The restoration was strongly criticized during Viollet-le-Duc 's lifetime because he made the error of using slates and restoring the roofs as pointed cones , where local practice was traditionally of tile roofing and low slopes , as in this region snow was very seldom . The restoration was strongly criticized during Viollet-le-Duc 's lifetime . Fresh from work in the north of France , he made the error of using slates and restoring the roofs as pointed cones , where local practice was traditionally of tile roofing and low slopes , in a snow-free environment .