By PATRICK McGEEHAN

The owners of more than 3,200 apartment buildings in New York City reached an agreement on a new labor contract with the union that represents about 30,000 doormen, porters, janitors and building superintendents, averting a strike that was due to begin at 7 a.m. Wednesday.

The talks went right to the wire, as they often have in the past, with the union resisting the owners’ demands for cuts in health care and other benefits. In the end, the owners agreed to a new four-year contract that includes a total pay increase of nearly 10 percent and no significant cuts in benefits for the workers, an official with the union, Local 32BJ of the Service Employees International Union, said at 12:20 a.m. Wednesday.

Representatives of the owners had negotiated with union officials for several days leading up to the expiration of a four-year contract. The main points of contention had been the owners’ demand that the workers share some of the cost of their medical and dental benefits.

A strike would have disrupted the daily routines of hundreds of thousands of middle-class residents from upper Broadway to Brownsville, as well as affluent owners of Park Avenue penthouses. Along with picket lines in front of many of their homes, they would be confronted with the loss of the people who sign for their packages, carry their luggage and let the pizza deliverers and dog walkers into the building. Residents of many buildings have been asked to volunteer to pitch in to sort the mail, announce visitors by intercom, operate elevators and haul garbage to the curb if necessary.