Renting or subletting an apartment unit in a co-op is often a complex process. Co-ops tend to have strict guidelines regarding sublets. Without them, they risk letting in renters who do not meet their tenant/shareholder qualifications, which are critical to maintaining the environment the co-op has established. Co-op tenants undergo a lengthy and comprehensive application and interview process. Your co-op may require that your renter goes through a similar process.
Recently, after a non-jury trial, the Court in Terry v 241 West 111th Street, HDFC, NYLJ April 8, 2013 (Sup, NY Engoron, J, April 1, 2013):
A small leak developed in the closet ceiling of apartment 15L, a coop apartment. The Coop's engineer's opinion was that it was caused by a leak from the bathroom in apartment 16L. The 16L apartment owner retained our firm and an engineer whose opinion was that the leak was not emanating from our client's bathroom but rather from pipes higher up in the building.
When I represent a client who is purchasing a co-op or condo apartment, it is important to look into the finances of the Co-operative or Condominium. A co-op or condo owner does not just own their own apartment. The owner owns a part of the cooperative or the condominium. The financial health of the cooperative or condominium has a direct effect on the apartment owner. Whether the building's mortgage is due to be re-financed or a real estate tax abatement is about to expire are factors that would have an effect on the common charges or maintenance the owner is obligated to pay.