Value assessment of stonecleaning

This research has been published as: Laing, R.A. 1999, "Stone cleaning: A value assessment", PhD Thesis, The Robert Gordon University, Aberdeen.

This work continues research in the field of conservation of building stone by the Masonry Conservation Research Group, at the Robert Gordon University which, over the past 3-4 years, has been concerned with the effects of stonecleaning on building sandstones - (Webster et al. 1992) - and is now continuing with an analysis of the effects of stonecleaning on granite facades. The proposal presented here, whilst forming part of the granite project, is aimed at investigating, within the context of value, the overall effect of stonecleaning on the built heritage of Scotland, including both sandstone and granite buildings. This research was funded by Historic Scotland and The Robert Gordon University.

For many years now, stonecleaning has been carried out on much of Scotland's built heritage, and concern is now being shown that the effects of such activity have not all been desirable (Perks 1990, Webster et al. 1992). Where certain changes have been to the good of the buildings concerned, many feel that, in certain circumstances, the buildings have been damaged in such a way that either the stone itself is left prone to accelerated decay, or the environment in which it is situated is damaged aesthetically as a result.

The effect which stonecleaning has on the economic value of a property, and also on long-term life cycle costs, has not been effectively investigated in the past. Stonecleaning has often been carried out for reasons giving only short-term gains in "value", and which do not take into account the effect on long-term maintenance and repair costs. As poorly implemented stonecleaning may damage the stone, or lead to an increased rate of decay (Ireson 1987, Sowden 1990, Perks 1990), as thin surface layers may be removed during the cleaning process, the incidence of stone repair may well be similarly affected. The associated indirect costs, such as Architect's fees, and contractor's expenses, may well be considerable, making the thorough investigation of a stone facade, prior to stonecleaning work being carried out, desirable.

Through the rigorous analysis of the value implications of stonecleaning, it is possible to develop a truer picture of the wider implications of such work.