The oast was a kiln, with a plenum chamber fired by charcoal at ground floor and the drying floor directly above. The steep pitched roof channelled the hot air through the hops to the top. A cowl on the top of the roof allowed the hot air ('reek') to be drawn up through the kiln in a vacuum effect. The cowl pivoted to control the air extraction and stop rain getting in.
The stowage, was the barn section, it had a cooling floor and press at first floor and storage area at ground floor. The dried hops were taken from the drying floor to cool and be packed using a hop press. The press packed hops in a large sack called a 'pocket' suspended to the ground floor where the pockets were stored to await collection.
Many oast houses were demolished after the hop industry decline at the beginning of the 1900s, however there are estimated to be over of 3500 original cowl ventilated Oast Houses left standing in England, dating from the 1740's to the 1930's.
The majority of oast houses are found in the South East in Kent (approx 65%) and Sussex (approx 20%).
A large number are found Herefordshire and Worcestershire (approx 10%)
there are also a small numbers in…
Hampshire (approx 2%)
…and Greater London
Oast House grid square coverage map © Copyright 2008 nearby.org.uk/Barry Hunter
Hop picking was at its peak in England between 1860 and 1880 when around 70,000 acres of hops were picked each year. Cheap imports from Europe being the main reason for their decline. Nowadays only about 5% of hops are produced compared with the peak years.
The Internal kiln Mid to late c18
Originally oast houses were adapted barns, with a kiln built in the centre. Built of timber, many burnt down, or were replaced with purpose built oasts. The earliest remaining oast is from about 1740, but there were undoubtedly older incarnations that have since disappeared.
The Square kiln Late c18 to early c19.
Fires were common place in the original internal kiln, so the kiln moved outside of the building. They were around 12-14 foot across.
The Round kiln Early c19 to 1920's.
The most common; around 65% of oast kilns are round. It was thought that round kilns were more efficient that the square in terms of heat dissipation, and more cost efficient in materials. Early kilns 12-14 foot, later kilns 16-20 foot.
Mid-late c19 to 1928.
By the end of the 19th Century it was found that circular kilns were no more efficient than square kilns. The square kiln was continued, this time in larger 16-20 foot sizes in response to the large demand for hops, and economy of scale. It was down to the preference of the farmer or architect whether they chose a square or round kiln. There are many round-kilned oast houses with additional square kilns added. Large square oasts are particularly prevalent in East Kent as by the latter part of the hop producing years East Kent was a large driving force of the industry, as there were a number of local breweries, and many newer and larger oasts were built here.
Some purpose built mid c20 oasts also reintroduced cowl ventilated internal kilns, this time using a forced draught system.
The Ridge ventilated kiln. Internal kiln or kilns, this time with a vent running along the top of the roof and mechanical draught. Found on modern oasts c20 to present.
An octagonal kiln can be found in Hawkhurst.
A kiln attached to the oast house at Littlebourne Green was built to fit in with the river.
What is the difference between an Oast House and Malthouse?
As maltings have similar kilns with roof ventilators akin to the oast houses, it can sometimes be difficult to tell if a building was an oast house or maltings. Malthouses were used to dry grain rather than hops, and typically have much larger kiln sizes. The malthouse was part of the brewery and so was significantly larger than a typical oast house. Instead of a rotating cowl they often have a square ventilator cap at the top of the kiln roof. Generally speaking those buildings outside of the South East and The West midlands are Maltings or Malthouses.
There are many malthouses within the British Isles, and like oast houses, most that survive have now been converted to dwellings, usually multiple apartment units, or due to their large sizes and relatively flexible open plan layout, are particularly suited to business units.
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