Soft Capping in Scotland: The context and potential of using plants to protect masonry
The purpose of these cappings, which occur on all types of buildings, is to protect the underlying sandstone slabs from delamination, by reducing moisture ingress and flux, as well as exposure to frost. A similar covering of turf applied onto pantiled roofs, to prevent them being lifted by the wind as well as for draft proofing and insulation, is reported in Moray by Walker (2003).
Fig. 4.28: Cleitean, St. Kilda (CS7). The diversity of cappings is not well understood.
Fig. 4.26: Dounby Click Mill, Orkney (CS7). Roof renewed c. 1980 in a relatively sheltered location.
Fig. 4.29: Cleitean, St. Kilda (CS7). The soft cappings sit on a layer of small stones, over large stone slabs.
Fig. 4.27: Eynhallow, Orkney. House abandoned c. 1851, in an exposed location.
The cleitean of St. Kilda (CS7) are another remarkable local tradition. Approximately 1430 cleitean survive in varying conditions, dating from prehistory to the early 20th century. The construction of these structures, which is not fully understood and has little historical record, comprises a mound of soil, varying in thickness from 200mm to 1m, with a turf covering, laid over a flat stone slabbed roof, sometimes mounded with smaller stones, bearing on drystone walls. Stones were often laid on top as a restraint against wind uplift.
Fig. 4.30: Cleitean, St. Kilda (CS7). Progressive collapse of the masonry inevitably follows decay of the soft capping.
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