Abstract: In known methods of preservative or upgrading heat treatment of wood, the starting material (2) is subjected to a selection process in order to select out wood with defects (6) (knots, cracks, resin ducts). A not inconsiderable part of the starting material is hereby not used to obtain thermally preserved wood. According to the invention the defects (6) are sawn out of the starting material, whereafter the remaining defect-free parts (14-1) are once again combined by finger jointing to form larger parts (16). The thus jointed wood structures (16) can be further assembled by lamination into even larger wood structures, the laminated wood structures (18). These can be applied particularly well as exterior cladding or as window or door frame in the building industry.