Historic


Conservation of earth buildings in the UK

Traditionally earth has been perceived as a ‘difficult’ material and one that in inherently complex to conserve. This perception is incorrect; moreover regular maintenance of earth using traditional materials and techniques ensures the longevity and survival of earth buildings. Commonsense approaches to earth buildings and sites demand attention to maintaining, roofs, gutters and downpipes, wall bases and surfaces, a key element is allowing the building to breath as such harder cement-based renders should be avoided in maintenance and conservation work. The adage ‘a good hat and boots,’ is important for earth buildings in the UK.

There is no one ‘easy fix’ in developing conservation approaches to sites and buildings as all conservation approaches are specific to the type of structure, its current condition and an understanding of the building materials, design and form, and changes in use through time. This understanding is vital to enable ongoing maintenance and conservation of historic buildings. It is the long-term aim of EBUK to provide directories of relevant conservation professionals and earth building practitioners.

 Case studies

1. Logie Schoolhouse

The Old Schoolhouse at Logie in Angus, is an 18th century building made of mudwall, the Scottish term for cob. Saved from demolition, it was restored as a new home through the National Trust for Scotland in 2009. Grade ‘A’ Listed as a rare example of vernacular earth construction; much of the original construction survived, though many walls were in danger of collapse because of water ingress.

Mud masons Little & Davie  worked with local contractors to reinstate the building’s historic character, while ensuring a modern quality of facilities. Earth from collapsed walls was saved and mixed with new clay dug from a neighbouring field to make earth blocks and mortar for the repairs. During the repairs, a number of masterclasses and workshops were held for professionals, local people and children to increase appreciation of this strong local tradition.

Arc Architects were lead consultants for the project. The project won 7 awards including the prestigious Europa Nostra Prize, the European Union Prize for Cultural Heritage and a Terra Incognita award.

Earth wall repair at Logie schoolhouse
Completed Logie schoolhouse

2. Clay Mortared Chapels

As part of a landscape heritage project on the Scottish island of Bute, the ruins of two 8th C. Christian chapels and  a medieval castle were conserved with clay mortar. The original structures were built of stone rubble with clay mortar and the island was scoured for materials that could be used to make a repair mortar that would match.

The ruins were in a very vulnerable condition and a huge quantity of clay mortar was used to stabilise the structures, before the wallheads were capped with turf to protect them from rain. The project demonstrated  how durable earth mortared structures can prove, even in exposed locations, and helped develop appropriate techniques for recording and consolidating such ruins with minimal disturbance.

Arc Architects oversaw the project, working closely with mud masons Little & Davie, Historic Scotland and the local archaeologist.

Resotration on the Isle of Bute

3. Moirlanich Longhouse

This is a rare surviving example of a cruck-framed longhouse and archaeological -grade thatch beneath later corrugated iron sheets, located at Killin in the Scottish highlands. .Inside the building has box beds and a paper mache hanging lum in the house, which connects directly to the byre.

While on site to repair the roof, Arc realised that the walls were  clay mortared and in urgent need of consolidation. The original mortar was very weak and  a new mortar was made using clay of a similar colour, but much greater strength. The repaired masonry was pointed with lime mortar and limewashed  on the principal façade.

 

Conservation of Moirlanich Longhouse

Further information introducing conservation approaches can be found via the Society for the Protection of Ancient Buildings website. http://www.spab.org.uk/advice/technical-q-as/

Key to all conservation approaches is the retention of building craft skills and the training of future practitioners in heritage building crafts.

Further reading on UK conservation issues

Ashurst, J and Ashurst, N. 1988. Practical Building Conservation Volume 2. Brick, Terracotta and Earth. English Heritage Technical Handbook. London: English Heritage.

Blaylock, S. 2004. Bowhill – the archaeological study of a building under repair in Exeter, Devon, 1977-95. Swindon: English Heritage.

Brunskill, R. 1981. Traditional Buildings of Britain: an introduction to vernacular architecture. London: Orion.

Campbell, J and Pryce, W. 2003. Brick: a world history. London: Thames and Hudson.

Egeland, P. 1988. Cob and Thatch. Exeter: Devon Books.

Fielden, B. 1994. Conservation of Historic Buildings. London: Butterworth-Heineman.

Houben, H and Guillaud, H. 1994. Earth Conservation. A comprehensive guide. London: Intermediate Technology Publications.

Hughes, R. 1983. Techniques and Materials: Material and Structural Behaviour of Soil Constructed Walls. Monumentum, 26, No 3. September 1983. 175-188.

Hurd, J and Gourley, B. 2000. Terra Britannica: a celebration of earthen structures in Great Britain and Ireland. London: James and James.

Jaggard, W. 1921. Experimental Cottages. A report on the work of the Department at Amesbury, Wiltshire. HMSO: Department of Scientific and Agricultural Research.

Oliver, P. 2003. Dwellings. The Vernacular House World Wide. London: Phaidon Press.

Pearson, G. 1992. Conservation of Chalk and Clay Buildings. London: Donhead.

Swenarton, M. 2003. Rammed earth revival: technological innovation and government policy in Britain, 1905-1925. Construction History Vol. 19. 2003. 107-126.

Walker, B and McGregor, C. 1996a. The Hebridean Blackhouse a guide to materials, construction and maintenance. Historic Scotland Technical Advice Note 5. Edinburgh: Historic Scotland.

Walker, B and McGregor, C. 1996b. Earth Structures and Construction in Scotland. Historic Scotland Technical Advice Note 6. Edinburgh: Historic Scotland.

Warren, J. 1993. Earthen Architecture. ICOMOS.

Warren, J. 1999. Conservation of Earth Structures. London: Butterworth-Heinemann.

Weismann, A and Bryce, K. 2006. Building with Cob. Foxhole, Devon: Green Books.

Williams-Ellis, C. 1920 Cottage Building in Cob, Pisé, Chalk, and Clay, a renaissance London: Country Life.

This list is by no means complete but aims to point you in the right direction!

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