Fiberglass VS Foam Insulation Comparison: Pros and Cons

The fiberglass vs. foam insulation debate is a recurring subject of discussion in structural insulation. While fiberglass has long been a popular choice for insulation in many homes, foam insulation is the latest entrant triggering the buzz.

Foam insulation has a superior R-value to fiberglass insulation. Fiberglass insulation excellently resists water. But while closed-cell foam insulation is impressively water resistant, its open-cell counterpart isn’t. Fiberglass and foam insulation are commendably durable. Economically, fiberglass is cheaper than foam insulation.

But can foam insulation really unseat fiberglass as the preferred material for installing attic insulation among homeowners? To properly respond, it is necessary to compare foam and fiberglass insulation in more detail. What are they exactly? What distinguishes them from one another?

Pros of Fiberglass Insulation

First, let’s consider fiberglass insulation. What makes Fiberglass insulation stand out?

• It’s effortless to install

Installing the fiberglass batts is relatively easy. Due to its popularity, manufacturers produce it with the same width as the typical space between wall studs. This makes it as easy as just unrolling and stapling them.

It’s both fire and moisture resistant

Fiberglass can become moist or wet. Thus it isn’t completely waterproof. However, it easily dries off and neither holds nor retains water. In extension, this prevents mold from growing on it.

Additionally, fiberglass is non-combustible. This is because it is made from a glass and sand mix which are both fire-resistant materials.

• It is eco friendly

For those concerned about the environment, you need not worry about the impact of fiberglass insulation on the environment. This is because the two main components, glass, and sand can be recycled.

• It is inexpensive

Fiberglass’ price points seem like a steal when putting all its qualities into consideration. You can purchase it anywhere from $1 to $2 per square foot.

Cons of Fiberglass Insulation

Now let’s look at the deterrents to using the fiberglass insulation.

• Fiberglass sags with time, causing a decline in its R-value

• If formaldehyde is used as a binder during installation, it can cause cancer if inhaled.

• Also, the tiny glass particles can get loose with time and get carried by air. This can cause respiratory issues if inhaled.

Pros of Foam Insulation

Now let’s consider the advantages of foam insulation.

It is durable

Foam insulation is made of two components: isocyanate and polyurethane. Once sprayed and hardened, it retains its performance for a long time. In addition, it does not expand, therefore, does not deform. So, you are guaranteed durability.

• Installation is also easy

Though professionals best handle installation, there isn’t any rocket science activity to be done. The process is just for the professionals to mix the necessary chemicals and then spray them onto your desired area using a spray gun.

Airtight seal

The spray insulation provides an airtight seal. This prevents moisture from seeping through.

In addition, insects and rodents will have a hard time finding their way through. In addition, this airtight seal traps in the air, protecting you from drastic weather changes and saving you energy bills.

• It provides extra strength to the building

When the foam insulation hardens, it becomes dense and acts as a kind of glue, gluing the building materials together. This quality suffices as an extra layer of strength to the building.

Cons of Foam Insulation

What are the drawbacks to installing Foam insulation?

• Foam insulation is costly. You have to hire a team of professionals to install it for you. Also, the price will increase in tandem with the size of the space to be sprayed. This price can start from $1,500 to $4000.

Even if you want to do it yourself, you will have to purchase the chemicals, spray guns, and other necessary materials, which all cost a lot of money.

• The chemicals used here can cause allergic reactions if it touches the skin or is inhaled.

Alright, let us extensively analyze foam and fiberglass insulation side by side in the following critical aspects.


The R-Value of an insulation material connotes its thermal efficiency against external factors. The higher the R-Value, the higher the insulation quality of the material.

The Fibreglass insulation R-Values vary by type. These types include the Batt, Attic, Wall, and Rigid Fibrous. However, the range is from 2.2 to 4.3 per inch.

On the other hand, foam insulation is of two types, and they have their own R-Value range. The Open-Cell foam insulation is less effective, with an R-Value range of 3.5 to 3.6 inches. Its alternative, the Closed-Cell foam insulation has an R-Value range of 6.5 to 7 per inch.

Resistance to Moisture

Fiberglass insulation does not absorb or hold water and thus won’t degrade over prolonged exposure to this moisture. However, it does not do this alone.

This quality is made possible due to substances known as vapor barriers. This is typically made of polyurethane. It is placed over the insulation face to prevent moisture from accessing the insulation and getting into the walls or surface.

Naturally, open-cell foam insulation is not moisture resistant while its counterpart, Closed-Cell foam insulation, is.

Nevertheless, the moisture-resistance quality of the foam insulation depends on the density of the foam.


Both Fiberglass insulation and foam insulation are very durable and can even last for a century too, given the right conditions. For Foam insulation, the Closed-Cell insulation has an edge due to its higher R-Value.

However, certain mitigating factors can reduce its lifespan. These include over-exposure to the elements like water and extreme weather conditions. Others include puncture and stress caused by objects leaning against the surface.

It is advisable to do a home evaluation and change the installation if you notice certain anomalies like consistent allergic reaction, pungent smell as a result of dampness, elevated energy bills, and uneven temperatures.

Ease of Installation

Fiberglass insulation can be done either by a professional or as a DIY project. Whatever the type of fiberglass used, it usually comes in a structured form resembling thick blankets. Holes are then cut out in them for electric outlets and carefully placed in the wall cavities. You can also opt for blow-ins to get a more secured fitting.

After placing them in their cavities, vapor barriers are also installed for moisture resistance and to further hold the installation in place. This involves sealing the face with materials such as polyurethane or plastic sheets. The last process is to staple on the wall facing.

On the other side of the divide, Foam installation is much easier but is best handled by experts. This is because it requires mixing certain chemicals in the right quantities. Afterward, the mixture is then sprayed unto the surface using a spray gun.


Fiberglass insulation is the cheaper of the two costing less than $2 per square foot. Installing it yourself will further reduce costs, while hiring the services of a professional can cost up to $70 per hour.

If you have a deeper pocket, then you can go for the Foam insulation. This is way costlier, with prices rising up to $4,000, labor inclusive.

Health Effects

Both insulation types are capable of having effects on the health, especially when incorrectly installed.

First, handling fiberglass without protective clothing can cause skin irritation. When touched with bare hands, the tiny but sharp glass strands can cause cuts deep enough to draw blood.

Furthermore, the composite materials, glass, and sand can get loose in the long run and get carried by air. If inhaled, it can cause respiratory issues, allergic reactions, and even cancer.

In the same vein, foam insulation can also be toxic to health. The chemicals used can trigger allergic reactions if inhaled.

Also, since foam insulation guarantees a tight seal, if the foam used is too much, this can result in poor air quality as moisture gets trapped, providing a safe location for the growth of microbes and mold in the room.

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