What Is Rockwool Insulation? Your Go-To Guide

We've all heard of fiberglass insulation and cellulose insulation. But a lesser-known insulation material on the market is rockwool insulation, and it just might be the perfect insulation for your home—especially if you’re wondering how to soundproof a room. Let’s break down what rockwool is to see how it compares to other insulation options available.

What Is Rockwool?

Rockwool is a type of insulation that is commonly used to insulate residential buildings. Also called stone wool insulation, rockwool is created through a heating process that melts two key materials together. One ingredient is rock-based minerals derived from basalt or diabase rock, while the other ingredient is recycled slag. Slag typically comes from the byproducts of iron ore blast furnaces.

As the two materials heat, they spin together, like a cotton candy machine, until the melted droplets create fine fibers. From there, the fibers are taken to be used as insulation or to serve other purposes. A hydraulic press contorts the fibers into insulation for an easy installation.

What Is the Percentage of Recycled Material in Rockwool? 

Just how much rockwool contains recycled materials depends on the manufacturing facility, but you can expect your rockwool to contain anywhere from 16% to 40% recycled goods on average. 

Pros and Cons of Rockwool Insulation

Rockwool insulation comes with many advantages and disadvantages that make it a bit of a controversial insulation material. Below are the pros and cons of choosing rockwool insulation to help you determine if it's the right material for your home. 

Benefits of Rockwool Insulation 

Let's start with the advantages of rockwool insulation. You’ll find that rockwool has many pros that make it a top contender for many home insulation projects. Here are some of the benefits of rockwool:

• Uses recycled materials

• Provides excellent soundproofing

• High R-value

• Serves as a poor heat conductor, which traps heat inside insulated buildings

• Has fire-resistant qualities

• Moisture resistant

• Mold- and mildew-resistant

• Easy installation

• High durability

Disadvantages of Rockwool Insulation

With all the advantages that come with rockwool, the insulation does have a few cons that you should consider before choosing this type of insulation material—namely, the potential health risks associated with rockwool. Check out these disadvantages of rockwool before you invest in this insulation.

• High cost

• High pH level

• Can irritate the skin, eyes, and respiratory tract 

• Loose fibers can harm your lungs and could be a possible carcinogen

• May also cause itchiness 

• Won’t biodegrade

How Much Does Rockwool Cost?

Rockwool insulation costs anywhere from $1.10 to $3.10 per square foot, depending on the quality of the insulation, the insulation’s R-value, and whether you install it yourself or hire a pro. This high cost puts rockwool up there in the ballpark of the cost of spray foam insulation.

How to Install Rockwool

Installing rockwool insulation is a simple and straightforward project because the material is semi-rigid batt insulation. Rockwool does not come in loose-fill or blown-in insulation types. This means that the material is both flexible and firm enough to easily place inside your wall panels, attic space, crawl space, floors, basement, or other areas without professional assistance.

To install rockwool, measure the size of the space you’re installing the rockwool, put on a complete personal protective equipment assembly, cut the material to size, then insert the rockwool into the areas you want to insulate.

Though installing rockwool is a fun project for avid DIYers, it’s not for everyone. If you’re looking to quickly install rockwool without so much as lifting a finger, you can always work with a professional insulation company near you to complete your installation.