Part of Historic Environment Scotland

Unfired Earth Conservation

Dates: 29/11/18
Days of the week: Thursday, Friday
Total hours: 52
Taught hours: 18.5
On-site instruction: 10
Off-site instruction: 12


Study the use of unfired earth construction in Scotland’s historic built environment, a practice with ancient and obscure origins.

Various vernacular Scottish buildings feature walls, floors and coatings made of unfired earth, turf and clays, and a key focus is their use alongside timber, thatch and other local materials. You will examine the nature of building clays and associated earth or turf products, their material characteristics and known sources.

Weathering and decay processes and the effects of man-made wear or damage are studied. You will touch on repair and restoration techniques using traditional and modern tools, and follow the full life cycle of a repair project – from survey and diagnosis to on-site installation. Conservation repair principles are an important area of discussion throughout.

Entry requirements

Individual modules are open to anyone with an interest in the subject matter. Applicants for the Advanced Professional Diploma should have a relevant degree or professional experience.

Classes, lectures and presentations

  • Origins and Traditions
  • Unfired Earth in Construction
  • Unfired Earth – Decay and Conservation
  • Repair Techniques 1
  • Repair Techniques 2
  • Repair Techniques 3

Potential site visits

  • Cottown Schoolhouse, St Madoes
  • Logie Schoolhouse, Tain
  • Highland Folk Museum, Newtonmore
  • Corse Croft, Kinnour
  • Fort George


Origins of the material and Scottish traditions

  • History and range of use in Scotland, including regional variations
  • Material considerations – from clay and turf types, and their use with other materials, to the strengths and weaknesses of earth and clay

Unfired earth in construction

  • Clay as an earthen mortar mix
  • Clay as a waterproofing agent
  • Mudwall – with and without masonry, brick or other facings
  • Clay or earth blocks
  • Mass or rammed earth construction (pisé) – with and without shuttering or formwork
  • Internal use – e.g. partitions, clay plasters
  • Recognising earthen/clay mortars and plasters
  • Turf construction (e.g. fale, divet) and earthen cores
  • Colouring agents

Decay mechanisms and conservation issues

  • Structural failure and other issues
  • Water erosion/ingress
  • Vegetation
  • Infestation by rodents, insects and other pests
  • Abrasion and mechanical damage
  • Inappropriate past repairs or treatments

Repair and conservation

  • Establishing the correct approach – repair or renew?
  • Protective coverings – permeable renders and plasters
  • Establishing construction techniques
  • Evaluating soils/clays – e.g. particle size, binders
  • Sourcing matching material – and the importance of documentation
  • Site practice – including tools and equipment, and work sequence
  • Renewal of footings
  • Reinforcement of walls
  • Cutting out and piecing in with matching material
  • Stitching, bonding and grouting
  • Importance of reversibility of repairs/alterations
  • Health and safety issues