What is the R-Value of Rockwool Insulation? [With Chart]

Lately, homeowners, architects, and builders are finding Rockwool insulation to be more beneficial than other insulations. It has a 3 to 3.3 R value per inch of thickness.

The Rockwool insulation is sustainable, recyclable, fire-resistant, moisture-resistant, easy-to-install, soundproof, highly durable, and has high thermal efficiency. All these key benefits make Rockwool insulation undeniably the best insulation choice for construction.

Also, it is non-organic, meaning no growth of mould, mildew, allergens, or risk of discoloration & rotting etc.

In this short post, you will figure out the R value of Rockwool insulation in comparison to other insulations like fiberglass, cellulose, foam board, etc. Learning which you can decide whether to go for Rockwool insulation or not!

Keep reading to discover more!

What is the R-Value of Rockwool Insulation

What is the R-Value of Rockwool Insulation?

The R value of Rockwool or mineral wool insulation lies between 3.0-3.3 per inch of thickness. It looks like fine thin and intertwined long fiber strands having diameters of 3-4 micrometers. The long fiber strings are pressed together tightly to create a dense mat. So, you can cut them off into larger or smaller batts later on!

The rockwool brings higher thermal capacities and greater heat retention. In other words, it retains the heat inside it for longer time spans! So, you get comfort in the interior living spaces of your homes. Also, you yield lower energy bills! You do not need to adjust the thermostat more often. That’s the benefit!

As it is processed and melted into lava-like substances at 2,900°F, it completely becomes non-organic. You won’t find an element of natural basalt rock once it’s melted at hotter temperatures. Also, it confines the air well inside its rigid strands.

Nevertheless, because of its non-organic nature, it prevents growth of algae, fungus, mould, etc. It includes as much as 75 percent post-industrial recycled material. Also, it prevents discoloration, moisture-trapping, and rotting risks. It repels water and is vapor-permeable so ideal for kitchens and bathrooms where most-heat is generated almost daily. These fiber strands are coated with binders and oiling that curtails dusting pollution.

It is also non-combustible i.e. doesn’t easily ignite. In other words, it is fire-resistant. The mineral wool cannot catch fire up to 1,400°F. Because of which, it is generally installed in building floors.

Moreover, it is easy-to-install. Take a knife and cut fiber Rockwool batts into a desired shape. You can fit them easily into place later on! It doesn’t settle over time and can seal all air gaps. It stays intact no matter how weather is outside. Just at times, you may need a vapor barrier to install on top of it for added efficiency.

The rockwool insulation can also block soundwave transmission, traffic or machinery noise revolving around your home! So, you can be peaceful staying at home. One can install rockwool insulation for music rooms, bedrooms, disco-party halls, etc. Rockwool blocks 10-15 decibels of sound with 1.7 pounds per cubic feet.

On top of everything else, it has a greater thermal performance that stays stable over a period of lifetime. It doesn’t easily degrade in its effectiveness. A one-time installation of rockwool insulation goes on for decades to come! It is corrosion-resistant and prevents decay effectively. Also, it cuts down on carbon footprints of homeowners! All these things make it perfect for wall insulation.

Though it seems a bit costly at times to many homeowners, architects, and builders, it is definitely worth its price!

Don’t miss:

What Insulation Has the Highest R-Value Per Inch
When do you need a vapor barrier for insulation
Spray Foam vs Fiberglass Insulation

R-values of other insulating materials compared to Rockwool

Type of Insulation Material

R value per inch of thickness


3.0 to 3.3 per inch of thickness

Foam Board

Up to 5.0 per inch of thickness


Between 3.2 to 4.0 per inch of thickness


Between 2.2 to 2.7 per inch of thickness

Wrapping Up

The R value of mineral wool insulation lies between 3.0 to 3.3 per inch of thickness. It facilitates extremely high thermal performance.

Because of its features like environment-sustainability, moisture-resistance, fire-resistance, recyclable and non-organic nature, corrosion-resistance, longevity, weather-resistance, ease-of-installation, sound-dampening properties, rockwool insulation is an excellent insulation option!

Don’t miss:

Rockwool vs Mineral Wool Insulation
Denim Insulation vs Fiberglass Insulation
Foam Board Insulation R Value Chart and Types

Needless to say, manufacturers use eco-friendly materials like basalt rock, steam, and slag while creating Rockwool. These planet-friendly raw materials keep our homes greener!

So, while you go for renovation things, you can go for rockwool insulation. You won’t regret your insulation decisions later!

Happy Reading! Keep Reading to discover informative pieces of contents!

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