top of page

#TTCTALKS with James Saisakorn: “The Sliver Law”

Welcome to the second installment of our new series, #TTCTalks! This year, we will be featuring blog posts written by our management team specifically written for the blog – here, you’ll hear professional architects and designers’ takes on patterns in the industry, their experiences in the field, and more – all from a first hand perspective. We are excited to share our second chat, written by The Turett Collaborative partner and architect James Saisakorn! Scroll down to read his post, and stay tuned for more #TTCTalks coming throughout the year.

We are often asked to weigh in about a site’s need to comply with the Sliver Law. It comes up more often than almost any other zoning issue. But what is the Sliver Law anyway and why does it have such an impact on development? Here is a typical scenario, You are a developer and have found the ideal site in NoMAD, near enough to new development projects on Broadway south of Herald Square. The broker explains that there are opportunities to develop a significant amount of square footage on the site, and at first glance you agree.

Located on 30th street, the zoning maps show that the site is within a zoning district with very high density that allows for residential development. It’s not in a Landmarks District so there are no restrictions to the height of the building from a Landmark’s perspective. You say to yourself, it’s all too good to be true, and unfortunately your suspicions are correct.

Sections 23-692 and 33-492 of the NYC Zoning Resolution, often referred to as the Sliver Law, were enacted in 1983 to limit the height of narrow buildings in high density zoning districts (R7-2, R7D, R7X, R8, R9, R10). These districts have comparatively high FARs (floor area ratio) allowances where FAR is the ratio of buildable floor area to the size of a zoning lot’s footprint. For example, an FAR of 10.0 would allow a developer to build a building 10.0 times the size of the lot’s footprint.

Prior to 1983, some developers began purchasing small lots in high density districts. Their efforts to maximize the allowable floor area on the site resulted in what is known as “slivers”. These were disproportionately tall and narrow buildings that were out of context with the surrounding volumetric character of a neighborhood.

785 8th Avenue, from Microsoft Maps

According to the regulations of the Sliver Law, narrow buildings, those with lot frontages of less than 45’-0” in width, are restricted to a height equal to 100’-0” or to the width of the street whichever is less. There are a few exceptions to the rule. If the building is located on a narrow street between two taller buildings, the building may rise to the height of the lower of the two. If the building is on a wide street between two taller buildings, the building may rise to the height of the taller of the two. It should also be noted that in some special zoning districts such as the Special Lower Manhattan District (LM) or the Tribeca Mixed Use District (TMU), the stipulations of the Sliver Law are either modified or don’t apply.

Let’s have another look at the hypothetical site on 30th street, a narrow street with a width of 60’-0”. The site, which is 25’-0” x 100’-0”, sits between two buildings both of which are 50’-0” tall. The zoning map indicates that the site is within an R10A district. Off the bat, the description “R10A” tells quite a bit of information. The R indicates primarily residential only development, the 10 indicates the degree of density allowed, and a letter suffix such as “A” indicates that the area is subject to contextual zoning requirements where minimum and maximum base heights and maximum base heights control the developable envelope.

In an R10A residential district,Section 23-662 of the zoning resolution indicates that the maximum height of the residential building you plan to develop can be 185’-0”. This seems like excellent news, however further analysis of the zoning resolution indicates that this is not the case. The site is narrow (less than 45’-0” wide) and it sits on a narrow street. Because of these two factors, your building is limited to 100’-0” in height or the width of the street whichever is less. In this case, the 60’-0” width of 30th Street limits the height of the new building to only 60’-0” in height or the width of the street whichever is less.

image from The Turett Collaborative

In the example above, what appears to be a great development opportunity, that will potentially result in a tall building becomes less attractive when the Sliver Law is factored into the equation. When searching for development sites, always engage a qualified architect or zoning specialist to review the property and prepare a zoning analysis before a decision is made to move forward with a purchase. The data provided by a broker’s property report and sites like Property Shark may not always tell the full story.


bottom of page