December 11, 2016

Dry Rot Fungus: the nightmare

Serpula lacrymans

Some mushrooms do not only bring benefits. In our area of northeastern North America, the dry rot fungus (Serpula lacrymans) has been spreading. In some houses, the contamination may become so irreversible that the whole building must be destroyed.

The fungus attacks lumber in low-ventilated spaces where the temperature is less than 25oC. The wood itself may be relatively dry (up to 20% moisture), but local relative humidity must exceed 76%.

The fungus regulates its moisture by dripping, hence the term lacrymans. The hyphal filaments which constitute the fungus transport water to the substrate (wood), allowing its absorption. These same filaments can penetrate brick or gypsum, which extends the contamination zone and complicates eradication.

It is therefore necessary to circumscribe this zone, to dry it, to remove the affected materials and replace them with healthy materials or even with cement. Sustained ventilation (2.5 l / min) is a valuable help: prevention is possible and always advisable. 

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