The lumber Holzhof uses, whether square or round, comes mostly from certified forests, the majority of which are situated in the north of Sweden. The wood is processed directly in our plant, using vacuum pressure impregnation techniques in an autoclave, only once all other operations (e.g. the cutting or working of the piece) have been completed. Only in this way, in fact, will the treatment with water-soluble salts be homogenously impregnated throughout the material, thus ensuring (thanks also in part to the high-quality products we use) that it is extremely resistant to aggressive climate and/or parasite effects, while preserving its qualities over long periods. Impregnation is carried out in accordance with the relevant European standard, UNI EN 351-1.