LYNN – Consecutive winter storms have left deep snow on the rooftops of homes and public buildings, threatening them with collapse as evidenced by several incidents on the North Shore.City officials took action Friday, hiring contractors to remove the snow, a laborious task done with shovels and wheelbarrows.Inspectional Services Dep-artment Director (ISD) Michael Donovan said many buildings are rated to support 20 pounds per cubic inch, but deep snow can quickly surpass that threshold.”Two feet of snow is a lot of weight on a roof,” he said.On Friday, crews from Trahant Roofing shoveled snow from the roofs at City Hall, Ingalls Elementary School and English High School. Other private contractors were dispatched to different public buildings.”When the snow gets to 24-30 inches, it’s time to get it out of there,” said contractor and Ward 2 City Councilor William Trahant Jr. “ISD inspected the city buildings and sent out contractors to remove the snow. The drifts were 4-5 feet tall on top of City Hall and 5-6 feet on the Ingalls School.””The drifts get bigger wherever you have a roof that meets a higher part of the building,” he added.Trahant said using a snowblower would damage the roof.”We do it with shovels and wheelbarrows. We dig out the vents for the heaters and the exhausts and all the roof sewers. They’re talking rain so we’re removing as much as possible, picking the heaviest drifts and dumping them over the side of the building if we have access to the edge. We skim it down to six or seven inches. It’s the only way to do it,” he said.Trahant said it took three hours to shovel the Ingalls School roof. “We’re just being proactive,” he said.