Decomposition of Wooden Structures by Fungi

Wood has been extensively used as a building material for millennia. Strength-to-weight ratio, workability, relatively low cost, renewability, and biodegradability are among the most desirable characteristics that make it useful for structural purposes. Wood used in the built environment has increased over time and is still the number one material for use in structures today. Despite all the benefits as a building material, it also comes with some problems. Loss of wood products from fungal degradation has been estimated to be 10% of annual harvests (Zabel and Morrell 1992) and is a recognized problem worldwide. Fungi are well adapted to degrade wood and are, in the natural setting, crucial to a healthy ecosystem, functioning by degrading and recycling dead organic matter. Built correctly, wood structures can last for centuries, such as the Hōryū-ji in Japan built in 607 AD, the stave churches in Norway (1150 AD), and, one of the oldest wooden structures in the world, the Midas Tomb in Turkey (700 BC). However, given exposure to the environment and sufficient moisture and suitable growth conditions, a wide array of fungal species threatens wood in service. When left unchecked, wood-decay fungi can quickly destroy affected areas. Most decay fungi that affect structures belong to the phylum Basidiomycota and, to a lesser degree, Ascomycota. This chapter will discuss some of the major fungal species that affect wood structures, growth requirements needed for degradation, and methods used for control.