Ali imamo v Sloveniji na voljo naravno odporen les?

V zadnjem obdobju se raba lesa veča, še posebno za gradbene namene. Na prostem je les izpostavljen delovanju biotskih in abiotskih dejavnikov razkroja. Teh procesov ne moremo preprečiti, s pravilnim načrtovanjem konstrukcij, izbiro ustreznih lesnih vrst ali biocidno zaščito pa jih lahko zelo omejimo. Pri izbiri lesa je eden od najpomembnejših podatkov njegova naravna odpornost. Letos je bil objavljen nov standard, ki na tem področju prinaša številne novosti. Najbolj izrazito je zmanjšanje odpornosti macesnovine in hrastovine, predvsem zaradi variabilnosti lesa, ki je v celoti ne znamo pojasniti. V tem prispevku so navedena najnovejša spoznanja in nekateri rezultati, ki se nanašajo na naravno odpornost in življenjsko dobo lesa. The use of wood is increasing in the recent years, predominately in the building sector. Wood in outdoor applications is exposed to a variety of biotic and abiotic degradation factors. These processes cannot be completely prevented, but can be slowed down with proper construction, selection of wood species and/or application of biocides. One of the most important criteria that influences the selection of wood species is natural durability. There has been new EN standard published recently that brings new classification of wood species to durability classes. The most important decrease of durability has been assigned to larch and oak wood, predominately due to the huge variability that cannot be fully controlled. In the respective contribution, new aspects and data that are related to durability and service life of wood are presented.