Amidst all the personal opinions, it should not be overlooked that the chosen plaster must be adapted to the respective DIN standards and the generally accepted rules of technology ([a.a.R.d.T]) for the specific substrate. The plaster substrate and its pretreatment play a crucial role in the selection of the plaster group and are provided with recommendations by the manufacturers of the stone types used, which must be strictly observed. The composition and use of the plaster mortars are further regulated according to DIN V 18550 and DIN EN 13279.
A basic rule, for example, is that the plaster may never be harder than the substrate to compensate for thermal and static stresses. A lime-cement or cement plaster is a relatively dense, capillary-increasing non-absorbent plaster that is not suitable for very soft aerated concrete. Therefore, for interior plaster, either a hydraulic lime plaster (MG P Ic), a gypsum lime plaster (MG P IVc), or a lime gypsum plaster (MG P IVd) is appropriate.
Besides, gypsum must not come into contact with fresh, unset concrete or cement-containing mortar, because the dissolved CaSO4 in the cement can trigger the so-called “sulfate attack” by forming, among other things, the mineral salt ettringite. The salt causes severe plaster damage due to its volume expansion.
Decisions for or against certain building materials or building component structures should therefore not be determined exclusively by personal preferences, the incidental offer at the hardware store, or the profit calculus of the construction company, but rather by the structural and building physics requirements.