The invention relates to a surface covering system intended for a surface in the form of a wet room floor, a roof or another substantially flat, delimited surface which is exposed to water and needs drainage, and to methods for preparing such a system. The surface covering system comprises at least one plate with a mark showing a drainage point and a substantially flat lower surface and an upper surface with a first decline towards the mark. The invention is characterized by that the first decline is circular and has a radial slope (α) directed towards the mark from every point on the at least one plate. The decline creates a cavity in the plate in the shape of at least a part of a blunt virtual cone with the apex of the cone directed towards the mark, achieving a modular surface covering system with an even circular decline.