Water absorption characterisation of historic plasters. Comparison of different methodologies in a case study in Tyrol, Austria.

Abstract

Balancing conservation of historic buildings and improvement of their energy performance is a challenging task that involves multiple factors. Prescriptive standards for interventions of internal insulation in modern materials are not compatible with conservation of historic plasters and thus a more detailed and sympathetic approach must be used. Knowing the hygric behaviour of historic plasters is a prerequisite in the assessment of any intervention of internal insulation. In this paper, four different methods for the quantification of the water absorption coefficient, laboratory and onsite based, are presented and applied to an outstanding case study in Tyrol (AT). The variability observed, between methods but also between the different layers of plasters found onsite and even between measurements, highlighted the need for robust guidelines for the application and interpretation of the results. This study summarises the numerous factors influencing the result of the water absorption measurement and shows a first investigation into one of these aspects (heterogeneity of the wall). Numerical simulation has proven to be an effective tool to use in combination with experimental results in testing the effect of the different parameters affecting the water absorption characterisation of historic plasters.