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How Do You Install Rockwool Insulation on Walls?

man installing thermal insulation rock wool under the roof

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A comfortable house is necessary for the better growth and development of every human being. And proper temperature plays a significant role in keeping the home comfortable.

This is where insulation plays a key role. Insulation stops temperature from entering or leaving the house. It prevents heat from escaping in winter similarly; it doesn’t allow heat to enter the house in summer. 

We spend a lot of time indoors, so, naturally, we use so many energy-consuming appliances to maintain a good temperature inside the house. But when we insulate our house, we save a lot of energy consumption. It reduces your heating or cooling cost.

We can find numerous insulation materials available in the market these days and Rockwool insulation is very much in use. It has a higher insulating value than other commonly used insulations like fiberglass.

What is Rockwool insulation?

Rockwool is a type of thermal insulation made by spinning or drawing actual rocks and minerals after heating them to their melting point, with added mineral oil which makes them water repellent. 

The melting point of Rockwool RWA45 insulation is so high that they are often used to prevent the spread of fires in buildings.

The fibers that make Rockwool insulation are good conductors of heat, but by the time it is pressed into roots and sheets, it becomes a poor heat conductor. Meaning it is now able to block heat. Rockwool reduces the transfer of sound waves, making it a good fit to reduce noise pollution.

Rockwool or Mineral wool has fire-resistant properties. It repels moisture, but at the same time, it is vapor permeable. If the insulation becomes damp, it will still maintain its original performance characteristics when thoroughly dried. There is no chance for mold to grow because Rockwool products are inorganic and cannot be a food source.

 Professional worker in overalls working with rockwool insulation material


Installing mineral wool is not a big deal. 

If you’re planning to install the Rockwool insulation on the wall for the first time, then make sure you measure all the areas that need to be insulated and then cut the Rockwool accordingly.

However, if you’re adding the insulation over the old one, make sure the previous insulation isn’t squashed or sagged. Installing new insulation gives better and even results.

Follow the steps carefully while installing the insulation.

  • Start by placing the Rockwool batt at the top of the stud bay and then tuck it in so that it is flush with the stud. It helps to maintain its efficiency. Be careful while stuffing the Rockwool because you don’t want to smash it down, otherwise, it will ruin the R-value.
  • You can cut your batt using either a drywall knife, handsaw, or a standard bread knife. Cut the size as per the requirement, get the measurement right.
  • There should be no gap in between the batts and the top and bottom of the stud bay. You want the batt to fit tight. So while cutting the bat, cut it 1 to 1 ½ inch extra so that the Rockwool fits tight and improves the energy efficiency
  • Tuck in the pieces properly.
  • Now, if there are pipes in your stud bay, what you do is you get the measurement from the edge of the pipe to the edge of the stud and then transfer the measurement to the Rockwool. After that, cut out a groove the same width as the pipe into the Rockwool, remove about one-half of the insulation.
  • It is best to fit the Rockwool in the center of the stud bay because the pipe has a little bit of flexibility, and you can slide it up into the bay.
  • And if there are wires, you need to handle them differently. Just observe the wires and cut a groove into the Rockwool, as per its direction. Now place the batt into the stud bay so that the wire fits into the groove.
  • Electrical boxes need to be handled differently again. You get the measurement of where the electrical box is, then cut out the section of Rockwool so that the Rockwool fits nice and snug to the box.


  • Rockwool is made up of rocks and minerals and other recycled steel slags, which makes it durable.
  • The quality of Rockwool insulation remains good for a long period, it does not rot or allow mold to grow on it.  
  • It has a higher r-value for the same thickness than other institution materials like fiberglass. This means Rockwool insulation has higher heat resistance as compared to other competitors.
  • Rockwool can repel water and doesn’t absorb the moisture, which keeps the material in good condition for years.
  • It is fire-resistant. The melting point of Rockwool insulation is so high that the chances of catching fire don’t exist, and they are often used to prevent the spread of fires in buildings.
  • You can easily install Rockwool insulation by yourself, cut it an inch bigger and tuck it properly, that’s it.
  • Rockwool is so dense that it reduces airflow, making a room soundproof to some extent.


  • Rockwool is non-biodegradable. You throw it away, but it remains on earth forever, making it non-environment friendly.
  • It is costlier than other commonly used insulation.

Final Thoughts

Rockwool insulation is easy to work with. But it is always recommended to wear protective gloves, masks, and other safety equipment while dealing with the insulation. You better wear full sleeves because your skin itches when it comes in contact with any insulation.

Rockwool is a bit costlier, but you’ll make the cost within a couple of years because it has long-term durability. Your home will be well insulated for years to come with little maintenance needed.

A properly insulated house keeps us calm and relaxed. After a long hectic day, home is where we return, our mind and body require a comfortable space. Insulation maintains a comfortable environment.