What factor, along with material and thickness, determines the R-value of insulation?

The R-value of insulation is primarily determined by its ability to resist heat flow, and one of the key factors that contributes to this characteristic is density. Density refers to how much material is contained within a given volume of insulation. Higher density materials generally trap more air, which improves their insulating properties and increases the R-value. This means that as insulation density increases, its capacity to resist conductive heat flow also increases, leading to better thermal performance of the insulation in an attic or any other insulated space.

While material and thickness are critical factors, density plays an equally important role in enhancing the effectiveness of insulation, ensuring that the space remains energy-efficient and comfortable.