N.Y. Real Prop. Acts. Law § 339-k

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