Alteration Agreements for NYC Co-ops and Condos: A Board and Owner Guide
How alteration agreements actually work in NYC buildings — clauses, insurance requirements, board process, completion sign-off, and the mistakes that cost buildings money.
Frequently asked questions
Does every renovation need an alteration agreement?
Most do. Any work that touches plumbing, electrical, gas, structure, means of egress, HVAC, or building common elements requires a signed alteration agreement in nearly every NYC co-op and condo. Pure cosmetic work (paint, replacing a fixture with an identical one, hanging shelves) typically does not. The building's specific threshold is in the bylaws and the proprietary lease — check those before assuming an exemption.
What if the owner refuses to sign the alteration agreement?
Then no work proceeds. In a co-op, the proprietary lease almost always conditions any alteration on written board consent — performing work without that consent is a lease default and grounds for cancellation. In a condo, the bylaws and declaration give the board injunctive remedies. Either way, the board's first step is a written cease-and-desist; the next step is counsel. Owners do not get to skip the agreement.
How do we enforce a violation of the agreement?
The agreement itself is the enforcement tool — it should give the board the right to halt work, draw against the deposit for remediation, pursue specific performance, recover legal fees, and (in a co-op) treat persistent violations as a lease default. The board's job is to invoke the contract early and in writing. Verbal warnings are rarely enforceable later. Counsel should send the first formal notice; informal escalation by the managing agent tends to produce informal responses.
Does this apply to condos too, or just co-ops?
Both, with structural differences. Co-op authority flows from the proprietary lease, which is a strong contractual basis. Condo authority flows from the declaration and bylaws plus the board's general power under Real Property Law Article 9-B — also strong, but with somewhat different remedies. The practical alteration agreement looks nearly identical in both contexts. The legal basis for enforcement is what differs, and your counsel should draft the agreement to match.