One of the most common debates in the world of attic insulation is the question “spray foam insulation or fiberglass?” While fiberglass has been a regular go-to staple insulation in American homes for many decades now, spray foam is the new kid in the neighborhood creating all the latest buzz.

But does spray foam have what it takes to dethrone fiberglass as the ideal choice among homeowners?

Let’s look what fiberglass and spray foam insulation are and their differences.

What is Fiberglass Insulation?

Fiberglass insulation

Fiberglass Insulation Material

Fiberglass is a sequence of exceptionally delicate fibers that consist of several recycled materials, largely, melted down glass.

These glass fibers are commonly held together by adhesive backing that serves as a moisture barrier such as reflective aluminum paper or foil.

Affordable but definitely efficient as an insulator, fiberglass is utilized by approximately 85% of American homeowners today.

How is Fiberglass Packaged?

Fiberglass is available for purchase in the following two forms: batts and less common blown-in loose-fill.

Here’s a closer look at both:

Batts –They’re very easy to pick up at the store and carry upstairs, and once they’re unrolled, they’re able to cover a ton of space. Batts are often designed to be the precise identical size as the regular spacing between studs on attic walls.

The only problem with batts is that, in attics that have either weighty obstacles on the ground and walls or feature difficult spacing, batts must be cut exactly to size.

Loose-Fill – Fiberglass is also available for buying in bags as loose-fill material, that comes in large lumps. Fitting this loose-fill fiberglass in your attic requires a professional installer using a huge puffing machine to blowout the fiberglass wherever necessary.

Blowing in loose-fill fiberglass is an excellent choice for homeowners who live in older buildings with previous insulation in place and numerous obstructions in the way, as it’s impeccable for filling in the tight spaces around pipes and wiring that batts fight to cover.

Since the blowing machine eradicates the necessity for maneuvering around the room during installation, loose-fill insulation is also a leading choice for any attic with a tight space and low ceiling.

What is Spray Foam Insulation?

Spray foam insulation is a liquid chemical that comes out of a spray can and inflates to create an airtight closure over cracks and any other spaces that air could flow through.

How is Spray Foam Packaged?

Spray foam is packaged into two forms:

Spray Foam Insulation in South Florida

Installing Foam Spray Insulation

Open Cell – This refers to foam composed of cells that aren’t fully enclosed, which makes the foam both elastic and soft.

Closed Cell – As the name suggests, this is foam with cells that are entirely closed off. These cells merge with one another to block the channel of air and vapor.

Between the two, closed cell foam is certainly the better insulator, particularly in attics where space is tight. Additionally, its moisture-resistant qualities make it an excellent moisture barrier that’s impermeable to water damage.

The disadvantage with closed cell foam is that, since it’s expressively more capable than open cell foam, it’s obviously much costlier.

Key Differences Between Fiberglass and Spray Foam Insulation


R-value is the measurement utilized to decide an insulator’s effectiveness in resisting airflow. R-value is a simple “the higher, the better” statistic.

On paper, spray foam is the clear winner in this category, as closed cell foam can reach an R-value height of up to 7.0. It also doesn’t sag or settle over time, a side effect that fiberglass insulation suffers from when it’s installed incorrectly.

Nonetheless, fiberglass is no slouch at blocking airflow either, as specially designed medium and high-density fiberglass has R-values as high as 4.3.

Resistance to Moisture

This category is a neck-and-neck race. Both spray foam and fiberglass are adept at resisting moisture.


In attics that can maintain ideal conditions, fiberglass insulation will last for a remarkable 100 years. Spray foam, on the other hand, will tap out at about 80 years.Spray foam insulation doesn’t sag or settle as fiber glass

The Installation Process

Using a blowing machine is easier even for the DIY type.However,using batt is not a simple process to hack. On the hand, the spraying process is complicated even for experts. If installed improperly, there are chances that it could lead to dire consequences.


Both spray foam and fiberglass insulation are fire resistant and have soundproofing benefits.


Fiberglass insulation is more affordable and will save you money in the short term. Spray foam insulation installation is relatively costly but will save you money in the long-run.

References and Resources