Spray Foam Insulation Cost vs Fiberglass

Kenneth Wilson

Home insulation is one investment every homeowner would need in the long run. But, while many homeowners favor various insulation materials, spray foam and fiberglass are the most popularly used for home insulation. Spray foam is designed with isocyanate and a polyol resin, while fiberglass is built with a plastic figment coupled with glass to make the fiber. 

With these two insulating materials scaling the industry, a lot of people fear purchasing either of them. If you’re considering getting an insulator for your home, this article will set the best cost comparison guide as we focus on spray foam installation cost and fiberglass. 

What Is Spray Foam Insulation?

Spray foam insulation is unlike any other insulation material as it is woven with polyol resin and a form of isocyanate. When sprayed onto a surface, these compounds undergo a chemical reaction and expand. Then, it quickly hardens within seconds to get you that airtight seal you desire around your living area.

Spray foam has a longer lifespan and can be applied in regions not suitable even for fiberglass. This material has a higher energy efficacy and eases the stress of having to pay higher utility bills. Spray foam installation consists of two types; closed-cell spray foam and open-cell spray foam. 

Open-Cell Spray Foam Insulation

As the name suggests, this type of insulation comprises cells that are broken or intentionally left open to fill the gaps inside the material with air. Unlike closed-cell spray foam, open-cell is softer and less structurally taut. Rather, the cells in this insulator take a cohesive structure. Open-cell spray foam is budget-friendly and does not really need a solid shape to function.

Closed-Cell Spray Foam Insulation

Closed-cell spray foam insulation implies a method where its cells are completely closed. Unlike its open-cell counterpart, it has a relatively high density as the closed cells are filled with gas making them structurally stronger and a better insulator. Closed-cell spray foam works effectively for regions that require high air and water insulation and structural support. Aside from this, it is quite expensive. 

Let’s consider some other features of both spray foam insulation types in the table below. 

Open-cell Spray

Closed-Cell Spray Foam


Has a limited insulation range it weighing between 0.4 and 0.5 lbs/cubic ft


Varies greatly in density, which is as high as 1.7 to 2.0 lbs/cubic ft

Installation Process

Easy to apply and install using a water-based process

Installation Process

Require the proper R-value conductors and blowing agents for installation. Hence, they are more difficult to install


Usually low-cost


More expensive

What Is Fiberglass Insulation?

Fiberglass insulation is a lightweight composite material that consists of a plastic matrix and is strengthened by a significant amount of glass fibers. The good thing about this insulation is that you can either reduce it into batts or blown directly into any region you want to insulate within your home. 

How Does Insulation Work?

Insulation focuses on how heat flows, especially in your home. To understand how insulation works, you want to consider three factors: conduction, convection, and radiation.


Conduction deals with the way heat move within a material. Imagine placing a metal spoon in a hot bowl of water and how it feels when the heat envelopes the container only to pass through the handle and get to your hands. In conduction, the heat circulates through anything in its gas or liquid form. 


Convection helps to dispel dense and cool air while rising the warmer and lighter air in your home.


In radiation, heat flows in a straight line, and when it comes in contact with anything solid, it heats the object while easily absorbing the energy. Understanding these factors will put you on the right track to achieving a well-insulated living area. But, while this is important, you also want to know how the installation process works. 


Fiberglass insulation has an easy-to-install build that requires little to no training. So, if the installation cost seems quite disturbing, it will please you to know that this insulating material works exceptionally even with the DIY route. However, you want to make sure to get the best Recommended Personal Protection Equipment (PPE) such as gloves, long sleeves, protective goggles, and a dust mask.

Apart from this, installing fiberglass insulation will require no downtime. This is because it does not need a curing or drying time. You even enjoy safely engaging in other trades during the installation process. 

Spray Foam

Spray foam insulation does not offer this amazing installation advantage, as it creates downtime and requires you to vacate the job site during installation. When completed, it is recommended to wait between twenty-four to forty-eight hours before re-entering the building. Why? It takes time for the spray to work.

You also want to avoid the DIY route as this procedure requires expertise and precision. This is because spray foam insulation will demand you mix two hazardous chemicals, and without the proper expertise, you may end up risking your health. 

For this reason, it is best to hire a professional that has gone through an intensive training program with the Occupational Safety and Health Administration (OSHA) or the Spray Polyurethane Foam Alliance (SPFA). 

Like the fiberglass installation method, you also want to purchase the right Personal Protective Equipment (PPE) including full-face supplied-air respirators and protective clothing for harmful chemicals. 

While this method works efficiently, it poses a fire outbreak, especially when unprompted combustion occurs due to a lack of precision and exothermic reaction in the installation process. Apart from this, it may cause adverse health issues, especially when not mixed and applied properly.

Benefits of Home Insulation

Home insulation offers a large range of benefits to homeowners. However, the major advantage attached to insulation is that it slows heat flow. While most insulating materials slow down the conductive heat, spray foam and fiberglass insulation slow both the conductive and convective heat.

