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. Redispersible dry composition of polymer finish comprising: a powdery organic binder included a polymer obtained by spray-drying or lyophilisation of a dispersion containing said polymer and a protective colloid; a deprotection agent; a specific adsorbent filler; and/or a load; and/or a water retentive agent; and/or a mineral rheological agent; and/or a defoamer; and/or a biocide; and/or a pigment. 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 applications of these wet formulations can be also hardened joints or other hardened products for the construction as well as hardened mass objects. All these hardened products are remarkably water-resistant, non efflorescent and easy to obtain.