Assertion Supported AI assessment confidence: 95% certainty 4/5 debate potential 1/5

Mark O'Brien: Below-grade basements bypass NYC Floor Area Ratio limits

Mark O'Brien · I spent a day with a blue-collar millionaire in NYC · Jul 21, 2026 · at 12:15

Real estate developer Mark O'Brien explains how finishing cellar space maximizes usable square footage without violating municipal Floor Area Ratio limits.

0:00 / 0:17exact quote · 17.1s

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“And this is basically free square footage, because, you know, in terms of FAR, floor area ratio, they don't count a base because it's below grade, so I try to make it, and right now you're not seeing it at the best I gotta put baseboard on, finish the floor, and really spruce it up, so it feels like it's real space.”

quote is from the automated transcript, cleaned for reading: filler sounds and stutters are removed, nothing is rephrased. names can be misheard (the analysis reads context, assessments check outside sources). how →

The claim, plainly

In New York City zoning regulations, below-grade basements are excluded from Floor Area Ratio (FAR) calculations, providing developers with usable square footage without violating zoning caps.

a quote alone can be ambiguous, so this restates it with the references and context of the conversation around it resolved. AI-written; the tape below the player is the source.

Assessment

Under Section 12-10 of the New York City Zoning Resolution and confirmed by the New York Court of Appeals in Matter of Raritan Dev. Corp. v. Silva (91 N.Y.2d 98), below-grade cellar space (defined as space with more than 50% of its height below curb level or base plane) is excluded from the calculation of zoning floor area and Floor Area Ratio (FAR). While NYC zoning terminology distinguishes between a 'cellar' (>50% below grade, excluded from FAR) and a 'basement' (50%+ above grade, included in FAR), the claim and resolution criteria specifically describe below-grade space meeting statutory cellar depth criteria, which is a permissible zoning deduction providing usable floor area without counting toward FAR caps.

New York City Zoning Resolution § 12-10 explicitly excludes 'cellar space' from the definition of 'floor area'.
Under ZR § 12-10, a cellar is defined as space with more than 50% of its height below curb level or base plane.
The New York Court of Appeals held in Matter of Raritan Dev. Corp. v. Silva (91 N.Y.2d 98) that below-grade cellar space is excluded from FAR caps in residential developments.

Checked against

[1] alma-pc.com [2] simpletwig.com [3] nyc.gov [4] columbiail.gov [5] nacmiaslaw.com [6] nyc.gov [7] georgejanes.com [8] metropolisny.com

"A cellar is" "Zoning Resolution" "12-10" nyc "the floor area of a building shall not include" "cellar space" NYC Zoning Resolution definition Floor Area cellar basement "ZR 12-10" "floor area of a building shall not include" "cellar space" "floor area" "Zoning Resolution" 12-10 nyc

assessed as of 2026-09-02

This assessment is an AI reading of a public statement, made against the cited references with the confidence shown. It can be wrong. The quote, the tape and the references are all on this page; if something is off, use report an error below. full disclaimer →

Mentioned

Floor Area Ratio Mark O'Brien

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