Smulski, S.
1996
Building Material and Wood Technology http://www.umass.edu/bmatwt/index.html
| More than 5% of all construction lumber manufactured each year in the United States is used to replace wood that has decayed in service. This need not be the case. Damage to wood-frame buildings by mildew, mold, staining fungi, and decay fungi is entirely preventable. Their presence points to design flaws, poor workmanship, and neglected maintenance.
Microorganisms
The microscopic organisms that discolor and decay wood belong to a huge group of primitive plants known as fungi. Unable to produce their own food, fungi feed instead on natural substances that make up organic materials like leather, cloth, rattan, paper, and wood.
Mushrooms that spring from lawns and tree trunks are fungal "fruits". They release millions of dust-size spores that are scattered helter-skelter by wind. When the conditions of the surface they eventually settle upon are right, spores germinate, sending out thread-like filaments called hyphae. Enzymes secreted by hyphae break down organic matter so fungi can use it for food.
Before fungi can colonize wood, four requirements must be met: an oxygen supply, temperature in the 40 to 100 (F range, a supply of sufficient moisture, and a food source (wood). Infection can be prevented by eliminating any one of the requirements. Obviously, it's hard to limit oxygen. Temperature control is tough too, since most living things thrive in this range. And even at subfreezing temperatures, many fungi don't die, they just go dormant.
The most effective "method" of preventing fungal deterioration of wood is to keep it dry. Most fungi need a wood moisture content of at least 20% to carry on. With the moisture content of wood indoors over most of the United States cycling annually between 6% and 16%, it's too dry for most microorganisms to get started.
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