The benefits of traditional lime mortar

Pointing is the material or term used to describe the finish between brickwork or masonry used in the construction of a property. Depending on the age of the building or construction type, the mortar that is used will either be made from lime or cement.

Within Scotland, most traditional granite and sandstone buildings are constructed with lime and finished with a lime pointing. Lime is produced by burning limestone (calcium carbonate or calcite) in a kiln to temperatures in excess of 850 degrees. This drives off the carbon dioxide to produce calcium oxide, which is a highly reactive solid known as ‘quicklime’. Quicklime or hydrated lime (the binder) is mixed with aggregates to produce a mortar and sets with the reaction of both water and air (carbonation).

Cement (or ‘Portland cement’ as it was formally known) is produced in much the same way as lime, but it is burnt at a much higher temperature in the kiln and with the addition of reactive clays. The result is a binder that sets rapidly in the presence of water and sets to a much higher compressive strength than lime.

The development of Portland cement in the early 19th century led to the demise of pure lime mortars in the building trade. Although lime was still commonly used, it tended to be gauged with cement to produce a harder, faster setting mortar. However, over time it was found that cement mortars tended to decay masonry and brickwork due to the inherent incompatibilities of the materials, primarily in terms of flexibility and vapour permeability. This incompatibility of the materials is the primary cause of locked-in damp and capillary action (i.e. the transfer of moisture through walls) and often leads to cracking, which then allows the moisture to get in more rapidly.

The use of traditional lime mortars greatly reduces the risk of these damaging factors impacting your property. Based on our knowledge of traditional granite constructed properties and the use of cement and lime mortars, we only use the highest quality lime mortars in all our pointing works. We also have the ability to send mortars for testing and offer a full colour matching service from a palette of over 400 colours, which will ensure that your lime pointing is not only fully functional but also aesthetically pleasing and in keeping with the look of your property.

To find out more about our lime pointing work and colour matching service, contact us here for a consultation and free estimate.