Blown In Attic Insulation – Everything You Need to Know

Blown In Attic Insulation

Attic insulation is key to controlling your home temperature throughout the year. Heat naturally collects in your attic, making your house cooler or hotter depending on the season.

Blown-in insulation is one of the most effective ways to insulate your attic. In this article, we’ll discuss blown-in attic insulation, its pros and cons, and the different types of insulation on the market to help you properly insulate your attic.

Key Takeaways

  • Blown-in attic insulation is a type of insulation made of cellulose, fiberglass, or similar materials that are thick, dense, and lumpy in consistency.
  • The “blown-in” aspect refers to using a special machine to insert the insulation into parts of the attic.
  • Blown-in attic insulation helps retain warm air inside the home during winter and prevent heat from entering during summer, leading to reduced energy consumption and cost savings.
  • Pros of blown-in attic insulation include the ability to fill small spaces, low cost, and protection against insects and vermin.
  • Cons of blown-in attic insulation include the need for professional installation, the potential for ceiling sagging if too much insulation is used in one area, and proper sealing and ventilation to prevent mold and rot.
  • There are two main types of blown-in attic insulation: cellulose and fiberglass.
  • Cellulose insulation is made from recycled paper and has an R-value of 3.5-3.8, while fiberglass insulation has an R-value of 2.2-2.9 per inch and is often the cheaper option.

What is Blown-In Attic Insulation?

What Is Blown In Attic Insulation?

Blown-in attic insulation refers to cellulose, fiberglass, and other thick, dense, and lumpy insulation. It has a consistency similar to that of down feathers and can fit in tight areas such as walls or between wires or ducts.

Blown-in insulation used in homes is made from various materials, such as recycled newspaper, cardboard, glass, and common waste.

The “blown-in” aspect refers to using a special machine to “blow” insulation into parts of your attic. You’d typically buy a larger block of insulation, insert it into the machine, and fill in any spots that need to be insulated.

Benefits of Blown-In Attic Insulation

Benefits of Blown In Attic Insulation

Blown-in attic insulation keeps warm air from escaping your home during the winter. It also prevents heat from entering your home during the summer.

There are, however, more benefits to blown-in attic insulation that homeowners should be aware of:

  • Insulation retains warm air generated by your heater in the winter while keeping heat out of your home during the summer. This means your AC and heater units will work significantly less, saving you on your energy bills
  • Certain types of insulation, like fiberglass are completely fireproof
  • With a proper blower, installation is simple and quick
  • Fiberglass and cellulose insulation can also soundproof your attic
  • Blown-in insulation can reduce condensation by controlling your attic temperature
  • Blown-in insulation gets into tighter nooks and crannies within your attic

Blown-In Attic Insulation Pros and Cons

Blown In Attic Insulation - Pros and Cons

While there are clear benefits to using blown-in attic insulation for homeowners, key advantages and disadvantages are important to consider.

Let’s explore some of the pros and cons of blown-in attic insulation here:


  • Blown-in attic insulation can be inserted in areas that are too narrow or small for rolled-up batt insulation. It can fill the space between heaters and AC units in your attic to keep them properly insulated and make the best use of your attic’s space.
  • Purchasing insulation used for blown-in purposes is inexpensive but doesn’t compromise the R-value or the insulation’s resistance to conductive heat flow.
  • Insulation is often treated with borates that prevent insects and vermin from populating your attic.
  • Blown-in attic insulation can also easily be layered on top of existing insulation or bolster already insulated areas.


  • Unless you’re an experienced contractor, installing blown-in insulation can be messy and often requires you to call a professional.
  • If you put too much insulation in one area can cause the ceiling to sag.
  • You’ll need to air seal and install soffit venting if needed thoroughly.
  • If you’re blowing cellulose over existing fiberglass, you may need to cut and refit poorly laid batts and insulate plumbing first.
  • Blown-in insulation can succumb to mold and rot if it comes in contact with a lot of moisture over an extended period—which is why it’s important to ensure the area is sealed before blowing.

Types of Blown-In Attic Insulation

Types of Blown in Attic Insulation

Now that we know the advantages and disadvantages of blown-in attic insulation, let’s take a look at the two types of insulation that homeowners typically use to insulate their attic – cellulose and fiberglass:

Cellulose insulation

Cellulose insulation is made of recycled paper and is an economically-friendly option for homeowners. It also contains the chemical borate, which makes it both fire and insect-resistant.

Cellulose insulation has about a 3.5 to 3.8 R-value. It won’t settle too much if you apply it correctly, meaning if you blow in about 10 inches of cellulose insulation, it’ll stay at 10 inches longer.

While cellulose insulation is mainly irritant-free, we recommend wearing safety gloves and goggles when blowing it into your attic.

Fiberglass insulation

Another popular blown-in attic insulation material is fiberglass. It’s often the cheapest insulation option between the two. It has an R-value of about 2.2 to 2.9 per inch.

Some fiberglass insulation contains as much as 53% recycled glass, which has the added benefit of not settling too much after it’s been installed. It also prevents it from catching fire, making your attic fire-safe.

Best Blown-In Attic Insulation

So which material should you choose for blown-in attic insulation?

We recommend fiberglass for blown-in attic insulation for its lower cost and effectiveness. While every home has different needs, this is the most versatile option.

