-wide street, outside Core; R8A; R8X), generally documenting the problem we are raising. Subm A. Radzicki, M. Ginsberg & M Parley 24 July 2006 Page 4

ARTICLE 987. PD 987. PD 987 was established by Ordinance No , passed by the Dallas City Council on June 14, (Ord.

ARTICLE 987. PD 987. PD 987 was established by Ordinance No , passed by the Dallas City Council on June 14, (Ord. ARTICLE 987. PD 987. SEC. 51P-987.101. LEGISLATIVE HISTORY. PD 987 was established by Ordinance No. 30512, passed by the Dallas City Council on June 14, 2017. SEC. 51P-987.102. PROPERTY LOCATION AND SIZE.