Dry Rot

Dry Rot

Dry rot refers to the decay of timber in buildings and other wooden structures caused by certain fungi. It would appear to be a paradoxical term seemingly indicating decay of a substance without the presence of water. The term is most commonly used in reference to the decay of building timbers. It refers to damage inflicted by either: Serpula lacrymans (formerly Merulius lacrymans) predominantly in the United Kingdom and northern Europe; and/or Meruliporia incrassata (which has a number of synonyms, including Poria incrassata and Serpula incrassata) in North America. Both species of fungus cause brown rot decay, preferentially removing cellulose and hemicellulose from the timber leaving a brittle matrix of modified lignin. Eventually the decay can cause instability and collapse in houses, wooden ships' hulls, and other wooden structures.

When applied to these fungi, the term is a somewhat misleading misnomer as both species require an elevated moisture content to initiate an attack on timber (28–30%). Once established, the fungi can remain active in timber with a moisture content of more than 20%. For example, at relative humidities of the surrounding air below 86 percent, growth of serpula lacrymans is inhibited, but it can stay dormant at relative humidities down to 76 percent These relative humidities correspond to equilibrium moisture contents of wood of 19 and 15 percent, respectively.

The perpetual saturation of wood with water inhibits dry rot, as does perpetual dryness.

References

1. ^ Ramsbottom J (1923). A Handbook of the larger British Fungi. British Museum. London. 
2. ^ J.W. Palfreyman, The Domestic Dry Rot Fungus, Serpula lacrymans, its natural origins and biological control. Ariadne workshop 2001.
3. ^ The Times (London), Tuesday, 12 March 1793
4. ^ A treatise on the dry rot in timber. http://books.google.com/books?id=uEkVAAAAQAAJ&printsec=frontcover&dq=A+Treatise+on+the+Dry-Rot#v=onepage&q=&f=false. Retrieved 2009-09-12. 
5. ^ "Wooden Ships and Fungi". http://www.uoguelph.ca/~gbarron/MISC2007/jun2007.htm. Retrieved 2009-09-12. 
6. ^ Schilling, J.S and Jellison, J. (2007). International Biodeterioration & Biodegradation. Elsevier. 
7. ^ Schilling, J. (2009). Holzforschung. Elsevier. 
8. ^ Coggins, C.R. (1977). Aspects of the growth of Serpula lacrymans the dry rot fungus. PhD.Thesis. University of Liverpool.