It is the first application in the transition to finishing works after the completion of the rough state of the constructions. It is a mixture prepared with water, cement and sand, it is applied to the walls and the entire surface before painting. The mixture, which is prepared with lime instead of cement, is generally soft in consistency and is easy to apply.

The humidity of the outer wall primarily depends on the water absorption feature of the outer plaster or outer coating. Likewise, the drying process depends on the capillary water absorption and vapor permeability properties of the wall and coating. In this respect, the type of surface coating to be chosen and the type of wall material determine the equilibrium humidity that may occur in the wall over time. The capillary water absorption of Ytong material is low. For this reason, the moisture that will leak from the outer coating in any way can be thrown out again by evaporation before it has the opportunity to progress within the wall. This is why it reaches the fastest and lowest equilibrium humidity in the creaky, completely unprotected Ytong walls. Ytong material has high thermal insulation properties thanks to its porous structure.

As soon as the thermal insulation properties of the outer wall materials increase, the mineral plaster or coatings on them heat up more in summer. As a result, the plaster or coating must be as elastic as possible in order to safely meet the thermal expansion of the plaster or coating.