The black or green spots that sometimes appear on roof tiles are nothing more than fungi and algae – micro-organisms that grow on the porous surface of the tiles.

Fungi appear because of fungal spores already present in the atmosphere and the natural structure of the tiles, which have pores in which the fungus can grow.

The pores, however, are necessary and a mark of quality that makes clay roof tiles stand out from all other roofing materials. Thanks to their porous structure, tiles breathe, naturally expelling water vapour, balancing the humidity of the home and helping to create a pleasant microclimate under the roof. In addition, by absorbing moisture at night and releasing it through evaporation during the day in the summer months, they provide natural cooling of the roof.

The pores of roof tiles are therefore something we need, and it is a mistake to prefer tiles and materials that do not breathe.

Thanks to the careful selection of their raw materials and high firing temperatures, Panagiotopoulos roof tiles have an ideal porosity which, while providing all the benefits of breathability and moisture release, makes them particularly resistant to the growth of fungi.

Nevertheless, because of their natural structure and under the influence of aggravating external factors such as:

constant shading of the roof,
surroundings with dense vegetation,
high humidity in the area, etc.,

fungi may occasionally appear on the roof.

This should not worry the owner in the first place: apart from appearance, it does not affect the quality of the tiles in any way (in fact, many owners and architects look for tiles with fungal spots on their surface to achieve an aged look), and it is something that can be dealt with very easily.

As these spots are fungi, a special anti-fungal / anti-mould product can be applied to the tiles with a sprayer; such products are available from building-materials and paint shops (many companies offer them).

Depending on how each product works, the fungus is killed within 1–2 days and is then washed away even by rain, or with a light rinse that cleans the tile thoroughly. If a pressure washer is used, care is needed so that excessive water pressure does not shift or break the tiles.

The high strength (the highest on the Greek market) and excellent fit of Panagiotopoulos roof tiles allow this work to be done on the roof even by a non-specialist, without fear of damaging the roof, provided due care is taken.

There are also products on the market with a protective action: after eliminating the fungus, they keep their anti-fungal properties, protecting the tiles for several more years.

In any case, we recommend not using or preferring materials that, although advertised as protecting against mould and fungi, actually contain sealants that block the pores and stop the tile from breathing, and may even cause damage in the long term (sealing the pores of roof tiles in any way, e.g. painting or varnishing, must be avoided and constitutes a breach of the terms of the guarantee provided).