In this study, the behavior of tannin-modified and pre-heat treated wooden beams in different climatic conditions were determined. For purpose; Samples prepared according to TS EN 386 standards from Scots pine (Pinus sylvestris L.), oak (Quercus petraea L.) chestnut (Castanea sativa Mill.) woods impregnated with acorn tannin pre-heated for 2 hours at 150°C 160°C. After samples conditioned 20°C ...