Insulation is a crucial component of every home. Making the right insulation choice is vital whether you’re building a new home or think it might be time to install new insulation in your attic.

But when it comes to choosing between batts and rolls or blow-in insulation, homeowners have many misconceptions about the efficiency of different types of insulation.

Before deciding which insulation type is best for your home, you should consider the advantages and disadvantages of both blown-in and batt insulation.

Let’s discuss how blown-in insulation compares to batts and which insulation type is best for your particular case.

What’s Blown-In Insulation?

Blown-in or loose-fill insulation is loose material with a good R-value that is added to an attic floor or between stud and joist cavities. R-value is the industrial standard for gauging how well insulating materials resist heat flow; the greater the R-value, the better the material insulates.

Although many different materials can be utilized, such as styrofoam pellets or loose fiberglass fibers, cellulose material is the most common material for blown-in applications.

That’s how blown-in cellulose insulation looks.

Blown-in cellulose is made from recycled paper, cardboard, and other wood-based materials that are treated with boric acid and other chemicals to make it mold- and flame-resistant. 

During installation, a mechanical blower is used to distribute the cellulose. The blower uses paddles to loosen the material and combine it with air, then blasts the fluffy insulation through hoses to the desired location. A contractor is generally hired to complete this installation.

Blown-in is often regarded as the best method for adding insulation to pre-existing buildings — both for attic spaces and wall cavities.

Blown-in insulation advantages:

  • With the proper tools, installation is quick and simple.
  • Areas that are too narrow for batt insulation can be filled with blown-in insulation.
  • Blown-in can easily be added on top of existing insulation to supplement sparse areas.

Blown-in drawbacks:

  • Installing blown-in insulation is messy and often requires the help of a professional.
  • You’ll need to thoroughly air seal or install soffit venting before application.
  • Adding blown-in unevenly can cause the ceiling to sag in areas that are overfilled.  

What’s Batt Insulation?

Batt insulation or blanket insulation is made of fiberglass or mineral wool pre-cut into flat pieces. It either comes with a foil or paper (kraft) facing or without, and the need for facing is determined by climate and whether or not there is a vapor barrier.

Batt insulation can be used to insulate a home’s walls, floors, attics, and ceilings and is commonly laid between the studs, rafters, and joists. Because batt is relatively flexible, it can be used in framing to lessen heat transfer and lower energy costs.

mineral wool vs fiberglass insulation
Example of fiberglass insulation batts/rolls.

Batt insulation comes in various R-values and can be stacked to add more. Because batt does not settle and can also help with sound dampening, it maintains its effectiveness for years.

For optimum performance, batt insulation should be installed and fitted correctly.

Batt insulation advantages:

  • Installation is often less expensive than blown-in installation. 
  • Thermal protection is long-lasting.
  • Fiberglass batt is naturally fire resistant.

Batt insulation disadvantages:

  • Irregular spaces will require custom batt rolls.
  • Does not create an airtight seal without an additional barrier. 
  • Does not create a vapor barrier.

Blown-In vs Batts: R-Value Comparison (and Thermal Efficiency)

FiberglassCelluloseOpen-Cell FoamClosed-Cell Foam
Blown-In2.2-2.7 per inch3.2-3.9 per inch3.7-3.8 per inch7 per inch
Batt3.1-3.4 per inch3.2-3.8 per inchn/an/a

Batts or Loose Fill: Which R-value is Best?

R-value depends more on the insulation material rather than its form factor. For example, fiberglass batts offer higher R-values than fiberglass loose-fill insulation, yet cellulose blown-in insulation outperforms them both.

At the same time, it’s important to understand that both blown-in and batt insulation should be properly installed to achieve optimal R-value.

R-values per inch of thickness are used to calculate insulation ratings which describe how well the product can prevent heat from entering or leaving your home. The insulation’s material, thickness, and density all affect the R-values. Generally speaking, a house insulated with a greater R-rating will have better climate control and energy efficiency. However, a higher price tag is typically associated with better insulation R-values.

Remember that the R-value will differ depending on the type of insulation used, and vapor or radiant barriers do not affect the R-value. However, you may not need the highest R-value available when choosing insulation for your home. The R-value you need depends on the climate where you live. 

If you live in Florida, an R-value of R-13 may be sufficient. But if you live in northern Wisconsin, you may need something closer to R-60. These R-values are a sum, so when you add up the entire depth of the insulation, this will be the final R-value. For instance, if your insulation has an R-value of R-5 per inch of thickness, you will need to install a depth of 12-inches of this insulation in your attic to reach R-60.

