Hygrothermal Performance of Exterior Insulation Solutions with Thick Plaster Systems (ETICS) Under Accelerated Weathering in Climate Chamber

Abstract

Modern ETICS plasters work well only when the exterior surface is fully watertight; they fail if moisture – whether trapped in-wall or from leaks – is present behind the plaster. Additionally, ETICS is unsuitable for historic buildings because its modern Dinish and visible insulation patterns clash with the building’s character. A potential remedy is to use thicker, vapor-open plasters along with hygroscopic insulation materials. Here, 2 such systems were studied in a climate chamber on 4 different insulation materials to assess hygrothermal performance and gather reference data for modelling. Test samples were subjected to various drying, wetting, heat and frost cycles while temperature, humidity and moisture content were measured. The hygric buffering effects of wood Dibreboard and to some degree of phenolic foam insulation were evident both in wetting and drying episodes. The hydrophobation showed only a brief initial effect under prolonged water exposure, yet it still reduced moisture content in 3 cm natural hydraulic lime plaster by 1.5–2× at the end of the experiment compared to untreated samples; its impact on 1 cm lime-cement plaster was limited. The measurement results will be used for hygrothermal model calibration, which will form the basis for long-term assessment in along with separate measurement of damage criteria.