Plaintiff, commercial tenant, waived rights under NY Real Property Law section 227 as part of commercial lease. Later, after persisitent flooding allegedly caused by another tenant, plaintiff vacated the premises, stopped paying rent and commenced action for breach of commercial lease, breach of covenant of quiet enjoyment, damages and negligence, claiming constructive eviction. The Appellate Division held that defendant's summary judgment motion should have been granted where RPL section 227 rights had been waived. Breach of quiet enjoyment cause of action failed although premises vacated because of failure to pay rent. Quiet enjoyment entitlement is based on the plaintiff having performed all covenants, including the payment of rent.