What does the R-value measure in building materials?

The R-value is a crucial metric in building materials, specifically related to thermal resistance. It quantifies the material's ability to resist heat transmission. Higher R-values indicate better insulating properties, meaning that the material can more effectively slow down heat transfer, keeping buildings warmer in the winter and cooler in the summer. This measurement is essential for energy efficiency in construction.

In contrast, other options such as weight, durability against wear, or resistance to moisture do not reflect the thermal performance of a material. Weight pertains to how heavy the material is, which does not influence its insulating qualities. Durability against wear generally refers to how well a material can withstand physical wear and tear over time, unrelated to its ability to provide thermal insulation. Resistance to moisture relates to how a material performs in wet conditions but does not correlate with its thermal resistance characteristics.

Thus, R-value is specifically focused on heat transmission resistance, making it the pivotal factor in evaluating a material's insulation efficacy.