Is Dry Rot Fungus Dangerous?

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Dry rot fungus

Dry rot fungus- see the arrow

The dry rot fungus, Serpula lacrymans, is one of the most destructive wood decay fungi in buildings in many countries around the world. Due to its destructive nature, Serpula lacrymans is often referred to as a “building cancer”. 

It can also cause structural damage to masonry.  The fungus thrives in poorly ventilated, dark places with elevated moisture levels. As such, it is frequently able to spread extensively before the damage is noticed. Dry rot fungus is almost completely restricted to the built environment.

It is a good coloniser of wood within the built environment because it has a highly efficient transport system which allows movement of water, nitrogen, iron, etc via specialised root-like structures (rhizomorphs) and effective solubilisation system which allows extraction of metal ions from stone and plaster work.

The dry rot fungus uses non-enzymatic mechanisms to modify lignin and initiate the breakdown of cellulose. Hydrolytic cellulases and oxidative enzymes are then used to fully degrade and metabolise the cellulose. Various myths associated with the destructive nature of the dry rot fungus often lead to use of harsh and destructive treatment that cause more damage to the building than the fungus itself.

For example, it is erroneously believed that the fungus is indestructible and that the whole building would have to be pulled down once infested. The dry rot fungus, however, is vulnerable to dry conditions and hence would not survive for long in absence of moisture.

Is dry rot fungus dangerous to your health

There are no known toxic chemical compounds produced by the dry rot fungus. However, existence of asthma associated with this fungus has been documented. The sensitizing role of this fungus was confirmed in atopic and asthmatic individuals by both skin tests and by bronchial provocation tests. A small number of confirmed cases of hypersensitivity pneumonitis (allergic alveolitis) caused by the dry rot fungus have been reported.

How to detect dry rot fungus

Dry rot fungus is likely to be found in buildings where bad maintenance, particularly of old properties, and inappropriate design or alteration may result in water intrusion. In the early stages of infestation, the dry rot fungus is difficult to visually distinguish from other wood rotting fungi without proper laboratory testing.

However, at advanced stage of infestation when the fruiting bodies have developed brown spore dust, the fungus is relatively easy to distinguish from other wood rot fungi. Unlike other wood rot fungi, the dry rot fungus is able to spread to other wood, even through masonry materials. This ability to spread is one of the distinguishing and threatening characteristic of the dry rot fungus.

How to control dry rot fungus

The dry rot fungus can be readily controlled with the proper combination of environmental manipulations and building considerations coupled with the proper use of wood and masonry preservatives.

Other wood rotting fungi in houses

Another type of rot caused by fungi on wood in houses is the wet rot. Unlike the dry rot fungus, wet rot fungi destroy both cellulose and lignin, leaving the colour of the wood largely unaltered but producing a soft felty or spongy texture without cross cracks. Wet rot could either be brown or white rot. 

Common white rots are caused by fungi Donkiporia expansa, Asterostroma spp, Pleurotus ostreatus and Phellinus contiguus. Brown rots cause the wood to become darker in colour and to crack along and across the grain; when dry, very decayed wood will crumble to dust. Many common wet rots are brown rots caused by fungi such as Coniophora puteana, C. marmorata, Paxillus panuoides and Dacrymyces stillatus.


  1. Watkinson, S. C. and D. C. Eastwood (2012).  Serpula lacrymans, Wood and Buildings. In Allen I. Laskin, Sima Sariaslani and Geoffrey M. Gadd, editors: Advances in Applied Microbiology, Vol. 78, Burlington: Academic Press, 2012, pp. 121-149. ISBN: 978-0-12-394805-2 © Copyright 2012 Elsevier Inc. Academic Press
  2. Palfreyman, J. W. (2001). The domestic dry rot fungus, Serpula lacrymans, its natural origins and biological control. In Ariadne workshop.

You can directly contact Mold & Bacteria Consulting Labs with any questions you have about this article.

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Dr Jackson Kung'u
Dr. Jackson Kung’u is a Microbiologist who has specialized in the field of mycology (the study of moulds and yeasts). He is a member of the Mycological Society of America. He graduated from the University of Kent at Canterbury, UK, with a Masters degree in Fungal Technology and a PhD in Microbiology. He has published several research papers in international scientific journals. Jackson has analyzed thousands of mould samples from across Canada. He also regularly teaches a course on how to recognize mould, perform effective sampling and interpret laboratory results. Jackson provides how-to advice on mould and bacteria issues. Get more information about indoor mould and bacteria at

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