The Use of `Skailie' in Medieval and Post-Medieval Scotland
Walker, Bruce, Antiquity
The predominant roofing material in Scotland, from the prehistoric period to about 1900, was thatch. This does not mean that there was a single material covering all roofs in the country, but rather that roofs were covered with a range of vegetable materials including seaweeds, straight-stemmed plants such as bracken, dock, iris reeds, rushes, natural grasses and cultivated cereals to woody plants such as broom, juniper and heather. This list is not exhaustive and the final choice was dependant on site location, degree of exposure, roof pitch, local farming practice, local economy, number of helpers available and many other factors. The final choice is not always easy to understand in relation to present-day criteria but the range of thatching materials, methods of application, anchoring devices and so on, was limitless. Gradually, as construction firms began to replace volunteer labour, the range of thatches reduced, but even then there was an extremely wide choice available. Thatch types, surviving into the 20th century, have been studied (Walker et al. 1996) and guidance has been provided for repair and renewal. Many Scottish thatches required periodic resurfacing to ensure their continued performance. This resulted in a stratified accumulation, and by introducing archaeological techniques to the roof covering we have been able to identify changes in the husbandry of the thatching materials over successive decades (Holden et al.: 1998).
Thatching was so common that theik, thak or thatch became a generic term for the application of any roofing material. Other roofing materials were known from Roman times onwards, but only on very high-status buildings, and even as late as the 18th century reference is often made to a building being `thatched with' tile, timber, slate or some other material.
In Scottish high status building reports these new materials were often referred to as scailie, scailyie, scailne or skailie. The spelling is fairly close to scait, sclate or slate and this has caused further confusion, but Imrie & Dunbar (1982) state that scailie refers to a covering of slate, stone, tile or timber, that is, blue slate, grey slate, plain tile or shingle.
Although all of these materials were known and used during the Roman occupation of Britain there is no evidence of any large-scale activity in the production of blue slate, grey slate or plain tile in Scotland until the mid 18th century. Small-scale production is possible; for example, glazed plain tiles dated from the 14th century have recently been excavated by Scottish Urban Archaeology Trust at King Edward Street, Perth. Similar glazed plain tiles were also excavated on the Isle of May, Fife (Heather James pers. comm.). The date of manufacture is not known but a coin dating from the later 13th century was found in the same destruction layer (Will ri.d). Grey slate begins to appear in both building accounts and archaeological excavations in a 17th-century context, but blue slate does not appear until the 18th century.
This leaves shingles as the only scale-like roofing material that could have been produced and used in any quantity without leaving much physical evidence on the environment or in the archaeological record. On most sites shingles would rot in the soil, but in water-logged conditions they might survive.
Other new materials such as lead, copper, paper, iron and zinc were gradually being introduced, but all were costly to produce and most were not available in sheet form until the late Medieval or Post Medieval periods.
The change from thatch outside the Royal circles seems to happen in the 17th century, when entries for a range of roofing materials begin to appear. This coincides with a broadening in the range of archaeological finds. Entries from the forthcoming volume of the Dictionary of the Older Scottish Tongue confirm the trend. Edinburgh is described in 1621 in the following terms (Acts. …