Spray Foam vs Fiberglass Insulation: The Differences That Matter

If the temperature inside your home or your office starts to change drastically with the weather, you may have a severe problem at your hand. If you have to rely constantly on your heater and air conditioners, you are most likely suffering from the lack of thermal insulation.

There are many advantages to installing insulation materials to your home: the stable temperatures inside your home that aren’t affected by external temperatures by much, the decrease of energy bills due to less usage of heating or cooling devices, fire resistance, and acoustic soundproofing, etc.

It is very normal, especially for beginners, to get overwhelmed by picking from all the different insulation solutions one is provided with. There are countless insulation materials and combinations of them that can be used to achieve different insulation levels.

In this article, we will discuss some of the most used insulation materials, namely Spray foam insulation and fiberglass insulation, see their key differences, and analyze their merits and demerits to make an informed decision.

Spray Foam vs Fiberglass Insulation

Difference Between Spray Foam and Fiberglass Insulation

One needs to consider many key metrics in insulation before choosing between the two, including R-values, resistance to fire and moisture, durability, STC rating, etc. Both fiberglass and spray foam insulation is extensively used in the field, yet there are differences in their types and insulation level.

Fiberglass is mainly available in two different forms, including batts and loose forms. Batts constitute blanket-like material that can be cut to fit our needs. On the other hand, loose-fill fiberglass contains loose pieces similar to pillow stuffings. This can be blown into the walls using a blowing machine, and one can achieve a higher level of thermal insulation due to the compact packing.

Let us closely look at some of the key differences between fiberglass insulation and spray foam insulation.


Spray Foam


Ease of Installation

It is hard to install and may require a professional set of hands.

It is relatively simple to install and can be done without any expertise in the area.


3.8 to 7 per inch

2.2 to 3.8 per inch

Resistance to moisture content

Spray foam is watertight and impervious to moisture content.

Fiberglass doesn’t hold well against moisture content and can retain it for some time.


It can easily last over 50 years if taken good care of.

High durability and can last more than 50 years.

Cost of Installation

More expensive

Relatively Cheaper solution

Harmful effects

Not many side effects if installed correctly. Poor installation can result in unwanted risks, including irritation in the skin, eyes, lungs, etc.

Safe to use if installed correctly. Incorrect installation can lead to the inhalation of thin glass fibers and cause problems for the lungs.

Even though the installation mode varies greatly for fiberglass insulation and spray foam insulation, they are both excellent insulators. They can provide you with stable temperatures compared to the outside environment.

Spray Foam Insulation

Spray Foam Insulation

Spray foam insulation is a widely used insulation solution. It is made of a chemical in the liquid foam that is sprayed with the help of a can, and once it is sprayed, it expands over the cracks and voids of the surface, creating an airtight layer.

Spray foam insulation comes in two forms: open cell and closed cell. Spray foam is sprayed over a surface, and it later expands and sets into place, creating an airtight, watertight seal with amazing insulation properties.

  • Open Cell: In the open-cell spray foam, the foam cells are not fully enveloped, and hence the foam appears to be soft and is flexible.
  • Closed Cell: The foam cells of this spray foam are completely closed and pressed against each other, and they are more rigid, stable, and dense than the open cell form.

However, there is a downside to closed-cell spray foam solutions, and it is costlier since they are much more effective than their open-cell counterparts.

Now, let us look at the merits and demerits of spray foam insulation in detail.


  • It provides powerful support and a higher level of insulation to the homeowners.
  • It can bring down the energy costs of the building by blocking the outer environment temperature and keeping the inner ambiance stable.
  • It also provides an airtight, water-resistant seal that is strong.
  • It has a long lifespan and can typically last as much as the house if taken care of.
  • It is an environment-friendly insulation solution.
  • It can provide structural support to your walls and the roof in addition to wall insulation and attic insulation.


  • Spray foam insulation doesn’t fill every crack and cavity and can leave out spaces.
  • If not installed correctly, it can cause water damage to the home.
  • There is a possibility that spray foam insulation can start shrinking and cause a drop in the efficiency of the insulation.
  • It requires a professional to install it correctly.

Fiberglass Insulation

Fiberglass Insulation

Fiberglass is one of the most used insulators and is especially known for its thermal and acoustic resistance. They are essentially made of glass fibers that are available in different forms. There are mainly two types of fiberglass insulation available, and they are Batt fiberglass insulation and loose-fill fiberglass insulation.

Batt Fiberglass Insulation

The name itself is suggestive of this form of insulation. Spun, molten glass is layered up to get a thick batt or blanket of fiberglass, and it is rolled up to be used at homes.

The R-value of such insulation can vary according to the thickness of the blanket used and the number of layers of fiberglass blanket used for insulation. One can double or triple the layers of fiberglass insulation for higher efficiency.

Loose-Fill Fiberglass Insulation

Loose-Fill Fiberglass insulation is a more recent development and has higher insulation efficiency. These contain small fiberglass particles and can be inserted inside walls using a blowing machine.

