A closeup of fiberglass insulation in a wall

When researching types of insulation, fiberglass is likely one of the main types you will come across. However, each variety of insulation has its own characteristics—the most important being cost and R-value. 

This article focuses on fiberglass insulation, including a breakdown of its types, average cost, and an in-depth analysis of the R-value. This information will help you decide if fiberglass insulation is the best option for your home and, if so, which type. 

What is the R-Value of Fiberglass Insulation?

The R-value for insulation is assigned to tell you how efficient the insulation is. The higher the number, the more effective the insulation. Depending on the type of fiberglass insulation you use – batt, attic, or wall – the R-value can range from 2.2–4.3 per inch. 

Types of Fiberglass Insulation

There are several types of fiberglass insulation to choose from when purchasing. Some are better for specific areas of your home, so it is essential to know what kind of fiberglass insulation you want to invest in. For example, if you are only looking to replace or install insulation in an attic, it may be different from installing insulation in walls. 

Manufacturers make fiberglass insulation by spinning very fine strands of glass into layers or small particles depending on the type. This insulation has a lifespan of about 50 years and is known to be cost-effective. 

Batts

Insulation batts are long rolls of structured insulation. Very fine layers of fine glass strands make up batts insulation. It looks like a very thick blanket. To install this type of insulation, simply measure it off the roll and put it in place.

Fiberglass insulation being installed in the underside of a home attic ceiling, showing a beige fiberglass batt

It has form and structure, unlike loose-fill insulation. Fiberglass batt insulation fits into walls perfectly and comes in various depths. You can either hire a contractor or install this insulation yourself. 

Loose-Fill  

On the other hand, loose-fill insulation is not structured or in any form. Retailers sell it in bags, and you can install them nearly anywhere. Homeowners and contractors install loose-fill insulation in both attics and walls. This type of insulation has flexibility in its installation location. 

It is essential to be careful when installing loose-fill fiberglass insulation. Because the insulation is in small particles, it is easy to inhale them. Inhalation is very hazardous, and you should wear proper personal protective equipment.

A picture of a man blowing in loose-fill fiberglass insulation onto an attic floor.
Technician spraying blown Fiberglass Insulation between Attic Trusses foam insulation repair tool in the white protect suit applies a construction foam from the gun to the roof.

Usually, after installation, builders place a mesh fabric over the insulation to prevent movement. Typically, a professional conducts the installation for large areas and uses a blower to spread the material evenly. 

Rigid Fibrous or Fiber Insulation

This type of fiberglass insulation is highly specialized. It is only used for ducts or other areas that withstand incredibly high temperatures.

The only real benefit of fiberglass rigid fibrous or fiber insulation is that it can withstand high temperatures. HVAC contractors typically use this during their work installing ducts. 

Fiberglass Insulation R-Value by Type (with Chart)

Here is a breakdown of fiberglass insulation by type and the respective R-value. 

Type of InsulationR-Value
Batts3.1 to 3.4 per inch of thickness
Loose-fill (attic)2.2 to 4.3 per inch of thickness
Loose-fill (wall)3.7 to 4.3 per inch of thickness
Rigid Fibrous4 to 5 per inch of thickness

Cost of Fiberglass Insulation

Fiberglass insulation is a cost-conscious option for our home. The price runs between $0.40 and $0.50 per square foot. In addition, you can install batt-style fiberglass insulation as a DIY project, making it even more affordable. 

Contractors usually install loose-fill fiberglass insulation using a blower, a specialized piece of equipment. So while loose-fill insulation is technically cheaper than batt-style insulation, the costs end up evening out in the long run when you factor in installation costs. 

Installing batt ceiling or attic insulation in a 534 square foot area costs between $944 and $1502. This figure includes time, labor, materials, equipment, and any additional job supplies needed.

If you want just to buy the insulation itself, the price will run between $680 and $896. Other costs to your project might include removing existing insulation or disposal of materials on the job. 

For comparison, the cost of installing loose-fill fiberglass insulation in a 534 square foot area is between $621 and $1,061. The materials alone cost between $264 and $617.

Installation time is approximately four hours and must be installed by a professional. Therefore, hiring contractors for installation is the majority of the cost. Additionally, contractors’ contracts typically do not include the removal of existing insulation or the disposal of materials. 

Where to Buy Fiberglass Insulation?

*This section contains some affiliate links so that if you are planning to buy some fiberglass insulation, we’ll earn a small commission, which helps keep the blog going.

The easiest and most readily available place to buy fiberglass insulation is a store like Home Depot or Lowes.

As of this writing, they have two main options, both of which are good depending on what R value you’ll need and how much space you have to fill in.

Home Depot's listing of a roll of R-13 fiberglass insulation

The first is a Kraft (paper) faced R-13 fiberglass roll that comes in different sizes. You can see those here.

Home Depot's listing of a roll of R-30 fiberglass insulation

The second is a Kraft (paper) faced R-30 roll that is more expensive, but you get the much higher R-value. You can see those here.

Installation Differences

Contractors install the two types of insulation in different ways.

Batt fiberglass insulation comes in long rolls and is very easy to install as a DIY project. To install, simply purchase the thickness you need for your project, then cut the insulation to the desired length.

You can then place it wherever you need. Batt fiberglass is great for inside walls because it is easy to set and does not typically clump or slump over time. 

Homeowners typically hire contractors to install loose-fill fiberglass insulation. Proper installation requires specialized equipment, including a blower and a mesh lining that lays over the insulation to prevent it from moving. Retailers sell loose-fill fiberglass insulation in bags. 

For both types of insulation, if you want a higher R-value, install the insulation thicker. Thicker is not always possible in walls, but it can be done relatively quickly in attics. 

Health and Safety

Fiberglass as a material is incredibly effective and durable; however, it can irritate the skin if touched and is potentially harmful to your lungs if you breathe it.

Therefore, when installing fiberglass insulation, it is critically important to wear appropriate gloves and a face mask. Additionally, it is practical to wear long sleeves and pants. 

Conclusion 

Fiberglass insulation does not have the highest R-value on the market, but it is one of the most cost-conscious options. The R-value for fiberglass batts ranges from 3.1–3.4 per inch of thickness. For loose-fill fiberglass insulation in an attic, the R-value is 2.2–4.3 per inch and for the wall is 3.7—4.3 per inch. 

Batts fiberglass insulation is excellent for walls and can be used for attics. Loose-fill fiberglass is the opposite. It can be used in walls but is ideal for attics. Both are great  insulation options  without breaking the bank. Batt-style insulation makes a great DIY project, while a professional should install loose-fill. 

No matter who is installing your insulation, it is crucial to wear proper health and safety equipment to prevent irritated skin, eyes, or lungs. 

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