Greening is a natural phenomenon of algae and moss growth that has existed for as long as life has existed on our planet. Any material, including inorganic materials, exposed to the outside world, is eventually colonised by algae-like micro-organisms. Until a few decades ago, this phenomenon was hardly noticed because it took several years to manifest itself. Human action over the last few decades has significantly modified several environmental conditions in a way that is unfortunately favourable to greening:
- increased sources of atmospheric carbon feed via pollution (combustion gases and industrial gaseous/particulate emissions: soot and volatile organic compounds)
- increased sources of atmospheric nitrogenous nutrients through the intensive use of nitrogenous fertilisers, especially in rural areas.
There are also accelerating conditions: the exposure of your house to the wind, a lack of ventilation in front of the tiles, the orientation of your roof to the north or in the shade for example. To avoid this phenomenon of greening, it is important to ensure good ventilation of the underside of the tiles in order to accelerate their drying out. The rules of the profession also recommend regular maintenance of the roof in order to slow down this proliferation. It should be noted that greening, if regularly maintained, does not affect the intrinsic quality of TERREAL clay tiles.

Renovating your roof, an investment to preserve the environment. 30% of heat loss occurs through the roof. A regularly maintained and renovated roof therefore represents a considerable saving for the household and helps to protect the planet. Tiles that are well installed and regularly monitored also ensure that the insulation is waterproof and well protected, as it can lose much of its capacity, like some traditional wools, if rainwater infiltrates. Guaranteed for 30 years against frost, with regular tests according to the 5 existing methods in Europe, and against deterioration of appearance, Terreal tiles are designed to withstand all types of weather. Terreal's fixing and accessory systems can withstand the increasingly frequent extreme conditions and withstand winds of over 190 km/h.

To choose the right tile, you have to take into consideration the specificities of the region, the slope of the roof, the style of the house or building, the desired look and finally the budget. Terreal's offer allows you to find the tile format and colour that most closely matches the tile on your roof. Durable, Terreal tiles, with their diversity and richness of colours, allow you to carry out a renovation that is fully integrated into the environment of your house, while respecting your landscape. Don't hesitate to ask a professional to guide you in the choice of the Terreal tile best suited to your project and, above all, to consult him/her on the choice of accessories that will guarantee perfect aesthetics and lasting waterproofing.

Some older product ranges can be replaced by current products. All replacement procedures should be investigated by the façade technical department who will then propose the most suitable solution in terms of product and fixing system.

Preventive anti-graffiti treatment can be a suitable solution for protecting the lower parts of structures in some cases. Some of the products used may change the visual appearance. A preliminary test on the substrate is preferable. A product such as Silreca sacrificial from Reca or Protectosil WS 405 from Evonik Industries can be considered. The duration of protection of the work with this type of product may vary over time depending on the environment and the type of product used. Cleaning solutions exist (high pressure sand/water spraying, cleaning with chemical solvents). The study of these solutions is to be seen with a specialised company.