Lime kilns

A limekiln is an industrial structure used for burning limestone, chalk, or in the case of medieval Colchester, oyster shells to make quicklime and generally comprising a circular, square or rectangular pit, usually between 1 and 5m in diameter and up to 3m in depth, in which the lime was fired using timber, charcoal or coal as fuel. At the base of the pit there are often one or more drawholes or stokeholes, through which the fire was lit, fed, and the ashes and lime extracted.

Limekilns were first used in Britain in the Roman period; following this there was little demand for mortar until the medieval period with the building of churches, religious houses and fortifications. There is documentary evidence that lime was used in the Anglo-Saxon period and at Great Paxton, Cambs, the bases of two limekilns were found c270m from an Anglo-Saxon church. Limekilns were in use throughout the whole of the medieval period; those that have been excavated in Southampton date from the 11th century to the late 15th or early 16th century. In the medieval period limekilns were predominantly used for the production of mortar for building purposes; occasionally they were used for the production of lime for agricultural purposes, as they were to a great extent in the 18th and 19th centuries. Post-medieval limekilns tend to be structurally more sophisticated than those of the medieval period.

Since the demand for mortar in the medieval period was widespread, limekilns are found in all parts of the country, with no distinct regional concentrations. Concentrations do occur in urban areas in the medieval period where the demand was greatest. One sixteenth century limekiln is known at Taplow in Buckinghamshire. However, lime kilns are mainly rural in later periods when they were producing fertiliser for crops, such as at Wycombe Heath.