What is a co-op alteration agreement, and why does my board require one?

Every NYC co-op operates under an Alteration Agreement — a contract between the shareholder, the contractor, and the cooperative corporation that must be fully executed before any DOB filing or physical work can begin. Major managing agents (FirstService Residential, Douglas Elliman Property Management, Brown Harris Stevens, Rose Associates, Halstead) each maintain their own template, and the board's House Rules supplement it with building-specific addenda.

The legal foundation is the proprietary lease and the Business Corporation Law §501 — a shareholder owns shares plus a leasehold, not real estate, so any modification to the unit's structure, plumbing, electrical, or risers requires the corporation's consent as the actual owner of the building. The Alteration Agreement is how that consent gets memorialized.

Standard provisions include: working hours (typically 9 a.m.-5 p.m. weekdays, no weekends, no holidays — codified in NYC Noise Code §24-218), floor-protection and elevator-padding requirements, an insurance schedule (commonly $2-5M general liability, workers' comp per NY WCL §10, $1M umbrella, with the corporation and managing agent named as additional insureds), an indemnification clause, and an alteration deposit that ranges from $5,000 on a cosmetic refresh to $50,000+ on a full gut. The agreement also specifies that all wet-over-dry work requires an engineer's letter, all gas work requires a licensed master plumber's sign-off and a DOB NOW: Plumbing LAA, and any structural change requires the building's engineer of record to review the load path.

The board review usually runs 4-8 weeks. Submission package: signed Alteration Agreement, full architectural plans stamped by an RA or PE, contractor's HIC license and insurance, and the alteration deposit check. The board can — and routinely does — reject scope items: relocating a kitchen over a downstairs neighbor's bedroom, opening a load-bearing wall without a peer-reviewed structural plan, or moving a wet wall off the existing riser.

No board approval, no DOB filing. Filing without the alteration agreement signed and on file is a breach of the proprietary lease and grounds for the board to seek an injunction halting work and pursue eviction proceedings under RPAPL §711.