The term of a historic plaster or surface coating, respectively, denotes a layer or a multilayer of materials firmly bonded to the substrate, whose structural and technical condition significantly affects not only the aesthetic effect, but mainly the service life of this surfacing. Due to the permanent exposure of plaster surfaces to the external environment (in the exterior as well as the interior), they belong to the group of the most exposed parts of historic and heritage buildings, often exhibiting a high degree of degradation and disintegration. The consolidation and rehabilitation of plasters with, among other things, a degraded binder component, damaged structure and insufficient adhesion of individual layers to each other and to the masonry substrate is a challenging task in the restoration of historic buildings. The paper presents the alternative of strengthening degraded surface layers by means of nanomaterials based on calcium hydroxide applied by the surface penetration method.