No matter the location or angle heat moves, these insulating materials create a vacuum to help heat flow from warm to cold until the temperature evens out. Some other benefits home insulation offers includes: 

  • Saves you the cost of paying monthly energy bill as it restricts the flow of heat
  • Help prevent warm air from entering and escaping your home
  • It prevents the formation of ice dams on your roof as this can cause significant roof damage.
  • It keeps temperature and control systems at their peak. 

What Impact Does Either Options Have on the Value of Your Home? 

Home insulation is one of the significant technical home upgrades that increase the value of every home in the market today. So, installing either fiberglass or spray foam insulation will hold a huge impact on the market value of your home. However, fiberglass insulation night has a lesser impact when you look at the amazing benefits closed-cell spray foam insulation offers you. How? The simple answer is hinged on quality. 

A type of spray foam insulation called closed-cell insulation has a higher R-value because of the unique market benefit it offers. Some of these benefits include heightened structural strength, pest resistance, mold resistance, and low-priced maintenance cost. Let's find out more about the R-value of either insulating method. 

How Do R-Values Fit in Home Insulation?

When it comes to home insulation, one factor to always look out for is the measure of the insulating material to resist conductive heat. R-value refers to the ability of a material to resist heat flow when faced with different elements and test conditions. In essence, the higher a material's R-value is, the more operational it functions as an insulator. 

R-value is perhaps the largest indicator of the longevity, quality, and functional capacity of the insulating material. The R-value of your insulator will depend on the density, ability to absorb moisture, longevity, and thickness of the insulating material. Apart from this, location also plays a huge role in the effectiveness of the R-value. 

While many experts opine that spray foam insulation has a higher heat-resistant capacity, many opt for fiberglass insulation due to its affordable and low-priced nature. But, which of these options functions more effectively as an insulator? 

Spray Foam Insulation R-value

One of the most popular used insulation for both residential and commercial buildings in the industry today, this insulation has been observed to have the highest R-value per inch. This is apparent in one of its types called closed-cell spray foam insulation, which by far has the highest ranking in the market today. This type of insulation has an R-value ranging from R-6.5 to 7 per inch. Closed-cell spray foam insulation adds to the structural strength of your roof, ceiling, and walls due to its high density and glue-like adeptness. 

On the other hand, open-cell spray foam has an R-value of R-3.5 to R-3.6 per inch, which means it can fill a 2×4 cavity and yield about R-13. An exceptional advantage of this insulator is that it never diminishes in efficacy. 

Fiberglass insulation R-value

While spray foam works exceptionally as an insulator, fiberglass functions more like cellulose as it may lose its R-value over time. Fiberglass insulation types like batts and batteries have an R-value ranging from R-3.0 to 3.4 per inch, while blown-in fiberglass has its R-value at R-2.2 to 2.7 per inch. 

Does Cost of Both Options Dictate Longevity? 

One other factor to consider when evaluating both fiberglass and spray foam insulation is its lifespan. Did you know that an insulator with a short lifespan will easily damage and might demand a high cost of replacement?

While many homeowners get lured with the choice of purchasing low-cost insulation to save money, it does not necessarily work that way. Getting a cheap and inferior quality insulating material could make you invest in frequent repairs than an expensive and long-lasting one. So, the simple answer to this question is yes, cost plays a significant role in how long your insulator lasts. 

Apart from this, the lifespan of your insulator varies depending on the conditions of the location installed and the expertise used in its installation. Spray foam insulation is highly durable, does not deteriorate easily not does it lose its R-value quickly. If installed properly it may even last as long as your house stands. 

Fiberglass insulation on the other hand may last between eighty to a hundred years when installed properly. However, they are more likely to damage earlier than expected. This is because unlike spray foam insulation z they are not waterproof and get easily damaged by excess moisture. Hence, you may spend more on the cost of replacement every fifteen to twenty years. 

Estimating Insulation Costs

Insulation cost differs on the amount of insulation you may need. For spray foam insulation, many contractors tally insulation price by the board foot, which means that insulation costs will depend on how wide, thick and long they are. A board foot measures 12inches long, 12inches wide, and 1inch thick. If you're considering getting insulation for your home, you want to first determine the available square foot in your home by the board footage. Then, multiply the depth by inches. 

Another factor you want to consider when making your estimates is the R-value of your insulation. The R-value will tell you how effective and capable the insulation is at resisting heat. In essence, you measure how well your insulator will function in the insulating space. A higher R-value will usually range from R6, R7, R13, and higher.

In addition, you want to multiply the R-value for every installed insulation layer. So, if you get a product that has an R-value for R6 as 1”, applying 2” will give you R12 and 3” will offer you R18. 

When estimating the cost of fiberglass insulation, one factor unique to this material is that it can either be faced or unfaced. Faced insulations come as rolls or batts, while the unfaced are usually blown-in. So, how much will spray for insulation and fiberglass insulation cost? 

