by Gethin Harvey
Since the last post, the Scholars have headed north to Cumbria and into Scotland to study the effect of changing geology and wetter climates on vernacular buildings and the accompanying variations in construction techniques.
In such areas the detrimental effects of water ingress and damp can be exacerbated if not addressed; with increases in average annual rainfall over recent years, it also poses questions on how well equipped historic buildings are to deal with the amount of rainfall seen today and associated repair philosophies.
One vernacular tradition is the construction of buildings with solid earth wall structures which go by different names dependent on the regional variations in construction and local dialect. These are known locally in Cumbria as ‘clay dabbins’ and following a guided tour of Burgh by Sands by 2014 fellow Alex Gibbons it became apparent that they are often difficult to spot, hidden behind protective lime renders.
This not only leads to uncertainty in the exact amount surviving in the UK it also means that they may often not have the statutory protection they deserve. We subsequently joined local craftspeople and volunteers to progress the construction of a newbuild clay dabbin building in the RSPB sanctuary on the Solway Plain. The experience of working with the material revealed the practicalities which determine the methodology of construction; the walls are formed of lifts only a few inches in height, contrasting with, for instance, cob buildings in Devon where the drier material allows lifts of up to 2 ft. It was a great example of how traditional crafts may be used to provide sustainable opportunities for building using nothing outside the immediate context of a site. Surviving examples serve as great precedents for this and their maintenance is crucial, one of many topics which will be covered at Clay Fest 2016 which will provide opportunities for further explanation and hands-on experience at the RSPB Campfield Marsh Reserve in Bowness-on-Solway, Cumbria on 18 – 23 July 2016.
For more information please see the Earth Buildings UK website.
Scottish Working Party
Despite predictions of thunderstorms, the weather was glorious (with a minor exception – the typically soggy British BBQ on the final evening).
The weather enabled the volunteers to throw themselves into the work at Balmerino Abbey, a ruinous masonry structure in Fife. This included raking out cement pointing in a boundary wall and repointing with lime mortar; soft capping trials and preparing the materials for repointing and soft capping.
Lime has been a constant theme throughout our visits and it was a great asset to have Bill Revie, Andy Bradley and Duncan Strachan from the British Limes Forum to guide us. For the lime pointing a hybrid mix of quicklime gauged with NHL 5 was used with local sharp sand. This was a combination we had not previously seen and was designed to provide an initial chemical set to prevent the mortar being damaged by frost and/or wind before carbonation. Their interactive demonstration of the lime cycle and the ‘3-minute kiln’ (for construction, not burning!) was of great benefit to all present and provided us with a better understanding of its use in more severe climates.
With a similar range of repair methods as those proposed for the SPAB England Working Party which will be held at Greatham, Hampshire on 3 – 9 July 2016, it was great to have the experience of Alison Davie Construction Ltd to supervise the works. Aside from the practical experience it was a brilliant social meeting with many partaking in their first official ceilidh and we would like to convey our thanks to Historic Environment Scotland and National Trust for Scotland and all others involved in an incredible few days.