Spray Foam Insulation vs. Fiberglass: What's the Difference?

How do you choose the right insulation for your home? You start by knowing the differences between each type and how those differences affect you. For example, spray foam insulation versus fiberglass—each option has its pros and cons. Here's how to choose the best one for your home.

Spray Foam Insulation vs. Fiberglass Insulation: Key Differences

The major differences between spray foam insulation and fiberglass insulation are the cost of insulation, R-value, and the insulation installation process. Spray foam insulation has a higher cost and more complicated installation process than fiberglass. However, it's also less prone to water damage and has a higher R-value.

What Is Spray Foam Insulation?​

Spray foam insulation starts out as a liquid that expands and hardens into a rigid foam when sprayed into an enclosed space.

Best for: 

• Homeowners looking for a dramatic reduction in heating and cooling bills.

Pros of Spray Foam Insulation

Spray foam insulation does a great job of keeping heat out of your home. It has a higher R-value, the measure of protection against heat transfer, than fiberglass. That means it'll keep the warm air indoors in the winter and the hot air outside in the summer. The result? Lower heating and cooling bills for you.

Since it helps to reduce your home's energy costs, spray foam insulation has a good return on investment (ROI). It can also give your home's value a boost. Spray foam insulation also has a long life and can last anywhere from 80 to 100 years. 

Cons of Spray Foam Insulation

It's not perfect, and there are some problems with spray foam insulation to be aware of. One major drawback is the cost. Spray foam insulation costs more than fiberglass, averaging $2,885 for the entire house.

Also of concern for eco-conscious homeowners is the environmental footprint of spray foam. It's made from polyurethane, a petroleum-based product, and isn't renewable. Producing spray foam material can also produce chemicals that are environmentally harmful. Finally, the installation process for spray foam insulation can be complicated.

What Is Fiberglass Insulation?

Fiberglass insulation comes in several forms, including batts, boards, and blown-in insulation.

Best for: 

• Budget-conscious homeowners

Pros of Fiberglass Insulation

Fiberglass insulation is much more budget-friendly than spray foam. The cost of fiberglass insulation ranges from $0.30 to $1.50 per square foot, compared to $1 to $2 per square foot for spray foam insulation.

It's also available in more forms than spray foam, ranging from blown-in insulation to batts or rigid boards. Whether you choose batts, boards, or blown-in insulation, the installation process is much simpler and something you can DIY.

Similarly to spray foam, fiberglass insulation can last for many years if properly installed and not exposed to moisture or humid conditions.

Cons of Fiberglass Insulation

Compared to spray foam insulation, fiberglass insulation can experience moisture damage. If the material gets wet, it can clump together and lose its insulating properties. Depending on how much humidity or water gets on it, you may need to replace fiberglass insulation. 

Fiberglass insulation also has a lower R-value than spray foam, meaning it may not be as effective in areas with very cold winters or very hot summers. 

Finally, there are some potential dangers of fiberglass to be aware of. If you disturb fiberglass, it can release particles into the air, which can irritate your lungs if inhaled. Some people also experience skin or eye irritation if they come into contact with the material. If you're going to handle fiberglass insulation, always wear long sleeves, gloves, goggles, and a mask.

Spray Foam vs. Fiberglass Insulation

Take a closer look at spray foam versus fiberglass insulation to see how each one stacks up in several categories. 

Options and Customizations​​: Fiberglass

Fiberglass insulation comes in multiple forms, from batts to blown-in, making it potentially easier for you to find a format that works in your space and with your budget. Spray foam, on the other hand, is either available in open-cell or closed-cell, with closed-cell insulation offering the higher R-value.

Durability​​: Spray Foam

Under ideal conditions, both fiberglass and spray foam insulation will last for decades. But spray foam is the winner here because it's less susceptible to moisture damage compared to fiberglass. 

Price​: Fiberglass

With a lower cost per square foot and a lower installation cost overall, fiberglass is the clear winner. The cost of installing fiberglass batts or blown-in insulation is similar, though you may find that installing batt or board insulation is a lot simpler.

Ease of Installation: Fiberglass

Fiberglass insulation has a relatively simple installation process, with many handy homeowners feeling confident enough to tackle installing fiberglass batts or boards on their own.  If you're going to go the blown-in route, your best bet is to work with a professional insulation company, which will have the right equipment and know-how. 

Eco-Friendliness: Fiberglass

If you are concerned about the environmental impact of the materials used in your home, fiberglass is the better bet than spray foam insulation. The primary ingredient in fiberglass insulation is glass, a natural material made from sand. Spray foam is made from polyurethane, which is created from petroleum. 

ROI: Spray Foam

Spray foam may have the highest price tag of all your insulation options, but it also potentially offers the highest ROI. Installing spray foam insulation can lead to a significant drop in your energy bills, thanks to a reduced need for heating or cooling. Over a few years, your energy cost savings may make up for the amount you spent up front. 

R-Value: Spray Foam

Spray foam insulation creates a tight seal in your home's walls, giving it the highest possible insulation R-value. Thanks to that higher R-value, spray foam also has a high ROI.

Fiberglass insulation can also have a decent R-value, but it can also lose some of its effectiveness over time. As blown-in insulation settles, it doesn't block heat transfer as well, for example.