What are they & Why use them?
For at least 5,000 years, lime has been the principal material used when binding together aggregate to make plasters and mortars.
It is manufactured by firing limestone in a kiln, driving off the CO2 and water. This produces ‘quicklime’ which is then ‘slaked’ (the water is added back). The resulting material is a lime binder, either hydraulic (reacts when water is added, then absorbs CO2) or non-hydraulic (only sets by absorption of CO2). Whether the lime is hydraulic or non-hydraulic depends on the natural presence of clay and silica inclusions in the limestone.
In the last 100 years the use of lime has almost died out as a binder, replaced by modern alternatives, based on gypsum and Portland cement, the roll of lime in construction reduced to that of an additive to sand and cement mixes to improve workability. These modern binders produce plasters and mortars that are much harder and faster setting.
Whilst these features are advantages to the building contractor, giving a far greater control over the programme of works, it is now understood that the use of these materials has a very damaging effect on traditional properties.
A word commonly used with historic buildings is breathability, this is the ability of the building to allow free transport of water as a vapour through the fabric of the walls. This reduces the levels of internal condensation and improves the quality of life for the inhabitants.
But there’s so much more….
Reducing the moisture levels in the walls greatly improves the thermal efficiency of the building, less damp, less heat loss, less energy used to keep warm. Lower heating bills!
If the walls of your building are timber, the use of modern plasters and renders will quickly increase the moisture levels to the point where insects and fungus can thrive, causing rapid and very expensive decay.
Many traditional, timber framed buildings that have stood for 500 years or more, have been subject to catastrophic and irreversible damage in less than the last 50 years.
If you care about the environment, the production of lime involves much cooler temperatures than that of cement, less energy is used, so a much reduced carbon footprint. Add to this the fact that lime re-absorbs carbon dioxide when curing and the overall environmental impact of your building is greatly reduced.
At DGS Plastering, we understand the importance of using the right materials for the job, we work closely with suppliers to make sure that products used not only fit the client’s aesthetic and budget requirements, but are appropriate to the age, style and type of building. We are also able to advise on the correct paints to finish the project.
We are proud to be on the Best of Lime exclusive list of ‘highly recommended’ contractors.!