Effect of built-in mineral wool insulations durability on its thermal and mechanical performance.

Energy efficient buildings are unimaginable without highly insulating thermal envelopes. Mineral wool among others is a popular material for thermal insulation. Architects and engineers usually use the data given by the manufacturer in the specification of the material for their building physical design. Such data are obtained from laboratory measurements, carried out on non-aged, and dry samples. However, moisture could affect the thermal performance of insulation materials and may affect the durability too. In the research, we examined stone mineral wool hardboard thermal insulations, which were obtained from a flat roof. The samples looked differently: some of them were in good condition and maintained their load bearing capability, but some were spoiled and soft. We measured and compared the used samples' thermal conductivity, sorption isotherm and deformation under compressive force to new etalon samples. We also investigated the reason behind the lack of load bearing durability of the built-in and spoiled mineral wool boards using scanning electron microscopy and derivatography. In our study, we show how built-in conditions changed the thermal and mechanical properties and thermal performance of the mineral wool insulation layer, which could degrade by up to 40% in terms of thermal resistance under built-in conditions due to certain spoiling and production mistakes of mineral wool. [ABSTRACT FROM AUTHOR]