A non-structural work method wherein prefabricated flat elements, particularly plates, are provided which comprise a plaster body and at least one paper facing sheet with at least one outer layer having an exposed outer surface ready for decoration, as well as at least one complementary jointing plaster particularly suitable for finishing a joint; and said flat elements are assembled, particularly by means of a plaster, whereafter the joints are finished using said complementary plaster to form an exposed outer surface that is relatively uniform even at the joints. The structure and/or composition of the paper facing sheet and the composition of the complementary plaster are adjusted in relation to one another so that when the complementary plaster has dried, a surface having one or more substantially uniform physical properties, including colour or shade, is achieved over the whole of said surface, and particularly on the exposed outer surface of the joints.