STYK, Adam: Cork as a Material Used in Timber Construction (Bachelor thesis) – Technical University in Zvolen. Faculty of Wood Sciences and Technology. Department of Wood Science. Thesis supervisor: doc. Ing. Miroslava Mamoňová, PhD Key words: Cork oak, Quercus suber L., cork, insulation material, granulated cork, scanning electron microscopy, sclereids, suberin, hyphae ABSTRACT The samples of native cork of cork oak (Quercus suber L.) originally from Portugal, the company Amorim SGPS, S.A. and cork thermally treated, taken in situ in the company Drevodom Orava, s.r.o., used as an insulation wall material in timber structures were investigated in the bachelor thesis using the SEM microscope Tescan Vega. The results of the microscopic analysis show that the cork cells on the cross section of suberoderm are thin-walled with penta- up to hexagonal shape without thinning on the radial cut in the shape of radially expanded rectangles embedded one above the other one. The results of the microscopic analysis on the tangential cut were the cavities of circular or lenticular shape typical for the mentioned cut. Mycelium was detected there as well. Layers of pressed cork cells cyclically repeated are typical for the cut. Hyphae were observed close to phelogen as well as close to outer cork layers in the cases of all microscopic cuts. In the surface cork layer, the cells of phloem in clusters containing sclereid supporting the hardness of the cork layer were determined. Crystals of calcium oxalate in lumens were found in some of them. The conclusion that native cork has the properties of biomaterial liable to the action of biotic agents (e.g. moulds) can be drawn. In the case of granulated cork, it was found out that the shape and the structure of cork cells were not changed as a result of thermal treatment. The presence of hyphae was determined in the cork cells.