Artificial and recycled slate tiles more eco-friendly than the natural equivalent, and often easier to install, whilst still creating the sought-after appearance of natural slate roofs. Because of the thatched roof's drawbacks, the development of clay roofing tiles was a great advance in building technology. Clay tiles, fired like pottery, were longer lasting and more waterproof than thatch. Old buildings mainly have simple, clay tiles that have been fired in a kiln. Tiled roofs, while once ubiquitous in china, are now used less.