What does R-Value mean?
The thermal resistance rating or R-Value is the measure used most commonly in the building and construction industry to determine a material’s ability to resist the transfer of heat. The higher the R-Value the better thermal resistance the product will provide.
Glasswool insulation can increase it’s R-Value by either increasing it’s loft (thickness), density (more fibres trapping more air pockets), or a combination of both. Ceiling products tend to get thicker to increase R values, however in walls where space is constrained by the thickness of the timber, higher R-Value products are denser.