If you don’t live on either end of the country’s climate spectrum, a good rule of thumb is an R-rating between R-13 to R-23 for exterior walls. The most commonly used R-ratings for attic spaces are R-30, R-38, and R-49.

Blown-In vs Batts: Installation Comparison

Both blown-in and batt can be installed in different home areas, including the attic and the walls. Purchased in pre-cut panels, batt insulation is frequently put in areas with few impediments such as pipes and wiring. It is commonly installed for new construction projects. A blowing machine is used to install blown-in insulation. The exact installation process may differ slightly depending on the material used.

Installing your own insulation is definitely doable, and you can save money by not hiring a professional. Installing fiberglass batt insulation is a simple DIY project. Blown-in generally requires the use of a professional.

Common Insulation Installation Errors 

You need to look out for three significant insulation errors: improper air sealing, compressed insulation, and gaps in coverage.

Adding insulation without air sealing won’t get you the benefits you are after. Ensure an air barrier is in place, and all leaks are sealed when you (or a professional) install your insulation.

Make sure that walls or other impediments like wires or outlet boxes aren’t considerably compressing your insulation. You won’t be getting the R-value level shown on the package with compressed insulation.

Leaving large spaces and gaps should also be avoided. Leaving just 1% of your attic space uninsulated can cause your insulation to be far less effective because of how heat flows through a space. 

Overall, if you are DIYing your insulation job, it is best to stick to batt. However, if you are hiring a professional, blown-in can be the more efficient option, especially if you have a lot of nooks and crannies in your home. 

Blown-In vs Batts: Costs Comparison

The thickness and density affect the price of batt insulation. For example, according to the U.S. Department of Energy, a 3.5-inch fiberglass batt has an R-value of 11 and costs between 12 and 16 cents per square foot. The high-density version has a 15 R-value with prices between 34 and 40 cents per square foot which is a significant additional expense for a comparatively little increase in insulating value.

A 12-inch fiberglass batt is at the top of the price and R-value spectrum. It costs between 35 and 60 cents per square foot and has an R-value of 38. The thicker batt is excellent for insulating the roof and exterior walls. The thinner batt is ideal for internal walls.

The majority of contractors don’t use the thinnest or thickest batts. The typical size for fiberglass batt insulation is 9.5 inches. According to the U.S. Department of Energy, this results in an R-value of 30 and costs between 39 cents and 43 cents per square foot.

Blown-in insulation is typically mixed materials and has an R-value per square foot that ranges from about 32 to 38. The R-value of loosely blown fiberglass alone ranges from 22 to 27 per square foot and is influenced by the blown depth and thickness. Blown-in insulation needs to be layered deeper and thicker in colder temperature zones which amps up the cost.

The cost of hiring a contractor and the quantity of filler required to determine the final price of installing blown-in insulation. You can expect to drop at least twice as much for blown-in installation charges as the typical price of batt insulation. You could save money on installation by doing it yourself. Still, this could complicate matters if you are not adept at drilling and mending wall holes. 

Insulation installation labor often costs $0.25 to $0.50 per square foot. The type of insulation, project size, location, labor costs, equipment, site preparation, and cleanup might cause pricing to vary from the national average. Certain insulation kinds need to be installed using particular tools. Spray foam, for instance, needs specialized equipment to install because it emerges as a liquid and hardens into foam. Due to the equipment and protective clothing required for the project, spray foam will likely cost extra.

Other Costs

The entire project’s cost will also include a sizeable amount for site cleanup and preparation. Any wall, attic, basement, or crawl space repairs required are considered part of the preparation process. Before a contractor can start installing insulation, a property could need mold remediation services if there is water damage or signs of mold or mildew. The cost of site preparation will depend on the size and repairs required. 

There can be an additional removal and disposal fee if the insulation expert needs to remove existing insulation. The average cost of removing the old insulation is between $1 and $1.50 per square foot without factoring in disposal fees. Fiberglass insulation batt removal is less expensive than blown-in attic insulation removal because the latter needs specialized equipment or a powerful vacuum to be removed.

To preserve a home’s energy efficiency, minimizing air movement is critical. Air sealing methods, such as air barriers, can stop leaks into and out of a house. To stop erratic air movement, air barriers create pockets. By employing weatherproofing strips and caulking, they prevent leakage inside and outside. A house wrap is another method for sealing the air. To stop airflow, a house wrap is formed of fiber plastic and wrapped around the exterior of a house. Since it is far simpler to adopt home air sealing techniques during construction than during home retrofit, that is often what happens. Depending on the dimensions and complexity of the project, air sealing can cost anywhere from $350 to $600.

