As mentioned earlier, the ideal solution to the problem of driving rain in older buildings is a rendering system that is both waterproof and breathable.
The technology of a traditional rendering system that fulfills both of these criteria originates from ancient Rome. Being outstanding architects and builders, the Romans have discovered that by adding volcanic soils and other minerals to lime, they can significantly alter its properties, especially its mechanical strength and water resistance, while retaining its breathability.
These are different from today’s NHL mortars, whose much higher firing temperatures (around 1200 °C) impair their breathability.
These lime mortars have stood the test of time, being extensively used by the Romans in very demanding environments including sewers, ports, spas and aqueducts. They have also been widely used in Venice, well suited to the humid and aggressive environment of the Venetian lagoon.
For a long-lasting, building-friendly breathable rendering solution, the following rendering schedule is recommended:
1. RINZAFFO MGN lime base coat [10 mm thickness]
Rinzaffo MGN is a microporous breathable lime waterproof and salt-resistant base coat. Its main role is to stop rainwater penetrating into the underlying wall fabric, keeping the underlying walls fabric dry.
Rinzaffo’s internal pore structural is formulated in a way to stop (larger) liquid water molecules, while letting (smaller) water vapours molecules through, facilitating evaporation.
As you can see, the Rinzaffo base coat has a dark color given by its natural prime materials, but that's not a problem as it will be covered up by the main coat.
2. SANACOLOR 2000 MGN main coat [20 mm thickness]
Sanacolor 2000 MGN is a traditional macroporous lime plaster that promotes the continuous evaporation of humidity present in the masonry, keeping surfaces dry and aesthetically pleasing.
It comes in a range of 24 colors. In addition to white, there are light pastel and vivid Mediterranean color options, mass colored with natural earth pigments that are UV resistant and do not fade.
Here are some examples of the final look of some of these buildings:
Main Benefits of the MGN Lime Rendering System
- Tried-and-tested traditional Roman rendering technology
- Simple application: premixed formula, just add water
- No repainting necessary, the render being colored throughout with natural earth pigments
- Does not fade or change its color over time
- Ages beautifully, giving a patina to the building
- A lime system with no cement content or chemical additives whatsoever
- Extremely high quality certified raw materials
- Suitable for the most demanding conservation jobs