The cellar fungus often grows in areas with moist or wet conditions such as groundwork, rising damp or leaking sewer systems or roofs. The cellar fungus grows rapidly and affects both softwood and hardwood. Wood species of sustainability class I are not affected, class II rarely. Because of the consistently high humidity in crawling spaces, these areas are easily affected, as are roof structures in case of leakage.
The spores of the cellar fungus sprout quickly in favourable conditions, after which the fungal threads, called hyphen, penetrate the wood. These hyphen have a diameter between 0.0005 and 0.005 mm and are not visible to the naked eye. Initially, the hyphen are white. On the wood surface, mycelium, entangled hyphae are rarely formed. In some places, for instance under linoleum and behind plinths, a thin degradation can be visible similar to that of dry rot. If mycelium develops on the surface of wood or stone, this only consists of thin hyphen of 1 to 2 mm that branch out in a fan-shaped manner and that look like roots or vines and have a dark brown to black colour. Fruiting bodies are rarely found in buildings. Initially it consists of an ochre coloured thin plate of about 3 mm, which later turns olive brown, with an irregular shape, covered with small nodules. It may vary in size from several centimetres to over 50 cm in diameter. The edge remains yellowish white. The spores created by the fruiting body, are dark brown, oval and very small, with a length of 0.008 to 0.0013 mm and a diameter of 0.005 to 0.009 mm. They spread through the airflow or insects, which completes the cycle.
The cellar fungus is family of the brown rot inducing fungi. The degradation of cellulose and hermicellulose, destroys the walls of the wood cells. At first, the wood has a dark discolouration that can turn almost black in an advanced stage. Characteristic are the cracks that run in the fibre direction of the wood. This is often visible in smaller wood, such as in windows and frames, whereas in larger wood, such as beams cracks will also be visible, perpendicular to the fibre direction, causing cube-shaped elements similar to the damage caused by dry rot, but less sharply defined.
Another important characteristic of the cellar fungus is the interior deterioration of the wood, in which a thin layer of 3 to 4 mm of healthy wood remains in tact at the surface. Even in an advanced stage, often just a small deviation and discolouration of the surface is the only signal that the wood has been affected by cellar fungus. For non-experts, the cellar fungus is hard to identify.
Not only because of the germination of the spores can wood be affected by cellar fungus, but also by hyphen of previously inflicted damage. Cellar fungus affects wood with a moisture level of 40 to 60% with an optimum of more than 50% In 21 degrees it develops the fastest, and in 35 degrees it still shows minor growth. In 0 degrees the growth stops, but even -30 degrees won’t kill it. For a treatment against cellar fungus or other fungi, please contact the EWS.