A backed-up chimney caused a fire that significantly damaged a Weedsport home Wednesday morning, firefighters said. Weedsport Fire Chief Tom Winslow said an investigation determined the clogged chimney caused heat to transfer into the walls of the 2698 Bell St. home. One of the residents was awake at the time of the fire and notified authorities at 1 a.m.The house's owner, Raymond Swim, and his son, Robert Swim, were both home and managed to escape uninjured, Winslow said.Winslow estimated that the fire damaged nearly 35 percent of the building and the home was uninhabitable due to the damage. The family is currently staying with relatives and Red Cross assistance was not required. Due to the cold weather, Winslow said he had to constantly rotate fire crews during the two-hour battle in order to prevent firefighters from suffering hypothermia. Also responding to the scene were fire crews from Auburn, Jordan, Elbridge, Sennett, Port Byron and Throop, according to the Cayuga County 911 center.