 The hip roof, shallower than its predecessors, was adopted, and roofing slates of thin, handcut limestone slabs replaced shingles.These slates were slightly over an inch thick, and ten to twelve inches (305 mm) long; laid over a cedar frame in an overlapping pattern, they gave a down-stepped appearance.Finally, the roofs were coated with a mixture of lime, sand and water and, when available, turtle and whale oil to provide extra weather-proofing.