Spray Foam or Fiberglass: What is Better For Insulation

Published On: January 16, 20221 Comment on Spray Foam or Fiberglass: What is Better For InsulationTags: Last Updated: February 3, 20244.1 min read

I’d like to discuss the differences between spray foam and fiberglass insulation. Spray foam is more beneficial than its counterparts for a number of reasons, I’d have to say.

Spray Foam or Fiberglass

Here are a few reasons:


Spray foam insulation has higher R-values than fiberglass insulation. Fiberglass is not watertight so it can let moisture in and also cracks. Spray foam insulation, however, does require professional installation. R-value is a term used to measure thermal resistance. One of the main factors in determining how well a material can insulate, it is considered an essential consideration before making a decision as to which insulation would be best suited as the type of insulation material for your home.

The higher the R-value, the better you will be protected from heat escaping. The R-value for fiberglass can range from 11 to 38, with 11 for 3.5-inches (8.89 cm) thick and 38 for 12-inches (30.48 cm) thick fiberglass. Spray foam insulation typically has an R-value of between 3.8 per inch and 7 per inch so it’s worth checking which type you have. This means that for a 3.5 inches thick insulation material, you get R-values of 13.30 and 24.5, respectively, by either using open-cell or closed-cell spray foam.

In comparison, both foam types provide a value of 42 in R-value when you purchase them in 17.78 cm size. Taking this in mind, spray foam is the better option when compared with other insulation materials. It has higher thermal resistance which in turn results in superior thermal performance

Better and longer lasting insulating

The long-term costs of spray foam are not substantially higher than fiberglass. Spray foam lasts longer and provides better insulation, so it’s worth the investment if you plan to stay in your house for at least 5 years. One of the reasons many homeowners choose to use spray foam installation is because it’s an effective way of reducing monthly energy bills. With the average American household spending over $1,000 on their electricity and natural gas bill, using spray foam insulation can save you hundreds every year. Spray foam insulation has a ton of benefits. It seals any gaps and inhibits air leaks, leading to better overall efficiency per square foot than traditional fiberglass insulation.

Moisture Resistance

Insulation materials need to do well in moist environments. If you have walls close to the ground, like in basements or garages, they will be more vulnerable to these kinds of issues. Fiberglass is sensitive to moisture and will tend to crack when exposed to it. It can’t dry out completely so it won’t be exposed to this issue nearly as often as other materials. Spray foam insulation, on the other hand, is better at resisting moisture damage than fiberglass. So if you live in a humid climate, spray foam may be right for you.

No problems with critters

It can be hard to keep these rodents out of your insulation depending on the product you used. Mice and rats will chew through any insulation that’s made from fiberglass or that has holes in it like straw or nylon. What you should do instead is spray foam insulation, which won’t have any food sources or nesting materials for rodents.

Spray Foam or Fiberglass - fiberglass insulation

Better air quality

Molds can survive in moist conditions. With spray foam insulation that limits condensation and prevents air infiltration, there is less risk of mold growing and better air quality.


Spray foam and fiberglass insulation both have a long lifespan, but their age varies. Spray foam will last for over five decades while fiberglass could last up to two or three decades. Fiberglass insulation will sag over time, whereas the foam insulation will shrink. However, both types of insulation should last you another 30 years before needing to be replaced again.

Fortified structures

One of the less-known benefits of spray foam insulation is how it strengthens your walls, making them more rigid and less likely to fail.

Flood resistance

FEMA reports that AP building materials below the BFE (Base Flood Elevations) must be flood damage-resistant. The expected or historic flood duration does not matter. FEMA recommendations state that only Class 4 and Class 5 materials are acceptable for areas below the BFE (base flood elevation) in SFHAs (special flood hazard areas). One of the few insulation materials rated as highly as Class 5? Spray foam.


Mixed opinions about fiberglass and spray foam installation aside, they are the go-to when it comes to insulation. They have a number of benefits that you might not be aware of – just make sure you hire a professional installer to help! Clearly, those who want to live a greener lifestyle and decrease their carbon footprint should consider using fiberglass insulation. Products are composed of renewable materials that are capable of being reused or recycled when the product reaches its end. Spray foam insulation is a more suitable option for those who live in hot and humid areas.

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  1. Victoria Addington November 20, 2023 at 4:39 am

    My spouse recently constructed a shed, and he is in need of shed insulation. It’s fortunate that you pointed out that spray foam insulates well and lasts longer. It looks like a wise investment; therefore, I will absolutely let him know about it. I’ll also look into experts that can help us install one. Thanks for sharing!

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