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Can You Mix Blown-In Insulation Types?

Can You Mix Blown-In Insulation Types?

If you are looking for a simple way to make your home or other structure more comfortable without a colossal undertaking and without breaking the bank, adding insulation may be your answer. One question you may have is whether you may combine different types and materials when adding insulation to a structure.  

You can mix different types of blown-in insulation. Rather than removing and replacing previously installed material, you can blow in the same (or a different) kind of insulation to save money and time. You can also mix blown-in insulation with rolled fiberglass insulation instead of replacing it.

This article describes the most common types of blown-in insulation and when you should mix them. It also details the advantages of adding blown-in insulation to your previously installed material. Read on to learn more about the process of combining these insulation types and the benefits of doing so.  

What Is Blown-In Insulation?

Blown-in insulation is made up of tiny bits of fiber, foam, or other substances. These form an insulating material that is installed by blowing it into spaces. It is a good option for places where it would be challenging to fit different types of insulation, such as your attic and wall spaces.

What Types of Blown-In Insulation Can You Mix?

There are three commonly-used materials for blow-in insulation: loose-fill fiberglass, cellulose, and rock wool. All of these types of insulation are made using recycled waste materials that are blown in using special equipment. At times, they may be poured in instead. 

Loose-Fill Fiberglass

Most fiberglass is composed of 40% to 60% recycled glass. You can install fiberglass with a blowing machine.

This option is particularly suitable for attics and wall spaces as it is mildew-, fungus-, and moisture-resistant. 

Some critics say that loose-fill fiberglass can emit floating particles in the home because it contains recycled glass. However, when fastened with membranes or netting, particles are less likely to be a problem. 


This loose-fill material is chiefly made of recycled newsprint or corrugated cardboard. Cellulose has been used since the 1920s and provides an excellent sound barrier. It can cost less than $1 per square foot, making it a cost-effective choice for insulating materials. 

There are three types of cellulose used in homes: loose-fill, stabilized, and wall-cavity spray. Cellulose is an effective option for use in attic spaces because it contains a moisture additive and adhesive.  

Mineral or Rock Wool

Rock wool is usually produced from 75% post-industrial recycled content and is a popular choice for attics and wall and ceiling cavities. Traditionally made of rock, furnace slag, and other raw materials, rock wool is known for its fire protection qualities, and it is an excellent thermal and sound barrier.

These three materials are the most commonly used substances for blown-in insulation in homes and other properties. 

However, there are occasions in which a less common alternative may be used instead. Other types of loose-fill insulation materials include polystyrene beads, vermiculite, and perlite.  

Why Are Different Types of Blown-In Insulation Mixed?

Different types of blown-in insulation materials are mixed when a property owner adds to existing insulation using a new insulation material. This results in a mixing of insulation types. 

During new construction, batt insulation is often laid down and placed between wall studs and joists. When looking to add insulation, installing additional batts can be complicated and messy and would be work-intensive.  

A better option is to blow additional insulation into the attics and walls rather than cut and place batts on top of the preexisting ones. This process is less messy, quicker, and can save you money. Blowing in extra insulation can also seal small gaps and spaces as the material settles, keeping drafty air and excess noise out.

Source: Bob Vila

Benefits of Mixing Blown-In Insulation Types

There are many benefits of mixing different types of insulation rather than going through the complex process of cutting custom-sized panels or batts to add or remove and replace the existing insulation. These include: 

  • This process can give you better temperature regulation, which results in a cozier home.
  • Less stressful than removing and replacing old insulation.
  • It’s a cost-effective method of insulation.
  • Better insulation means lower energy bills.
  • Mixing insulation types will increase the lifespan of your existing insulation. It will also delay or stave off expensive replacement costs. 
  • Adding more insulation to your existing insulation can shield your home from outside noise.  
  • It is much easier to blow in a different type of insulation than to remove and replace the existing panels. Cutting and placing more batts in your attic and wall spaces can be tricky, and there may still be gaps left after you finish doing so. On the other hand, the small, blown-in particles cover all shapes and fit the crevices, providing comprehensive insulation coverage. 

Disadvantages of Mixing Blown-In Insulation Types

When combining different insulation types, you may encounter a few problems or difficulties along the way. These include: 

  • When blowing in additional insulation types, you will usually need to drill holes at the top of the stud spaces. These holes are usually at the exterior of the wall – that is, the side that you and guests to your home can see. Once you plug these holes, the plugs may be noticeable, which can ruin the aesthetic of your home. 
  • Obstructions in the wall may interfere with fitting the entire space with insulation, leaving a void where there is no insulation. These obstructions include things like an outlet box, drainpipe, or cross-board.


Your walls and attic spaces need to be properly insulated. Older homes may lack the amount of insulation required, or you may find that your insulation is no longer as effective. 

Trying to replace old insulation can be complicated, time-consuming, and expensive. Similarly, adding additional batt insulation is another challenging process. That’s where blown-in insulation comes in. 

Not only is blown-in insulation easier to install and more cost-effective, it also allows you to mix different types of insulation materials, allowing you to bring your home’s insulation up to speed as quickly as possible.

Recommended Reading:

What is the Building Envelope & How Does it Affect Insulation?

Insulation Around Furnace Exhaust: Important Do’s And Don’ts

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