Part of Historic Environment Scotland

Mortars, Plasters and Renders 2

Dates: TBC
Days of the week: TBC
Total hours: TBC
Taught hours: TBC
On-site instruction: TBC
Off-site instruction: TBC


Take a closer look at the various functions of limes and other cementing binders in mortars, plasters and renders used in traditional Scottish buildings.

Limes and other cementing binders are used in mortars, plasters, renders, harling, limewash and plastic repairs for a range of purposes. Explore their technical requirements and the development and use of mortars, plasters and renders over the 19th and 20th centuries.

This module will focus heavily on the specification process and give you the ability to assess all relevant aspects of a site, including exposure levels, substrate condition and type. Learn how to recognise failure mechanisms and understand how mortars, plasters and renders should be safely worked.

You will receive detailed instruction in how to apply mortars, plasters, renders and traditional harling, including substrate preparation and aftercare.

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

  • Mortars in Construction
  • Mortar Conservation Issues 1
  • Mortar Conservation Issues 2
  • Mortars – Site Work and Health and Safety Issues
  • Historic Use of Plasters
  • Historic Use of Renders and Harling
  • Plaster Conservation and Repair
  • Renders and Harling – Conservation and Repair 2
  • Plasters, Renders and Harling – Site Work

Potential site visits

  • Great Hall, Stirling Castle
  • Scottish Lime Centre and Charlestown kilns
  • Plaster contractors’ workshops
  • Craigievar Castle
  • Kellie Castle
  • Glamis Castle
  • City Heritage Trust sites
  • Conservation Area Regeneration Scheme sites
  • Townscape Heritage Initiative sites
  • Historic Environment Scotland estate schemes


Mortars in construction

  • Purposes of traditional mortars, plasters and renders – e.g. weatherproofing, insulation, movement, appearance
  • Range of uses – e.g. bedding, pointing
  • Types of joints – e.g. flush, struck, slaister

Origins of limes, cement and clays and their use in the Scottish tradition

  • Sources of materials
  • Geological and mineralogical characteristics of limes and clays – e.g. porosity, permeability
  • Gauging with gypsum and other additives
  • Historic background and development of traditional practices – from early decorative lime plaster to mechanisation in the 20th century

Plaster and render application

  • Hand-modelling of early lime stucco
  • Plain or flat plasterwork, running of mouldings, application of cast embellishments
  • Mass production of large cast sections of fibrous plaster and requisite timber supports
  • Importance of sound substrate
  • Correct detailing

Conservation and repair

  • Survey, inspection and diagnosis of decay, deterioration and damage
  • Type of damage – from cracking and crazing to moisture ingress and mechanical damage
  • Removal of decayed or damaged coatings
  • Preparation of substrates or supports
  • Replicating moulding profiles or applied cast ornamentation
  • Sustainable sourcing of matching binders and aggregates
  • Paint removal
  • Application of air permeable paints or limewash