The impact of renovation plasters on desalting and drying of damp walls

Abstract

Renovation plasters have been used in the construction industry since the early 1970s. Although the benefits they offer are obvious, there were also critical opinions about the adverse effect of the plasters on the durability of the walls. The complaints mainly concerned the tendency of renovation plasters to accumulate water in the wall, which in the winter time resulted in peeling of the plasters. As a result, more and more often conservators began to refrain from applying renovation plasters in historic buildings in favour of lime plasters without the porosity-increasing additions. The article presents an analysis of the walls which can be encountered in the renovation practice. For selected buildings undergoing renovation, the moisture content of walls, their strength, microstructure and water sorption were determined. Renovation plasters, whose microstructure and properties matched the properties of the walls, were used for their renovation. Plasters with optimal microstructure enabled salt accumulation, crystallized salts did not lower their durability and did not lead to cracking or peeling.