N.Y. Real Property Law § 339-k

Condo alteration consent: N.Y. Real Property Law § 339-k

Under N.Y. Real Property Law § 339-k, no unit owner may do work jeopardizing safety, reducing value, or adding structures without consent of affected owners.

Official text N.Y. Real Property Law § 339-k — New York

§ 339-k. Certain work prohibited. No unit owner shall do any work which would jeopardize the soundness or safety of the property, reduce the value thereof or impair any easement or hereditament, nor may any unit owner add any material structure or excavate any additional basement or cellar, without in every such case the consent of all the unit owners affected being first obtained.

Text as published in the 2026 snapshot of the code.

Source: Vaquill Open US Law, compiled from official state publishers (huggingface.co), reproduced under license CC BY 4.0.

Read this provision at the official source →

What it actually says

A single sentence with two limbs. No unit owner shall do any work which would jeopardize the soundness or safety of the property, reduce the value of it, or impair any easement or hereditament - and no unit owner may add any material structure or excavate any additional basement or cellar - without in every such case first obtaining the consent of all the unit owners affected.

The test is stated in terms of effect on the property rather than in terms of permits. "Soundness or safety" reaches structural work: removing a wall that carries load, cutting into a slab, altering a riser. "Reduce the value thereof" is broader and vaguer, and is the limb boards reach for when work is unsightly or damages the building's standing. "Impair any easement" catches work that interferes with rights of way, light, support or service that other units or neighbors hold.

The consent required is not the board's. The text says the consent of all the unit owners affected - which may be a small group or, for structural work, everyone. In practice most condominiums layer an alteration agreement and a board approval process on top of this section through the by-laws, and § 339-j requires compliance with those by-laws. Section 339-k is the floor that exists whether or not the by-laws say anything.

When it applies

  • A neighbor removes a wall or cuts into the structure during a gut renovation.
  • An owner excavates to add a cellar or extends the unit with a new structure.
  • Work in one unit damages a riser, a stack or a shared service that other units depend on.
  • A renovation blocks or interferes with an easement over the property.
  • A board learns of structural work that was never submitted for approval.

What this section does not say

  • It is not a general renovation approval rule. Ordinary work that does not touch soundness, safety, value or an easement is not addressed here - the by-laws and any alteration agreement are.
  • It is not a noise or nuisance provision. Hard flooring replacing carpet is usually a by-laws and house-rules question, not a § 339-k question.
  • It does not name the board as the consenting party. The consent required is that of all unit owners affected.
  • It does not replace permits. Compliance with this section says nothing about the Building Code or the approvals a municipality requires.
  • It provides no remedy of its own. Enforcement runs through the by-laws and § 339-dd.

Worked examples

Invented situations, written to show how the wording bites. They are not real cases, not judgments and not precedent, and nothing here predicts what would happen in yours.

Illustrative example

The owner below removes part of a wall and cuts into the plumbing stack during a gut renovation. The floor above is now uneven and another unit has lost water pressure.

How the wording applies

No unit owner may do work that would jeopardize the soundness or safety of the property, reduce its value or impair any easement, without first obtaining the consent of all the unit owners affected. Note who consents: not the board, but the owners affected, which for structural work may be everyone. It turns on the effect of the work on the property rather than on whether a permit was pulled.

How the parties settled it

Work stops until an engineer both sides accept has reported, the owner below funds the structural remedy and the stack repair, and the affected owners' consent is recorded in writing before anything else proceeds.

Illustrative example

An owner replaces carpet with hardwood throughout. The neighbor below, kept awake by every footstep, wants this section used to have the floor taken out.

How the wording applies

This is not a noise or nuisance provision: hard flooring is ordinarily a by-laws and house-rules question rather than a § 339-k question, which is aimed at soundness, safety, value and easements. The section also provides no remedy of its own - enforcement runs through the by-laws and § 339-dd.

How the parties settled it

An acoustic underlay is retrofitted at the upstairs owner's cost with rugs in the main walkways, and the house rules are updated to say what is required of anyone changing a floor in future.

Illustrative example

A ground-floor owner wants to excavate for a cellar and put up a small structure in the yard, and assumes board approval is all that is needed.

How the wording applies

The second limb is explicit and does not depend on proving any effect at all: no unit owner may add any material structure or excavate any additional basement or cellar without first obtaining the consent of all the unit owners affected. Board approval under the by-laws is an extra layer rather than a substitute, and compliance with the section says nothing about the Building Code or municipal approvals.

How the parties settled it

The owner circulates the plans, obtains and records written consents from the owners affected, and agrees to indemnify the association for any damage to the common elements during the work.

Related sections

N.Y. Real Property Law § 339-i Condo Board Access Rights | N.Y. Real Property Law § 339-i N.Y. Real Property Law § 339-h Exclusive Unit Ownership: N.Y. Real Property Law § 339-h N.Y. Real Property Law § 339-cc RPL § 339-cc: rebuilding a damaged condominium, and the three-quarters rule

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We copy this text from the official publisher and re-check it against that source on every page load, but we cannot guarantee it is complete, current or free of error, and we accept no liability for any reliance on it. An amendment can take effect before a consolidation catches up. The publisher's own copy is linked below; where the two differ, it is the official one that counts.

This page reproduces the text of N.Y. Real Property Law § 339-k in force at the date shown and explains it in general terms. It is not legal advice and takes no account of the circumstances of your case, which can change the answer completely. For a live dispute, for limitation periods, and before taking any step in court, consult a qualified lawyer in New York.

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