The court analogizes the situation herein to cases in which tenants have waived defects in the service of the 30-day notice terminating tenancy by failing to question the jurisdiction of the court, appearing generally in the proceeding, and asking for time within which to vacate the premises. (D’Agostino v Bernabel, 269 App Div 853.) The statute which creates the requirement that a 30-day notice must be served upon the tenant provides a condition precedent for the benefit of the tenant which must be satisfied before the landlord can use the remedy which the Legislature has made available to him. Since said condition is created solely for the benefit of the tenant, the tenant has a right to waive it, and does so when his conduct and responses are solely those of compliance, rather than repudiation.
Similarly, the court takes note of those cases in which a 90-day notice of claim must be served upon the City of New York within 90 days after a claim arises. Service of said 90-day notice is a condition precedent to the institution of a proceeding against the City of New York, just as respondent alleges that a proper rent demand is a condition precedent to the commencement of a nonpayment proceeding. When a notice of claim requirement is statutorily imposed, it is usually deemed an element of the substantive cause of action and, as such, its satisfaction must be pleaded in the complaint. However, if the responsive pleading fails to deny a material allegation of the complaint, *839said failure to refute is equivalent to an admission. (Mussinan v Willner Wood Co., 69 App Div 448; Corn v Levy, 97 App Div 48.) Similarly, an affirmative defense, if not raised in the pleading, is deemed waived. (De Lisa v Amica Mut. Ins. Co., 59 AD2d 380; CPLR 3018, subd [b].) Accordingly, and in