Durability of timber products –Part 1: Inventory and evaluation of above ground data

IRG/WP12-20498

C Brischke, L Meyer, G Alfredsen, M Humar, L Francis, P O Flæte, P Larsson Brelid

The material-inherent resistance of wood is one of the most important qualities influencing the durability of timber. Hence, it has also a major effect on the service life to be expected from a timber construction. In addition, design details and the respective climatic conditions determine durability and make it impossible to treat wood durability as an absolute value. Moreover, the reference magnitude varies between locations because of climatic differences. Durability classification is therefore based on comparing a certain performance indicator between the timber in question and a reference timber. Finally, the relative values (= resistance factors) are grouped and related to durability classes, which can refer to a high range of service lives for a certain location. The insufficient comparability of such durability records turned out to be a key problem for the service life prediction of timber structures, even when the climatic conditions are clearly defined. This study aimed therefore on an inventory of literature data, directly based on service life measures, not masked by a durability classification schedule. It focused on natural durability of timber tested in the field under above-ground conditions. In total 395 durability recordings from 31 different test sites worldwide and based on ten different test methods have been considered for the calculation of resistance factors: 190 for hardwoods and 205 for softwoods. Nevertheless, the considered datasets were heterogeneous in quality and quantity; the resulting resistance factors suffered from high variation. In many cases information was presented too condensed and incompletely, which is inescapable for instance in journal articles. To increase the amount of available, comparable, and directly service-life related data a reliable platform is needed. A proposal for a corresponding data base is provided in part 2 of this paper.


Keywords: field tests, durability classes, resistance factor, service life prediction, test methodology

Conference: 12-05-06/10 Kuala Lumpur, Malaysia


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