We also recommend the Johns Manville Formaldehyde-free™ fiberglass insulation as the best fiberglass option. It provides thermal and acoustic insulation for your attic, perfect for vertical and horizontal applications.

The Johns Manville fiberglass insulation is available in R-values to fit any home specifications. It’s perfect for covering tight spaces, small gaps, or voids. It’s fire-resistant, thermally efficient, and won’t settle after installation.

As the name suggests, Johns Manville’s fiberglass is free of formaldehyde and can even soundproof your attic when applied tightly. It won’t corrode into wires or metal studs and is just as fire-resistant as other insulation materials.

How Much Does Blown-In Attic Insulation Cost?

How Much Does Blown In Attic Insulation Cost?

At this point, you might be asking: how much will all this cost?

This is a tough question since your blown-in attic insulation budget depends on a few factors. These include:

  • The State you live in since R-values vary by location
  • The size of your attic and which areas need insulation
  • The general climate around your home
  • The material you ultimately choose to insulate with
  • Labor and professional equipment costs

Home Advisor estimates that installing blown-in attic insulation costs anywhere from $1,000 to $2,500 for about 1000 square feet of attic space.

The average home should need an R-value of about 30, which means 10 to 14 inches of total insulation.

Is Blown-in Attic Insulation Worth It?

Yes, blown-in attic insulation is generally worth it for several reasons:

  • Improve Energy Efficiency: Blown-in insulation helps prevent heat loss in the winter and heat gain in the summer, reducing the strain on your heating and cooling system. This can result in lower energy bills and a more comfortable indoor temperature.
  • Increase Comfort: Insulating your attic helps regulate the temperature in your home, reducing the likelihood of hot and cold spots and making it more comfortable to live in.
  • Increase Home Value: Insulating your attic can increase your home’s energy efficiency, making it more attractive to potential buyers and increasing its resale value.
  • Reduce Noise: Insulating your attic can also help reduce outside noise, making your home quieter and more peaceful.
  • Protect Your Home: Insulating your attic can also protect your home from moisture damage, reducing the likelihood of mold and mildew growth and helping to preserve the structural integrity of your home.

Based on all these benefits, the cost of purchasing and installing blown-in insulation is often outweighed by the long-term benefits.

The only instances where it may not be worth it are when the existing insulation in the attic is sufficient and does not need to be replaced or supplemented, and additionally if the homeowner is planning to move soon and will not be able to realize the long-term benefits of the investment fully.

It’s important to consider factors such as the age and type of the home, climate, and current energy bills to determine if blown-in attic insulation is a worthwhile investment. A professional energy auditor or contractor can provide a more personalized assessment.

Budgeting for Blown-in Attic Insulation

So, what will your budget look like for installing blown-in attic insulation?

You first need to look up the recommended R-value your attic needs to meet. This determines the insulation you purchase and how much you’ll need to cover your home sufficiently.

Then, it would be best if you looked at the cost of labor for installing blown-in attic insulation.

If you need professional experience and equipment for this project, we recommend hiring a qualified contractor or insulation company to handle the work.

Get an Attic Inspection

We recommend you get an attic inspection before buying all the materials and hiring a contractor.

You never know what potential issues or considerations are hiding in your attic. Chances are, you don’t visit your attic all that often. This means there could be various issues ranging from poor air sealing, ventilation problems, and poor air quality.

Attic inspectors can identify these types of issues. They’re also there to show you the insulation you’ll need based on several factors.


How often should blown-in attic insulation be replaced?

Blown-in attic insulation typically lasts for a long time and does not need to be replaced as frequently as other types of insulation.

However, the replacement frequency depends on various factors, such as the type of insulation material used, the climate, the ventilation of the attic, and the presence of moisture or mold.

On average, blown-in insulation can last for 20-30 years. Still, it’s always a good idea to inspect your attic periodically to ensure that the insulation is in good condition and performs its job effectively. If you notice any moisture damage or mold growth signs, you may need to have your insulation replaced sooner.

Is blown-in insulation cancerous?

Blown-in insulation is not considered carcinogenic, but some materials used in the production of insulation, such as fiberglass and mineral wool, can release small particles into the air that can be inhaled and potentially harmful to your health.

It’s important to take appropriate safety measures when installing insulation, such as wearing protective clothing and a mask, to minimize exposure to these particles. If you have concerns about the safety of insulation in your home, it’s best to consult a professional or seek advice from your doctor.

Is blown-in insulation a fire hazard?

Cellulose insulation is often blown in and is a recognized fire hazard by the Consumer Product Safety Commission (CPSC). It can burn when exposed to something burning, and improper installation can be a severe threat.

Can you put too much blown insulation in your attic?

It is possible to put too much blown-in insulation in your attic.

If the insulation is packed too tightly, it can restrict airflow and reduce the effectiveness of your ventilation system. This can lead to a buildup of moisture, which can cause mold, rot, and other damage to your roof, attic, and home.

It is important to follow the manufacturer’s recommended guidelines for the proper insulation depth in your attic and to consult a professional if you have any questions.


Stop unwanted heat transfer and build an energy-efficient attic. Leverage this article to know everything you need before embarking on your blown-in attic insulation project.