The present invention provides a construction assembly for interior works, comprising: prefabricated elements, preferably flat prefabricated elements e.g. gypsum fiberboards, cement fiberboards, gypsum wall boards or plaster boards, wherein said prefabricated elements comprise a coating layer formed of at least one skim coat deposited on said prefabricated elements by a coating device; and at least one jointing material, e.g. a sealing coat, joint coat and/or joint pointing coat, which joints adjacent said prefabricated elements to form a substantially plane outer surface comprising the visible surface of said at least one jointing material and the visible surface of the skim coated prefabricated elements, wherein said at least one jointing material and said at least one skim coat comprise a mineral filler, a binder and water; and wherein the composition of said at least one jointing material and said at least one skim coat are adapted to each other, whereby said at least one jointing material and said skim coat form, both in a dry state, a substantially homogeneous outer surface having over substantially all its surface at least one of the parameters comprised in the group consisting of coloration, reflectance factor and surface water absorbability which is substantially homogeneous over said surface; and whereby said outer surface is ready to be decorated. For instance, said at least one of the parameters differs by no more than 10%, preferably no more than 5%, at different parts of the overall surface, so that at least 90%, preferably at least 95%, homogeneity is achieved.