An oast, oast house (or oasthouse) or hop kiln is a building designed for kilning (drying) hops as part of the brewing process. Oast houses can be found in most hop-growing (and former hop-growing) areas, and are often good examples of agricultural vernacular architecture. Many redundant oast houses have been converted into houses. The names "oast" and "oast house" are used interchangeably in Kent and Sussex, but in Surrey, Hampshire, Herefordshire and Worcestershire they are called "hop kilns". An oast house consists of a rectangular one- or two-storey building (the "stowage") and one or more kilns in which the hops were spread out to be dried by hot air rising from a wood or charcoal fire below. The drying floors were thin and perforated to permit the heat to pass through and escape through a cowl in the roof which turned with the wind. The freshly picked hops from the fields were raked in to dry and then raked out to cool before being bagged up and sent to the brewery. The Kentish dialect word kell was sometimes used for kilns ("The oast has three kells") and sometimes to mean the oast itself ("Take this lunchbox to your father, he's working in the kell"). The word oast itself also means "kiln". The earliest surviving oast house is at Golford, Cranbrook near Tunbridge Wells. It dates from some time in the 17th century and closely mirrors the first documentary evidence on oasts soon after the introduction of hops into England in the mid-16th century. Early oast houses were simply adapted barns, but by the 18th century the distinctive tall buildings with conical roofs had been developed to increase the draught. At first, these were square, but around 1800 roundel kilns were developed in the belief that they were more efficient. Square kilns remained more popular in Herefordshire and Worcestershire and came back into fashion in the southeast in the later 19th century. In the 1930s, the cowls were replaced by louvred openings as electric fans and diesel oil ovens were employed. Nowadays hops are dried industrially and the many oast houses on farms have now been converted into dwellings. One of the best-preserved oast house complexes is at the Hop Farm Country Park at Beltring.
Hop drying
The purpose of an oast is to dry hops. This is achieved by the use of a flow of heated air through the kiln, rather than a firing process. Hops were picked in the hop gardens by gangs of pickers, who worked on a piece work basis and earned a fixed rate per bushel. The green hops were put into large hessian sacks called pokes (in Kent) or green sacks (West Midlands). These would be taken to the oast and brought into the stowage at first floor level. Some oasts had a man-powered hoist for this purpose, consisting of a pulley of some 5 feet (1.52 m) diameter on an axle to which a rope or chain was attached. The green hops when freshly picked had a moisture content of approximately 80%. This needed to be reduced to 6%, although the moisture content would subsequently rise to 10% during storage. The green hops were spread out in the kilns. The floors were generally of 1+1⁄4-inch (32 mm) square battens nailed at right angles across the joists, placed so that there was a similar gap between each batten, and covered with a horsehair cloth. The hops would be spread some 12 inches (300 mm) deep, the kiln doors closed and the furnace lit. When the hops were judged to be dried, the furnace would be extinguished and the hops removed from the kiln using a scuppet, which was a large wooden framed shovel with a hessian base. The hops would be spread out on the stowage floor to cool, and would then be pressed into large jute sacks called pockets with a hop press. Each pocket contained the produce of about 150 imperial bushels (5,500 L) of green hops. It weighed a hundredweight and a quarter (140 pounds (64 kg)) and was marked with the grower's details, this being required under The Hop (Prevention of Fraud) Act, 1866. The pockets were then sent to market, where the brewers would buy them and use the dried hops in the beer-making process to add flavour and act as a preservative. Oasts sometimes caught fire, the damage sometimes being confined to the kilns (Castle Farm, Hadlow), or sometimes leading to the complete destruction of the oast (Stilstead Farm, East Peckham in September 1983, and Parsonage Farm, Bekesbourne in August 1996).
Early oasts The earliest description of an oast dates from 1574. It was a small building of 18 feet (5.49 m) by 9 feet (2.74 m) in plan, with walls 9 feet (2.74 m) high. The central furnace was some 6 feet (1.83 m) long, 2 feet 6 inches (760 mm) high and 13 inches (330 mm) internal width. The upper floor was the drying floor, and only some 5 feet (1.52 m) above the ground floor, hops being laid directly on the slatted floor rather than being laid on hessian cloth as was the later practice.
Conversions to oasts
In many cases, early oasts were adapted from barns or cottages. In 1779, St. Peter's Chapel, Frindsbury was converted to an oast. A chapel at Horton, near Canterbury was also converted. Part of Hastings Priory was serving as an oast in 1823. The gatehouse to the Bishop's Palace, Bosbury, Herefordshire was also converted. This was done by building a kiln within the building, dividing it into three, the upper floor being used to receive the "green" hops, dry them and press the dried hops. Examples of this type of conversion can be seen at Catt's place, Paddock Wood, and Great Dixter, Northiam. Later conversions of barns and cottages would be by either building an integral kiln within one end of the building, as seen at Biddenden, Kent, or by adding kilns externally to the existing building, as seen at Barnhill Farm, Hunton, and also at Sutton Valence, or both, as seen at Ightham Mote.
Purpose-built (custom) oasts
An agreement for the building of an oast in Flimwell in East Sussex in 1667 gave the size of the building as 30 by 15 feet (9.1 by 4.6 m) and another to be built there was to be built in 1671 being 32 by 16 feet (9.8 by 4.9 m) or 17 feet (5.2 m), having two kilns. The earliest surviving purpose-built oast is at Golford, Cranbrook, built in 1750. This small timber framed oast is 21 by 15 feet (6.4 by 4.6 m) in plan, and has a hipped tiled roof. It has one kiln, and a single cowl on the ridge of the roof.
Traditional oasts
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