NYC co-op boards control what you can renovate, when you can do it, and how. Roughly 70% of co-op alteration requests in Manhattan involve work that requires explicit board approval, and the rules vary by building in ways that are not disclosed in listing descriptions. A buyer who assumes that owning the apartment means doing whatever they want to it will discover the alteration agreement at the worst possible moment: after closing, when a contractor is scheduled and the board has not approved the scope.
In my 25+ years as a Licensed Real Estate Associate Broker, I have seen buyers fall in love with apartments they planned to renovate, close without reviewing the alteration agreement, and discover that the kitchen relocation they envisioned was prohibited, the washer/dryer installation they planned was not allowed, or the HVAC upgrade they needed was subject to an 18-month approval timeline. This guide covers what the alteration agreement contains, what co-op boards typically allow and prohibit, and the practical timeline for getting work approved and completed.
What Is an Alteration Agreement?
An alteration agreement is a contract between you and the co-op corporation that governs any modification to your apartment beyond basic cosmetic work like painting and furniture placement. Most co-ops require shareholders to sign and return a completed alteration agreement before any permitted renovation work begins. The document specifies the scope of approved work, the insurance requirements for contractors, the hours during which construction noise is permitted, the board's right to inspect, and the financial obligations (deposits, fees) associated with the work.
Alteration agreements are not standardized. Each co-op has its own version, shaped by its building's physical structure, its proprietary lease, and decades of board policy. The alteration agreement for a 1920s Upper West Side prewar building will look substantially different from the agreement for a 1965 post-war high-rise in Queens, because the buildings have different plumbing configurations, different floor-to-ceiling heights, different mechanical systems, and different histories of shareholder disputes over renovation damage.
Request the Alteration Agreement Before You Sign a Contract
Your attorney can request the co-op's alteration agreement as part of due diligence before you sign a purchase contract. This is standard practice and does not signal an unusual request to the managing agent. If you have specific renovation plans, review the alteration agreement with your contractor and your attorney before committing to the purchase price. Do not close on an apartment expecting to renovate it, without knowing what the alteration agreement allows.
Cosmetic Work vs. Permitted Work vs. Board-Approved Work
Co-op renovation work generally falls into three tiers:
Cosmetic work (no approval required): Painting walls, replacing light fixtures with similar fixtures, installing new flooring over existing flooring without touching subfloor, and most furniture-level changes. These typically do not require an alteration agreement or board notice, though some co-ops require notification even for cosmetic work.
Permitted work (alteration agreement required, permits filed with DOB): Any work that requires a permit from the New York City Department of Buildings requires an alteration agreement and, in most buildings, board notification if not explicit approval. This includes replacing windows, installing new plumbing fixtures, opening or closing walls, installing new flooring that requires nail-down installation, and any electrical panel work.
Board-approved work (explicit vote required before starting): Work that affects building systems, wet-over-dry configurations, or structural elements requires an explicit board vote. This includes kitchen and bathroom relocations, washer/dryer installations where not previously permitted, HVAC system installations, wet-over-dry plumbing (installing a wet room above a dry room in the unit below), and any modification to load-bearing elements.
The Wet-Over-Dry Rule: The Most Common Restriction
The wet-over-dry rule is the renovation restriction that surprises the most buyers. In most NYC co-op buildings, you cannot install plumbing in a location that is directly above an existing dry room (living room, bedroom) in the apartment below yours. The reason is practical: plumbing leaks travel down. A bathroom or kitchen placed above someone's bedroom creates a liability risk the co-op board is not willing to accept.
This rule most commonly surfaces when buyers plan to move a kitchen or bathroom from its original location. A buyer who wants to open a wall between the kitchen and living room and reconfigure the kitchen's position may discover that the new position would place the kitchen directly above a neighbor's bedroom, triggering the wet-over-dry restriction. The kitchen cannot move. The renovation scope collapses.
Before finalizing any renovation plan that involves moving plumbing, obtain the building's plumbing stack diagram from the managing agent and have your architect overlay the proposed new positions. This takes one week and costs less than one hour of architect time. It prevents a weeks-long board deliberation that ends in a rejection.
