InsulCalc

Mineral wool (rock wool) batt: R-value per inch

Short answer

Mineral wool (rock wool) batt adds about R-3.3 per inch, so you need roughly 9.1" for R-30 and 14.8" for R-49.

R-value per inch

R-3.3

Best for

Walls needing fire and sound resistance

Mineral wool (rock wool) batt thickness chart

Target R-valueThickness needed
R-133.9"
R-195.8"
R-309.1"
R-3811.5"
R-4914.8"
R-6018.2"

How much for your home?

Calculate mineral wool (rock wool) batt

Other materials

Blown-in fiberglassBlown-in celluloseFiberglass battOpen-cell spray foamClosed-cell spray foamEPS rigid foam boardXPS rigid foam boardPolyiso rigid foam board

Frequently asked questions

How many inches of mineral wool (rock wool) batt do I need for R-49?

About 14.8" of mineral wool (rock wool) batt, since it adds roughly R-3.3 per inch (R-49 ÷ 3.3).

What is the R-value of mineral wool (rock wool) batt per inch?

Mineral wool (rock wool) batt provides about R-3.3 per inch (a typical value — density and brand vary). So 9.1" gives roughly R-30.

What is mineral wool (rock wool) batt best used for?

Walls needing fire and sound resistance. Compare it against other materials for your target R-value in the calculator.