This type of fiberglass insulation is best suited for existing buildings and renovation projects. But, the installation of such insulations requires a professional and can prove to be expensive.

Now, let us look at the pros and cons of fiberglass insulation, in general.


  • Batt insulation of fiberglass has one of the easiest installation procedures, and it can be done without any professional help.
  • It has very good moisture resistance.
  • The material is non-combustible and provides fire resistance.
  • The materials used are eco-friendly and can be recycled.
  • It costs less and is an economical solution for everyone considering insulating their home.


  • Improper installation of fiberglass insulation can reduce its overall efficiency.
  • Comparatively speaking, fiberglass insulation has a lower efficiency overall than other insulation methods in the market.
  • Insulation material requires a lot of processing in factories during manufacturing, and hence can contribute to air pollution

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Spray Foam Insulation Vs. Fiberglass Insulation: Head-to-Head Comparison


Spray Foam Insulation: Spray foam insulation is available in two different forms: open and closed cells. These differ in the rigidity and softness of the end material after installation. Open Celled spray foam insulation results in a flexible and soft surface of the insulation, whereas in closed cell spray foam insulation, the cells are arranged more compactly and hence are more rigid and stiff.

Fiberglass Insulation: Fiberglass insulation is mainly available in two forms; batt insulation and blown-in insulation.

Batt insulation, or blanket insulation, makes use of fiberglass blankets or rolls that are manufactured by layering pieces of fiberglass over a conveyor belt. These are made into rolls and can be cut as per the client’s requirements.

Blown-in or loose-fill insulation contains a loose fiberglass material mixture blown into the wall using a blowing machine. These provide higher compactness to the insulation and can provide higher efficiency.


Spray Foam Insulation: Spray foam insulation has a higher R-value with over 3.8-7 per inch. Higher R-value is desired for an insulation solution as it quantifies the ability of a material to prevent heat flow.

Fiberglass Insulation: Fiberglass insulation can provide only up to 2.2 to 3.8 per inch, which is comparatively lesser than spray foam insulation. However, the efficiency of thermal insulation can be improved by using blankets of higher thickness or by using high-quality material.

Life Expectancy

Spray Foam Insulation: Spray Foam Insulation has a life expectancy of over 50 years and can be considered a long-term solution. It is also resistant to water and can survive long if good care is given.

Fiberglass Insulation: Fiberglass insulation is also a long-term solution and can easily last as long as the house itself, extending well over 50 years of operable life.

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Spray Foam Insulation: Spray foam insulation has higher values and has a complex installation, and thus it costs more than that fiberglass insulation.

Fiberglass Insulation: Fiberglass insulation is one of the cheapest insulation solutions available in the industry and is readily available as blankets and loose-fill form.

When to Use Spray Foam Insulation

Spray foam insulation is a versatile insulation solution. Even though it is costlier than fiberglass insulation, it makes up a higher R-value, has higher packing efficiency, and can reach irregular and hard-to-reach surfaces.

Spray foam insulation is best suited for surfaces with irregular angles that can’t be reached using foam or fiberglass panels.

When to Use Fiberglass Insulation

Fiberglass Insulation can be used with both fresh construction projects and renovation projects. These can provide structural rigidity to the home and is one of the most economical solutions available.

If you have a fresh construction project with exposed walls, it might be better to go for batt insulation, and for renovation projects, one can consider blown-in or loose insulation. This is because we don’t need to separate the wall to place the insulation for wall insulation and attic insulation with blown-in insulation. A hole can be drilled in, and with the help of a blowing machine, the cavity can be filled.

What is cheaper, Spray Foam Insulation or Fiberglass Insulation?

Fiberglass Insulation is cheaper than spray foam insulation in terms of material and installation costs, and fiberglass insulation is one of the most economical insulation solutions available. However, fiberglass’s R-value and other insulation properties are less than that of spray foam insulation.

Both are very good choices and provide cost-effective solutions to your home’s temperature problem in terms of value for money spent on wall insulation and attic insulation.

What Is Better Spray Foam Insulation or Fiberglass Insulation? The Verdict

Both spray foam insulation and fiberglass insulations are versatile products and advantages.

  • Spray foam insulation is a long-lasting insulation solution made of a chemical that can even insulate hard-to-reach places. It has high R-values and other insulation properties compared to fiberglass insulation and can provide you with a stable temperature in your home. The only downside to the insulation method is its cost, which is more than fiberglass insulation.
  • Fiberglass Insulation is one of the most used insulation solutions, and it can be used as batts and loose-fill forms. It is easy to install, cheap, cost-effective, and long-lasting, and it is better suited for fresh construction projects with exposed walls.

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In this article, we have discussed the key differences between spray foam insulation & fiberglass insulation and analyzed each of their merits and demerits. We have also provided insights into what to look for while searching for insulation to help you make an informed decision when it comes to your home.

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