Oast House is a building designed for drying hops before they are compressed, baled or pelletized, packaged, and sold to brewers. Despite a recent fashion for “fresh hop” or “harvest” beers, almost all hops are dried before use. The hop flower contains plenty of moisture, and like most flowers it will turn brown and rot if not properly dried. Oast houses, or “hop kilns” as they are also known, can come in many forms; today, hop drying tends to be industrial and mechanized. But to most people—especially in southern England—the name conjures a specific image of a tall, round building with a distinctive white cone on top, and a cowl and weather vane at its peak.
Oasts traditionally used a wooden fire to dry hops, followed by charcoal, and most recently, oil. The tall cones of the buildings were designed to create a good draught for the fire, and the cowl and vane enabled the roof to turn into the wind to get the best airflow.
Hops would be spread in a layer on a latticed floor of wood and wire, allowing the hot air for the fire below to pass through them. After drying, the hops were then compressed into bales and loaded into hessian sacks known as “pockets.”
Hops became popular in England in the 15th century and the earliest description of an oast house dates back to 1574. The oldest surviving example is at Cranbrook near Tunbridge Wells, Kent, and was built around 1750. Perhaps not surprisingly, over the centuries a great many oast houses were consumed by fires. Dried hops are easily flammable and once they caught fire, the design of the building could quickly turn it into a furnace.
With mechanization the traditional oast house became obsolete, but the structures are still a common site around Kent, the “hop garden of England.” Many of them have been converted for residential use and are quirky, highly sought-after homes.