Heritage buildings should have Lime pointing, which is a traditional methodology used when the properties were initially built. Lime is a permeable material which allows evaporation of the moisture.
The repointing process requires knowledge and skill to complete successfully. Therefore, achieving the potential of the Lime product. Due to modern materials available, many misunderstand traditional products and treat lime as they would do Cement – or even ADD cement to the mix!
Unfortunately, as with many product markets, there are unsuitable Lime products available. Studies have shown that Hot Mixed Lime (Also known as Quick Lime) is the truest form of Limework.
We do advocate that cementitious pointing (or render) upon heritage properties – rather than use of lime – is unacceptable. Cement traps moisture within the wall which then causes it to penetrate through the masonry itself, therefore causing damage to the stone or brick. This creates dampness internally which may be one of the first signs.
As cement sets hard, that too can damage masonry and cracks can appear as the hardened mortar cracks which allows rain water to penetrate internally. Cement based render can also perform in a similar way.
We will assess each building upon its requirements and circumstances of you the Custodian. Previously we have pointed homes in phases of each elevation. This maybe for priority, co-ordination or to suit financial budgets.
We appreciate that only a patch of repointing may be required for short term maintenance rather than a full elevation. Moreover, that tight joints (such as ashlar) should be grouted with Lime. Due to the fragility of the product, lime should only be used at mild times of the year (i.e. not Winter) and requires careful considerations whilst setting.
Lime mortar will last for a significant time if correctly applied by experienced and skilled persons.