Damage assessment of early 20th century stone imitating mortars

The present research evaluates damage problems of historic stone imitating renders. Such decorative mortars were applied on façades to create the illusion of a French sandstone or limestone masonry. Visual analysis of three listed case studies from the early 20th century sheds light on the lifespan of these materials by assessing their characteristic damage patterns and helps to understand the causes of their degradation. Soiling, cracks, adhesion problems, biological growth and surface erosion are observed and discussed. Although the renders are in relatively good condition, discolorations disrupt the monumental value and deterioration often increases after improper conservation interventions.