The wood moisture factor on the biological deterioration of wooden structures

Abstract

With sustainability as a growing concern, the rehabilitation of buildings arises as one of the main forms of support for the construction sector. Rehabilitation, in comparison with new construction, is seen as a path to minimize the negative impacts of this activity by reducing, for example, the energy consumption of buildings and its consequent impact on energy production (still meeting the current needs for comfort) and the extraction of raw materials. Wood has a high potential for numerous purposes, also, it is a natural, renewable, and sustainable resource, presenting itself as a promising construction material with enormous importance for the bio-based economy. However, despite being a traditional material, reliable service life prediction of wooden structures continues to be a challenge. Like other biobased materials, wood can be subject to biological deterioration by fungi and insects. The biological agents, when combined with favourable conditions (e.g., temperature, air relative humidity, wood moisture content, etc.), can lead to simply aesthetic damage, reduction in indoor air quality, or compromising its resistant load capacity, creating a risk to human health and safety, in addition to an increase of repair and maintenance costs. Many approaches consider wood moisture content as the key factor to control the activation of the decay process, since fungal colonization of wood requires a minimum moisture content of around 20%. Moreover, though subterranean termites (one of the most damaging wood insects) are able to infest dry wood, contact to moisture is fundamental for effective installation of the colonies. This paper addresses moisture as a conditioning factor in the degradation of wood in construction. The role of water on the development of the biodeterioration processes, the transport of water within wooden elements, as well as how the current normative references address the issue are discussed. Finally, this work presents some of the exiting methods for continuous moisture content monitoring systems that, associated with regular maintenance, can be an alternative to chemical treatments, increasingly limited due to current environmental legislation