The fungi strains Alternaria tenuis C.G. Ness and Ulocladium alternariae (Cke.) Simmons could be isolated from black coloured glass fibre wallpaper. It was investigated that glass fibre wallpaper and covering pastes were not substrate medium but were settled by fungi when there were nutrition substances under or in the air volume of the wallpaper. Both isolated fungi strains converted carboxymethyl-cellulose as alone C- and energy source. The fungicide Smotilon AM limited the spore germination growth of both strains with 0.5% solution. The formation of the biotop glass fibre wallpaper for fungi was discussed.