Traditionally buildings were constructed and decorated using lime based products instead of cement. Lime was used for example in mortars, plasters, renders and masonry paints.
Buildings originally built using lime based products, which as a general rule is all buildings constructed before 1900, must be repaired with lime.
Significant problems can arise when cement is introduced to buildings originally constructed and previously maintained using lime. It can cause permanent damage to the buildings historic fabric, as well as being visually unsympathetic.
Lime is softer, more flexible and much more ‘breathable' than cement. Cement mortar for example acts like a glue, does not move with the building and prevents the evaporation of moisture from the joint.
Likewise, a cement render would prevent the evaporation of moisture from the building. Cement is hard and brittle, and is prone to cracking which allows water into the structure, which can then seep into the interior.
Failure to use lime in traditional buildings often results in the surface of brickwork and stonework failing, becoming crumbly or powdery as trapped moisture causes erosion and can cause rising damp.
Historic Scotland has published guidance on the use of lime and cement in traditional buildings which can be downloaded below.
If you are unable to view documents of these types, our downloads page provides links to viewing software.