In this study, heartwood, sapwood and copper-chromium-boron (CCB) impregnated sapwood samples of various tree species, including Scotch pine (Pinus sylvestris L), Caucasian spruce (Picea orientalis (L.) Peterm), European beech (Fagus orientalis L.) and common alder (Alnus glutinosa subsp. barbata), with dimensions of 20x20x300 mm, were investigated. These samples were subjected to soil contact, specifically under conditions of hazard class 4 according to EN 252, for a period of 3 years. The study was conducted in four different provinces of Turkey, namely Trabzon, Muğla, Çanakkale and Elazığ, each of which is characterized by different climatic conditions. The climatic index and soil structures of the sites were studied. The visual decay, weight loss and density values of the samples collected from the test sites were evaluated. Elazığ had the lowest visual decay rate, the lowest weight loss and the highest density. More negative values were observed in Çanakkale, Muğla and Trabzon. In terms of climate type, it can be said that the Scotch pine and Caucasian spruce wood samples have higher resistance than the European beech and common alder samples. In particular, the heartwood of conifers was found to be more durable than the sapwood. In addition, no deformation was observed in any of the impregnated wood samples. All impregnated wood samples showed very good durability.