Density has an effect mainly on mechanical properties of an insulation material.

The effect of density on product properties varies from one insulation material to another and this is as well valid even within the group of different mineral wool insulation materials (glass wool, stone wool, ULTIMATE). Therefore it is not useful to compare different materials just by their density.

The thermal conductivity is the measure to look at when speaking about heat transfer. In the case of mineral wool, the thermal insulation quality of the materials depends mainly on the respective fiberisation process and the mats structure. During the production of Glasswool and ULTIMATE the raw material is fiberized 100% into wool. The stone wool process is creates a significant share of shot content (unfiberised pieces) that adds weight but does not contribute positively to the thermal nor to the acoustic properties of the final product.
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