Hydrophobicizing additives are water-redispersible powders or aqueous dispersions containing: a) water-insoluble, film-forming base polymer(s) based on homopolymers or copolymers of one or more vinyl esters of optionally branched C.sub.1-15 alkylcarboxylic, (meth)acrylic esters of C.sub.1-15 alcohols, vinylaromatics, olefins, dienes and vinyl halides, b) one or more hydrophobic organosilicon compounds, fatty acids, or derivatives thereof, or hydrocarbon waxes, and c) one or more protective colloids,wherein the proportion of the component b) based on the total weight of the component a) is more than 30% by weight.