Experimental set up

Six timber species with different levels of natural durability which are of economic importance for the construction industry in France were chosen for the study. Only the heartwood (or at least the most inner parts of the sawn logs when heartwood was not possible to distinguish from sapwood) was used.

Climatic parameters such as heat, rain, wind and UV radiation strongly affect the esthetic durability and susceptibility to fungal decay of wood used for outdoor purposes. In order to compare the lifespan of wooden commodities under different climatic conditions, four experimental sites were selected in France as follows: Montpellier - mediterranean, Charrey sur Sa˘ne - continental, Bordeaux - oceanic, and Kourou (French Guyana) - tropical. Prior to initiating this experiment, climatic data were collected over the previous ten years at the selected sites and then analyzed.

To estimate the decay potential of different wood species under various exposure situations, various wooden commodities typically meant for outdoor use were manufactured. Identical sets of commodities were made with spruce and poplar (the less durable species) on one side (set of commodities No. 1) and with oak, larch, Douglas fir and maritime pine (the more durable species) on the other side (set of commodities No. 2)