Zoning Text Amendment to Prevent Excessive Mechanical Voids

Posted on April, 18 2019

Due to increasing concerns regarding tall towers in 2018, Mayor de Blasio asked the Department of City Planning (DCP) to review tall mechanical voids used to increase the heights of residential towers benefiting sought after penthouses.

The NYC Zoning Resolution allows floor spaces used for mechanical equipment to be excluded from Zoning Floor Area however there has not been a limit on the height of these mechanical spaces. In recent years some towers have taken advantage of this to create mechanical spaces that are taller than is strictly necessary for the normal operation of the mechanical equipment, this has been commonly referred to as “mechanical voids.”
The Department of City Planning (DCP) conducted a study of residential buildings built in the past 10 years in R6 through R10 districts and their Commercial District equivalents. The study found that there were no excessive mechanical voids in R6 through R8 non-contextual zoning districts and their equivalent Commercial Districts. Where residential buildings can penetrate the sky exposure plane when taking advantage of tower provisions in R9 and R10 non-contextual zoning districts and their equivalent Commercial Districts, most buildings had mechanical floors ranging in height from 10 to 25 feet which larger mechanical spaces located in a mechanical penthouse or a cellar. The study found seven buildings which had excessively tall mechanical floors or multiple mechanical floors stacked close together. The height of these mechanical spaces varied between 80 to 190 feet combined.
Following an environmental assessment, City Planning Commission (CPC) review, Community Board review, Borough President review, and Borough Board review, the Department of City Planning (DCP) proposed a Zoning text amendment to the City Council via a land use application (ULURP N 190230 ZRY). This zoning amendment discourages the use of mechanical voids in residential towers in R9 and R10 non-contextual zoning districts and their equivalent Commercial Districts.
The amendment proposed that a predominantly mechanical space, or stacked mechanical floors, which are taller than 25 feet be counted as Zoning floor area. A mechanical floor is considered any floor occupied by 50% or more of mechanical space. For example, stacked mechanical floors 80 feet in height would count as four floors of floor area (90/25 = 3.6, rounded to closest whole number = 4). The amendment also seeks to prevent excessive mechanical floors located within close proximity to each other.
The City Council review period ends on May 6, 2019.
To view a summary of the text amendment see City Planning’s site here.