Bio-based materials are gaining importance in the building industry, as the focus on sustainability and life-cycle-assessment has increased dramatically over the last decade. Wood and wood-engineered products as well as insulation materials made from flax, hemp, etc. are hence increasingly used. These materials originate from renewable resources and are often biodegradable, which can cause problems when bio-based materials are exposed to moisture and temperature conditions that are favourable for fungi. Fungal damage is not only an aesthetical issue, but can also severely compromise the structural integrity of a building component. Several standards exists for assessing the inherent resistance of wood species and the efficacy of wood preservatives, and are generally regarded to be sufficient and adequate. However, the existing standards are typically inadequate for the correct qualification of new wood products, whose durability is not enhanced with biocides but by new technologies, such as chemically modified wood (acetylation, furfurylation, etc.), thermally treated wood and also engineered wood products, such as glue-laminated wood, wood-based panels and wood treated with water repellents. In order to know whether the existing standard tests can be applied for bio-based materials other than (impregnated) wood species, certain material characteristics and their influence on fungal resistance as well as the standards’ test methodologies will need to be well understood. Therefore, it is key to unravel the influence of different material characteristics, like the material’s chemical components, its spatial structure and its moisture dynamics, all contributing to the material’s durability or resistance. In this paper, an experimental method is described in which the structure of a material is eliminated, so the chemical component of the material’s resistance can be separated from the other material characteristics. In se, the nutrient value of a material is tested for decay fungi, without the material’s structure and moisture dynamics playing a role.

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