Cost of Spray Foam Insulation

Spray foam insulation costs three times the amount of fiberglass insulation, meaning they are more expensive. However, they help you save more on cooling and heating costs. The average cost for spray foam insulation may range between:

$3.95 to $7.20 

per board foot

  • When measured per board foot, the average cost of open-cell foam insulation ranges between $0.45 to $0.80.
  • On the other hand, the closed-cell spray foam installation may range between $1 and $2 for every board foot.
  • Depending on the built and quality of the product, the average cost may range between $3.95 and $7.20 per square foot.

Cost of Fiberglass Insulation

Unlike spray foam insulation, fiberglass insulation is relatively cheaper to apply and install. Depending on the quality, the general cost for fiberglass insulation may include:

$1.65 to $3.40 

per board foot

  • The cost of getting this material may range between $0.45 to $0.75 per board foot.
  • Installation cost averages between $1.25 to $2.65 per board foot.
  • Total installation costs will range between $1.65 to $3.40 per board foot. 

Determining Insulation Cost by Location 

Before getting your insulating material, you want to know that the area you wish to insulate also plays a major role in determining the average installation cost. Consider the following;


Oftentimes, attics usually come in smaller sizes with large windows that facilitate intense temperature within your home. This is why keeping a well-insulated attic is important, especially during the cool summer and warm winter climate. With proper insulation, you easily achieve this without having to run your HVAC system at all times.

So, when considering insulating your attic, you want to consider the price. Averagely, the insulation cost for the attic will depend on how wide the room is and the material type you will use. But, total insulation cost may range between $1000 t0 $2000. 

Crawl Space

Another factor to bear in mind is that moisture does not work well with insulation. So, insulating a crawl space that allows moisture to seep in may be bad for insulation. For this purpose, it is important to keep a well-ventilated crawl space before considering installation. Fiberglass installation methods like batting work best for this type of location with the average cost ranging between $100 and $300 depending on size and area. 

Garage Door

If you’re considering going the DIY route, then you want to try using spray foam installation. This process is more efficient and allows your garage door to function well. For a 9inches garage door, the average cost usually falls between $150 to $200. 


For roof insulation, it is best to go the professional route. Why? You will have to make sure that the roof vents are properly sealed with no gaps in them. For professional roofing insulation, you want to make financial plans between $1000 and $1500 depending on the board foot and the expertise. Spray foam insulation is a good choice for this area. 


While different materials can work effectively for insulating any wall surface, blown-in insulation will be the best choice for aged walls, like the drywall. On the other hand, batt installation works exceptionally for newly built walls. If you're considering the do-it-yourself method, you want to first cut a hole into the wall, then blow in the insulator before sealing p the hole. To carry out this process cost, the total cost may range from about $1 per square foot. 


As a homeowner, insulation is one investment you want to consider because it keeps your living area free from the harsh climate. However, this would only suffice depending on the effectiveness and quality of the insulating material used. 

Fiberglass insulation is one of the cheapest ways to keep your home well-insulated, unlike the more expensive spray foam insulation. However, it is less effective, especially when faced with extremely cold conditions. They are mostly used in 85% of American homes and even favors the DIY route.

On the other hand, spray foam insulation has less market share due to its complexity and expensive nature. But, it is increasingly growing in popularity today. To properly install spray foam insulation, professional installation is required. 

Frequently Asked Questions

How much will it cost me to insulate a 12 by 12” room?

If you are considering using spray foam insulation, the total cost for this type of living area ranges between $3.20 to $9 per square foot. 

Is insulation worth the cost?

If you are considering using spray foam insulation, the total cost for this type of living area ranges between $3.20 to $9 per square foot. 

Do spray foam and fiberglass insulation pose any health risk? 

Although these two options offer a wide variety of advantages to homeowners, they may also negatively affect the body. For instance, spray foam gas has its major ingredient as isocyanates, which when it comes in contact with the body can cause stomach, lungs, and eye irritation. 

Added to this, the chemical compound can cause severe skin inflammation and rashes when used without protective gear like gloves, an eye mask, goggles, or a respirator. In severe cases, exposure to this compound could lead to asthma attacks and long-term respiratory illness, which may end up in chemical bronchitis.

The good news is that this respiratory irritation can be cured. But to prevent this, you want to make sure to mix the spray foam components in the right proportions to prevent blurred vision and respiratory distress. 

On the other hand, fiberglass insulation is composed of glass wood fibers usually thought to be carcinogenic. If you're considering employing this method, you want to wear protective gear to prevent eye, skin, and respiratory irritation. This insulation method is also believed to be possibly cancerous when inhaled. 

Kenneth Wilson
August 22, 2021

Kenneth Wilson

Retired contractor. Currently residing in Southwest Florida. Now in semi-retirement, I write and manage this blog focused on helping home owners make savvy decisions when it comes to finding contractors and getting their projects done. I also operate remodeling design service for homeowners.

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