The "Mérule", also called "leprosy of the houses", is a destroying mushroom which rages in the damp zones. It attacks the frameworks and panellings of old, wet and badly ventilated houses, or to second homes unoccupied during several months and where the air is confined.

When the conditions are met, the "mérule" develops in an impressive way since it can reach eight meters, growing in all the directions, by 4 mm per day or 12 cm per week, all the more quicky as the atmosphere is confined.

This mushroom is a true disaster insofar it can totaly destroy a residence. However to prevent the appearance of this mushroom, greedy of "cellulose", it is necessary to prevent from leaving in wet corners : paperboards, woods and books.