The invention relates to improved non-efflorescing cement-free and water-dispersible powder building material compositions comprising a homopolymer or copolymer as binder, useful for the preparation of wet formulations of plasters grouts, waterproofing coatings or mortars for the construction and the civil engineering industry. The binder is obtained by spray-drying or lyophilization of a dispersion containing a polymer and a protective colloid. These compositions also comprise a deprotection agent and a specific adsorbent filler. The invention also refers to the methods of preparation of these dry compositions and wet formulations, the application of these latter onto the surface of buildings or civil engineering works, the so obtained coatings as well as the so coated elements. The hardened products obtained therefrom are remarkably water-resistant, non efflorescent and easy to obtain.