Disclaimer: This post is based on a partial review of ZRD1 approvals. A more thorough analysis of all ZRD1’s approved by the department may lead to alternate conclusions. In addition, department practice may have evolved in more recent approvals. The ZRD1 Project strives to be accurate and fair-minded and we welcome clarifying information from the department or anyone who has better information on the subject discussed below. Please email info@zrd1.com with any questions or concerns.

July 2024 Update - The City of Yes for Economic Opportunity text amendment makes portions of these blog posts obsolete.  Some text sections have been reorganized and links to section references may no longer be accurate.  More importantly, the text amendment opens a new chapter in New York City zoning analysis.  Until such time that these posts can be updated, please consider this post as representative of NYC zoning prior to the enactment of the City of Yes text amendments.

Mechanical deductions represent enormous value to developers in New York City. Residential floor area can be increased by 2 to 3%, while commercial floor area, especially in a flood zone, can increase by as much as 6 to 10%. Mechanical deductions can add thousands of square feet to the project. But what, exactly, may be deducted?

The Zoning Resolution simply states that:

Should we include the walls that enclose mechanical shafts and mechanical rooms as floor area? And what about the stairs and elevator shafts that pass through floors that are entirely devoted to mechanical equipment? Over the years the Department has approved of dozens of ZRD1’s about these issues. This post will explore some of these approvals in an attempt to understand current Department practice.

Categories of Mechanical Deductions

Mechanical deductions can be grouped into three categories: shafts, rooms and floors. As we will see, the Department’s level of scrutiny appears to increase in proportion to the potential amount of the floor area deduction.

Shafts: Mechanical and Plumbing

Obviously, the voids created by vertical ductwork and pipes constitute mechanical space and should be deducted from the zoning floor area. But what about the walls that enclose these spaces? It appears that (at least for now) the Department allows for the enclosing shaft walls to be deducted from the building floor area. This approval for 590 Fulton Street is one of many that allowed the deduction of enclosure walls:

Shafts: Electrical

A common plan exam objection relates to the deduction of electrical shafts and rooms. But Department practice has consistently allowed for the deduction, inclusive of electrical service panels, conduits, risers, and chases. In addition, a closet or room containing such equipment is also deductible, provided it is minimally sized in accordance with manufacturer or code requirements. Many ZRD1 approvals illustrate this Department practice, such as this one issued for 7 West 21st Street.

Shafts: Telecommunications

It is important to note that low voltage (IT and telecommunications) equipment is not recognized by the Department as being deductible. However, a dedicated fire alarm riser and associated closets dedicated to the fire alarm system have been considered deductible, as per this ZRD1 approval for 275 Fourth Avenue (Brooklyn):

Shafts: Refuse Chutes

Refuse Chutes and their enclosures have been confirmed to be deductible through several ZRD1's, such as this one for 553 West 30th Street. In this case, the diagram of the trash room indicates that the deduction is taken to the outside face of the enclosure walls:

The Department writes:

Mechanical Rooms

Mechanical rooms contain the equipment that typically communicates with the mechanical shafts. Usually a designer will keep these rooms compact, but there are times when an oversized mechanical room makes sense, especially if the floor space within the mechanical room is deductible.

This 2014 ZRD1 approval for 34 West 38th Street highlights common themes in Department approvals of mechanical room deductions. The Department writes:

The approval goes on to allow for the deduction of the entire room where 90 percent of the room may be excluded from floor area as per the preceding items and the remainder of the room is unoccupied circulation space. This is an important concept that also applies to the deduction of mechanical floors.

For some reason the Department does not usually allow for the deduction of the walls that enclose the mechanical rooms.

Mechanical Floors

The deduction of mechanical floors is nothing new. The Department has a long record of allowing it, see BSA Cal. No. 315-08-A for some interesting background information. But recent high profile projects such as 50 West 66th Street and 249 East 62nd Street pushed the idea a little too far and paved the way for the recent zoning text amendment which placed new controls on the deduction of mechanical space.

High rise buildings often dedicate one or more floors to mechanical equipment. It is common to deduct the entire floor from the floor area calculation, but plan examiners sometimes object to the practice, insisting that the elevators and stairs are not deductible. Several approved ZRD1’s confirm that the Department has allowed for the deduction of the stairs and elevators, but has established stringent criteria to determine compliance.

Back in 2012, their response to a ZRD1 for 400 Park Avenue South applied a somewhat loose standard:

By 2014, their response was a bit more stringent for the project at 34 West 38th Street:

This approval integrates the 90 percent test to determine whether the stairs and elevators are deductible. It goes on to state that “corridors and vestibules shall be counted as ‘floor area’”. That seems like an odd conclusion, as these areas are fundamental elements of the exit access. In my opinion, if we can deduct the stairs then we should be able to deduct other egress elements.

Perhaps Department policy has evolved, as this ZRD1 approval for 1230 Madison Avenue in 2019 did not include any reference to the vestibule area counting towards floor area:

Summary

Most shafts and their enclosing walls are deductible. The interior area of mechanical rooms can be deducted if they are minimally sized or as required per manufacturer specifications. Entire floors can also be deducted, but the mechanical room layouts need to be justified by manufacturer requirements and occupy at least 90% of the open area of the floor.

If you have more recent experience with this topic, please email info@zrd1.com