Enhancing Performance of Internally Insulated Solid Masonry Wall: Use of Moisture Adaptive Membranes

Moisture-safe retrofitting and energy optimization of facades in existing buildings may be challenging, especially for buildings with preservation-worthy or histori-cal facades. Internal insulation changes the hygrothermal conditions of the origi-nal wall and may cause several problems, like biological growth and masonry de-terioration. This paper explores the use of moisture-adaptive membranes as an additional moisture control measure for safe retrofitting with internal insulation. The results are based on WUFI® Pro simulations. Parameters like minimal and maximal vapour diffusion resistance, relative humidity (RH) range at which the membrane is most diffusion-open and -tight, indoor humidity class, orientation, and insulation type are varied and evaluated with a theoretical mould growth model. Results indicate that the adaptive membrane should already be highly dif-fusion-open at around 75% RH and highly diffusion-tight in periods with low RH (up to around 40%). Results indicate that this would ensure a moisture-safe construction in humidity classes 2-4 using mineral wool. When using organic in-sulation materials, there might be a risk in humidity class 4.