Lime has been used in building for thousands of years, at least as far back as Roman times.
It is a calcium-containing material that is extracted from limestone. You can still see many of the old lime kilns where this was done, dotted around the countryside.
In very simple terms, the characteristic that makes lime so useful is that it takes a form which can be mixed with other materials such as sand, to form a workable substance which can be manipulated. However over time it reacts with carbon dioxide and partially reverts to limestone, forming a hard material. Despite their hardness, lime based building materials remain “breathable” i.e. they allow moisture in the form of water vapour to pass through them. This is vital for old buildings to remain healthy and free from damp.
Lime mortar is lime is mixed with an aggregate, typically sand. Lime plasters have a finer aggregate and may also have animal hair added. Limewash is lime mixed with water and possibly a pigment.
Lime mortar is used to point the joints between bricks or stones. Lime plasters and lime washes are traditionally used on the walls of old buildings. All these materials have the great advantage that they are breathable.
With the introduction of portland cement in the middle of the nineteenth century, the use of lime began to decline, and by the middle of the twentieth century, lime was barely used in construction. Cement seemed like the better material, being quick-setting, easy to use and very strong.
Unfortunately, it started to become apparent in the 1970s that the cement had some major drawbacks (see the pages on breathability and damp), and lime has gradually been making a come-back. Unfortunately, most builders are not trained to work with lime and find it difficult and awkward compared to cement.
We are specialists in working with lime and we love to see the restoration of damp, sick old buildings to their former glory through the use of this marvellous material!