The chimney crown, which can also be referred to as a chimney wash, is a large slab that covers the top opening of the chimney. Unlike a chimney cap, which is typically made of metal and merely covers the opening to the flue, the chimney crown covers the entire top of the chimney. Chimney crowns may be made of metal, concrete, or stone. However, they should never be constructed using bricks and mortar, as these materials are not water proof and will deteriorate quickly when exposed to the elements.