Abstract: A granular expanded mineral material, e.g. vermiculite, is caused to move in the form of a free flow (28) through a mist (46) produced by an atomizer (29). A waterglass solution and a hardener therefor are supplied through conduits (32,43) and (33,42) respectively, to the intrior of the atomizer (29) for co-atomization to produce said mist (46). A small amount of hydrophobizing agent non-emulsifiable in the waterglass solution is introduced into the stream of waterglass solution in the conduit (32,43). An in-line mixer (53) is built into that conduit immediately ahead of its exit (45) to the atomizer. By passing through the atomized mist (46) the grains of the expanded mineral material are individually coated with a film of waterglass solution and hardener with hydrophobizing agent finely distributed therein. The film-coated granular material is immediately thereafter pneumatically conveyed to a place of deposition on a surface, e.g.

Abstract: To build up a screed coat on a roof surface, a granular expanded inorganic material is subjected to an atomized spray of an adhesive consisting of a solution of waterglass and a hardener therefor so as to form a thin film of adhesive on each grain of the material, and the spray coated granular material thus obtained is immediately conveyed to and poured out on the roof surface. It is then spread over the roof surface and compressed to form a coherent layer constituting the screed coat. This may form a base for the superposition of insulating boards and a waterproof roof covering. The method is particulary useful in the renovation of deficient roofs originally built without a gradient towards outlets or gutters.