Since so few brickworks have been excavated the overall size of brickworks is difficult to ascertain, but will include the kilns, clamps, buildings, working areas and associated features. Those that have been excavated were small-scale temporary works, and had an area of less than c0.02ha; more permanent brickworks are likely to have been much larger in areal extent. Sites will also be much larger if the clay was extracted on site; at Caistor, for example, clay pits covered an area of c1.6ha.

The most prominent component of any brickworks is the kiln or kilns; although a number of tilekilns have been excavated, as yet there have been no excavations of a medieval brick kiln in this country. Documentary evidence indicating numbers of bricks produced suggest that brick kilns would have been considerably larger than pottery or tile kilns, at Caistor holding around 92,000 bricks, and at Hull holding between 35,000 and 45,000 bricks; two 19th-century kilns of this latter capacity measured 8.1m x 3.3m x 3.75 high, thus that at Caistor may have measured in the region of 10.5m x 5.4m x 3.6 m high (Smith 1985). It is thought that medieval kilns were basically similar to these, and a mid-16th-century illustration from Germany shows a kiln of this type. These kilns were rectangular in plan with openings at each end for loading and unloading the bricks, and low, arched fire-holes along each edge, for the fuel. A 14th-century tile kiln from Boston, which was also used for some brick firing, was similar to this.

Bricks could also be fired in a clamp; unlike the kiln, this was a temporary structure of fired or unfired bricks, within which the bricks for firing were stacked. Channels, or "live-holes", left in the base of the walls, were filled with faggots for igniting; these were then blocked when the clamp was alight. The only brick clamp to have been excavated is that at Boston (Mayes 1965). This comprised a platform of hard fired silty clay 15-25cm deep, with maximum dimensions of 6.9m x 4.5m; This was surrounded by a burnt area. It has been suggested that these clamps would have been used by the temporary works set up in connection with a particular building, while the larger, permanent works used kilns (Smith 1985).

Underlying the red fired area of the Boston clamp, and spreading out from it, was a small area of limestone chips rammed to a compact surface; this has been interpreted as a working area.

Excavations of tile kilns have frequently revealed evidence of shelters or buildings probably used as workshops, drying sheds or stores; these would also have been present at brickworks, but due to limited investigation, few traces have been revealed. At Beck View Road, Beverley, where there was a period of brickmaking, there is evidence of two open-sided timber sheds built on padstone supports or postholes, probably used as drying sheds, as well as traces of a more substantial timber building of padstone and sill wall construction, containing two hearths (Youngs et al 1987). Documentary evidence from Hull indicates that there was a structure, the tilehouse, with mud and stud walls, probably used for moulding the bricks and for watching the kilns.

Several sites are indicated in the field by the presence of clay pits from where the clay was obtained, and which were probably located close to the brick-making area; these appear as areas of ponds, pits, and spoil heaps, which are often overgrown and filled with stagnant water. Clay pits have been located at, for example, Edlington Moor, near Tattershall, Lincs, and at Sandown, near Sandwich, Kent.

At the brickworks itself the clay is likely to have been stored in a pit; at Boston a sub-rectangular depression measuring 1.2m x 1.8m and 0.3m deep with sloping sides was probably used for this purpose.

A rectangular brick surface was also revealed at Boston which has been interpreted as the firm foundation of a moulding table, on which the bricks and tiles were moulded; this measured 2.7m x 1.2m and was laid on the natural silt with no trace of mortar or burning.

Once the bricks were moulded they had to be left to dry on a specially prepared area of ground, known as a 'hackstead'. These would have been covered with sand, hay or straw to prevent the stacks of green bricks from sticking to the ground. Documentary evidence refers to these features, and archaeologically at Boston, a hackstead may be represented by a limestone chip floor, although this is contemporary with the tile kiln rather than the brick clamp.

Also associated with the Boston clamp was a deposit of coal and coal-dust which has been interpreted as a fuel dump; this was approximately 0.25m thick and was probably used to mix with the bricks in order that the clamp provided its own materials for combustion.

Ditches for surface drainage may also have been necessary for keeping the site dry, not least because brickworks were often located on wet, clayey ground; two ditches were revealed by excavations at Beck View Road, Beverley, and records at Hull suggest that the site may have been surrounded by a ditch. Ditches may also have been used as a water store for use in the brick-making process.

Reference to a 'tilery gate' suggest that the brickyard at Hull would have been surrounded by a wall, but there is no archaeological evidence of this.

Because very few sites have been extensively excavated, it is difficult for there to be any classification of brickworks using morphological characteristics. Smith (1985), however, has classified them according to the type of brickworks as follows:

A. Permanent/semi-permanent brickworks worked by a corporation, private owner, or leased out (eg. Hull)

B. Temporary brickworks providing bricks for specific projects (eg. Caistor)

Once abandoned, most sites had no secondary or tertiary use, although sometimes, as at Boston, the manufacture of tiles may have continued.

Bricks were used in England during the Roman period after which there little evidence for their manufacture until the 12th century; during the early medieval period Roman bricks were often reused. The early 12th- and 13th-century brickworks were producing bricks for occasional use in churches and sometimes secular buildings, although some may have been imported. By the end of the 14th century, however, the use of brick became more common-place, in use as a prestige material in, for example, palaces, castles, halls, churches etc., and only reaching the level of vernacular building in the 17th century (Smith 1985). Bricks were also used for flooring and in town defences as at York and Beverley in the 14th and 15th centuries. During the medieval period, brickworks were either established for a specific building project and were probably temporary, or were permanent/semi-permanent works which were either municipal works eg. Hull, or which were privately owned. The bricks themselves were usually shaped using a mould to produce a standard-size brick, typically 22.5cm x 10cm x 5cm; bricks made without a mould were often larger (the medieval "Great Bricks").

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