(EN) The invention relates to a method for waterproofing lignocellulosic materials by impregnating the lignocellulosic material with a waterproofing agent, whereby the lignocellulosic material is impregnated with a hardenable aqueous composition before or during waterproofing, said composition containing at least one cross-linkable compound, selected from a) low-molecular weight compounds V, having at least two N-bonded groups of formula CH2OH, wherein R=hydrogen or C1-C4 alkyl, and/or one 1,2-bis-hydroxyethan-1,2-diyl group, bridging two nitrogen atoms, β) precondensates of the compound V and & gammad;) reaction products or mixtures of the compound V with at least one alcohol, selected from C1-C6 alkanols, C2-C6 polyols and oligo-C2-C4-alkylene glycols.