Biodegradation of untreated wood foundation piles in existing buildings: part 2 - deterioration mechanisms

September 29, 2007
Publication: Structure Magazine p 53-56

Abstract: Wood-destroying fungi are the predominant damaging biodeterioration agents affecting the performance of untreated wood piles supporting historic buildings today. At the end of the 19th and beginning of the 20th centuries, when this type of building construction was common in urban-fill areas in the northeastern U.S., biodeterioration was not anticipated. Piles were generally cut off below the lowest expected elevation of the groundwater table, and the protection strategy was based on the common assumption that no significant fungal deterioration can occur due to lack of oxygen in a submerged condition. Unfortunately, groundwater levels in many cities receded over the years, resulting in exposure of pile tops to oxygen, subsequent accelerated biological deterioration, and ultimately, the significant settlement of structures.|Part 1 (STRUCTURE® magazine, June 2007) of this three-part series described common investigation procedures and methodologies for assessing the type and extent of deterioration, as well as risk for future settlement damage. This second installment discusses wood destroying fungi and other biological deterioration agents and the associated main deterioration types, as well as how they relate to predominant conditions found in soil environments.