Stone wool or glass mineral wool. Which is the most suitable material for insulating partition walls and attic space?

Which insulation material to choose for attic insulation and partition walls?

For insulating cavities in residential walls and attic spaces, two of the most common insulation solutions are stone wool or glass mineral wool. While both insulations are excellent choices, understanding the advantages of both materials can be helpful in making the right decision.

Stone wool or glass mineral wool – thermal performance

The main reasons people choose to insulate are for thermal and acoustic control. For both of these characteristics, stone wool performs slightly better than glass wool. For example, stone wool offers an R-value of 1.43 at 50mm, while glass wool has an R-value of 1.25 at the same thickness. In terms of price, stone wool is more expensive, so if you are looking for a budget solution, glass wool is the better option.

* You can read what lies behind the term R-value and what its values ​​indicate in the article: Insulation Rating – How to Calculate the Efficiency of Stone Wool!

Weight

It should be noted that while you can get a higher R-value from rock wool, the material also weighs more. There are applications where the insulation will be laid directly on top of the drywall, such as in attics. In these cases, the weight of rock wool may be too much, making glass mineral wool a better choice.

Stone wool or glass mineral wool – durability

Glass mineral wool with a lower density is much more flexible. It is worth noting that despite its flexibility, the interconnectedness of the glass fibers does not allow the wool to sink into the wall cavity and settle. Stone wool is much harder due to its density and has absolutely no chance of sinking or settling into the cavity wall over time. Some installers prefer the rigidity of stone wool to the flexibility of glass mineral wool. Working preferences can vary between installers and the choice is largely based on personal preference.