Active Co-op Listings
NYC co-ops available for purchase and renovation, subject to board alteration rules.
21 E 61ST Street #6A
Lenox Hill
304 W 88TH Street #1D
Upper West Side
Listing information provided courtesy of the Real Estate Board of New York's Residential Listing Service (RLS). Information is deemed reliable but not guaranteed. Sale listings verified. ©2026 REBNY. RLS data displayed by Keller Williams NYC.
Construction Hours and Noise Rules
NYC co-ops typically enforce narrower construction hours than NYC DOB permits. While the NYC Administrative Code (Section 24-224) generally permits construction noise from 7:00 AM to 6:00 PM on weekdays and 10:00 AM to 4:00 PM on weekends, most co-op alteration agreements restrict work to weekdays only, and many limit hours to 9:00 AM to 5:00 PM or even 10:00 AM to 4:00 PM. A handful of high-end buildings prohibit all construction during July and August or during the December holiday period.
These restrictions directly affect your renovation timeline and your contractor's pricing. A contractor who bids based on a 7:00 AM start time will rebid higher when the co-op's 10:00 AM start time cuts two hours from each workday. Get the construction hour requirements from the alteration agreement before accepting contractor bids, and include them in your request for proposals.
| Renovation Type | Typical Approval Process | Typical Timeline |
|---|---|---|
| Painting, flooring (no subfloor) | None required | Immediate |
| Kitchen renovation (same location) | Alteration agreement + DOB permit | 2-4 weeks for approval |
| Bathroom renovation (same location) | Alteration agreement + DOB permit | 2-4 weeks for approval |
| Kitchen relocation | Board vote + wet-over-dry review | 6-12 weeks |
| Washer/dryer installation | Board vote (if not already permitted) | 4-8 weeks, may be denied |
| Through-wall HVAC / split system | Board vote + architect drawings | 8-16 weeks |
| Window replacement | Board approval + building-specified vendor | 4-6 weeks, often building-mandated brand |
| Wall removal (non-load-bearing) | Alteration agreement + DOB permit | 2-4 weeks for approval |
Financial Requirements: Deposits and Fees
Most co-ops charge a refundable renovation deposit of $1,000 to $5,000 held by the managing agent during the construction period. The deposit is returned when the renovation is complete, the apartment is inspected, and no damage to common areas has been documented. Some buildings charge a non-refundable administrative processing fee of $250 to $750 for alteration agreement review, separate from the deposit.
For extensive renovations, some buildings require the shareholder to post a larger performance bond or escrow a percentage of the construction budget. If a renovation causes damage to common areas, building systems, or neighboring apartments, the deposit is applied to repairs and the shareholder may be liable for amounts exceeding the deposit.
Common Pitfalls and How to Avoid Them
The most predictable renovation failures in NYC co-ops follow a consistent pattern: the buyer assumes that board approval for a scope of work means unlimited flexibility within that scope, contractors begin work beyond the approved scope, and the managing agent halts construction pending a new application. This adds weeks, sometimes months, to a renovation that could have proceeded smoothly.
A related issue is the contractor who is not on the building's approved vendor list for certain trades. Many co-ops maintain lists of approved plumbers, electricians, or HVAC contractors for work touching building systems. Using an unapproved contractor for these trades, even one who is licensed and insured, can void the alteration agreement and trigger a stop-work order. Confirm the approved vendor list before retaining any trade contractor for system-related work.
For the complete picture of what you are buying when you purchase a NYC co-op, including the proprietary lease, house rules, and financial obligations, see the co-op vs. condo comparison. For the flip tax implications of a co-op sale after renovation, see the NYC flip tax guide. For the full board package process, see the co-op board interview guide.
Buying a Co-op You Plan to Renovate?
Milton Coste reviews alteration agreements and renovation restrictions as part of every co-op buyer representation. Know what you are buying before you close.
NYC Buyer Guide