The R-value of most insulation gradually decreases, necessitating replacement. Replacement insulation for the majority of blown-in insulation costs between $2 and $7 per square foot. Remember that stiff foam boards are often the most straightforward to remove. A professional will fill the space with the new insulation after the old insulation has been removed, sealing and patching the area.

Overall, batt insulation tends to come out cheaper.

Blown-In vs Batts: Safety Comparison

The safety of your insulation depends on what material it is made from. Fiberglass insulation has a long history — not all good. It’s known to cause skin irritation, incite allergy symptoms, and exacerbate asthma. However, although fiberglass is fire-resistant rather than fireproof, fiberglass insulation still has almost no fire hazard attached to it (making it a popular choice in places that often deal with wildfires.)

Spray foam is undeniably made from toxic chemicals — some of which pollute the indoor air. Once applied, it’s tough to remove, creating toxic dust in the process, which is dangerous to those working on the removal process. As for fire, spray foam insulation will ignite at 700°F even though it’s heavily treated with fire-retardant chemicals prior to installation.

Although it is paper-based, cellulose insulation doesn’t make your house more flammable. To comply with legal safety criteria, cellulose insulation is treated with fire retardants such as ammonium sulfate, borax, and boric acid. Since cellulose insulation has a Class 1 Fire Rating, it can aid in limiting the spread of fire. 

Blown-In vs Batts: Common Applications

Blown-in is excellent for filling in tight areas around wiring, pipes, or any spot with awkward framing. Batt insulation is great for an expansive area with little to no obstructions where no prior insulation is in place.


The optimal insulation for attics can’t be determined in a “one size fits all” manner because some variables are involved. Batts are perfect for large, uninsulated attics with few to no barriers and plenty of headroom for the insulation contractor to work in because they cover such a large area. However, blown-in may be a better option if the attic is cramped or oddly shaped.


Due to their high amounts of dampness and colder temperatures, basements are difficult to work in. The secret to effectively insulating basement walls is choosing insulation materials that block moisture flow and inhibit mold development.

The best type of insulation for moist environments like basements is spray foam. Spray foam with a closed cell structure is ideal for “locking out” water vapor that naturally seeks to go from moist basement walls into finished basement rooms.

Crawl Spaces

Homeowners are often unaware of the significant influence that crawl space insulation has on a home’s energy efficiency. 

Installing fiberglass batt insulation between the crawl space’s exposed joists was the traditional method of insulating crawl spaces, as fiberglass is more accessible and less expensive than other forms of insulation. However, its propensity to absorb moisture, foster the growth of mildew, host rodents, droop, or otherwise deviate from its intended position are all drawbacks that make it inappropriate for use in crawl spaces.

Rigid foam insulation board is the ideal type of insulation for crawl spaces. The crawl space foundation walls serve as the foundation for the foam board, which is laid there instead of between the floor joists. In contrast to fiberglass, rigid foam insulation does not absorb water, support mold, or permit air to travel through it.


Due to the garage’s connection to your building, it will be possible for outside air to enter your home through the shared wall. Insulation becomes even more crucial if you have a room added above your garage.

The most common insulation material used in garages nowadays is probably fiberglass. It includes rolls that will be precisely sized and stapled into a wall or ceiling cavity.

Yet, spray foam has the best air sealing properties, energy efficiency, durability, lifespan, and R-value of any garage insulation option. It is also the most expensive at the same time.

Can You Combine Blown-in and Batt Insulation?

Installing fiberglass batts over your current blown-in insulation is not problematic. The only thing you need to ensure is that the insulation you use is “unfaced,” which means the batts don’t have a paper or aluminum foil facing. You can peel the facing off of faced batts or buy the batts fully unfaced, which is simpler and less expensive.

This precaution is necessary because the insulation batts’ facing acts as a vapor barrier to stop moisture vapor from entering the insulation. When facing insulation is added atop blown-in insulation, the vapor barrier is basically sandwiched in the middle between the two layers of insulation.

Any vaporized moisture that enters your ceiling would likewise pass through the blown-in material before hitting the batt’s face, where it would be confined. That has the potential to damage the framing members as well as the insulation, and mold growth is also a possibility.

In fact, you can even mix different insulation materials together, such as mixing cellulose and fiberglass, as long as you follow the necessary installation precautions.


Justin's been in construction for over 20 years in both new build and renovation. With experience in both commercial and residential construction, he specializes in healthier and more energy-efficient homes.

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