Please find sample guide sheets and videos for a variety of renovation tasks on the links below:
- Lime Rendering (external)
- Lime Plastering (internal)
- Lime plastering onto Lath
- Pointing with Lime Mortar
- Tadelakt Application and Maintenance
- Venetian Polished Plaster
The guide sheets cover a wide range of circumstances so please contact us for more detailed advice for your own project. Some background information appears below.
Our advice and information are given in good faith. We guarantee the consistent quality of our products but it is important that users satisfy themselves that they have chosen an appropriate mix and have a suitably skilled workforce.
Benefits of Traditional Materials.
Prior to this century building techniques were very different to those practised today. Traditional buildings benefit in a number of ways from using lime putty based renders and plasters:
- Their porosity allows the structure to breathe.
- Their elasticity helps accommodate general movement.
- Their self-healing nature reduces cracking problems.
- Stone masonry pointed with lime mortar allows moisture to evaporate from the joints rather than penetrate the masonry.
- A breathable paint finish aids evaporation of moisture from a render or plaster.
On the other hand the cement-rich repairs used by many general builders are often very damaging to the structure resulting in:
- A tendency to crack rather than absorb movement.
- Water entering the structure via cracks and then being trapped, creating damp conditions.
- A tendency for renders to separate from the wall, increasing dampness.
- Cob walls can progressively deform and can fail.
These problems are often compounded by the use of modern acrylic paints which trap moisture in the walls.
When specifying a lime mortar, consider:
- Purpose – bedding, pointing, rendering, plastering – and their different requirements.
- The nature of the substrate – its strength, durability, porosity, water vapour permeability.
- The environmental conditions to which substrate and mortar are exposed.
- The need to match existing mortars.
Pure limes are only set by carbonation where the lime (calcium hydroxide) reacts with carbon dioxide from the air to form calcium carbonates.
Mortars and plasters based on pure limes are suitable for internal work or sheltered conditions where hydraulicity and frost resistance are not necessary. They offer maximum breathability and their lower compressive strengths can be an advantage in accommodating stress and movement.
From the times of the Romans, lime mortars for building or external rendering had added ingredients to increase their compressive strength, improve frost resistance and allow them to set under water. The latter lime mortars are called hydraulic for this ability to set under or in the presence of water. The degree of hydaulicity of the mortar will affect many of its characteristics e.g. compressive strength, speed of set in the presence of water, water vapour permeability.