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Spray Foam Insulation vs. Fiberglass: Efficiency Compared

Determine which solution is best for your home: spray foam insulation vs. fiberglass. Insulation options vary in effectiveness, particularly in locations with severe temperature fluctuations. Spray foam and fiberglass remain common choices, but their prices differ considerably. To make the right decision, compare their efficacy, sustainability, cost, and overall value before seeking expert help for professional insulation installation.

Is Foam Insulation Better Than Fiberglass? 

Generally, yes, spray foam offers superior insulation compared to fiberglass.

Here's why: spray foam offers a higher R-value. Simply put, the higher the R-value, the better the insulation. Spray foam boasts a significantly higher R-value per inch compared to fiberglass. This translates to better thermal resistance, potentially leading to a more comfortable home and lower utility bills.

However, we'll delve deeper into the specifics of both materials in the following sections. We'll discuss their pros, cons, and ideal applications. For instance - fiberglass insulation is cost-effective and has a simpler installation procedure. But foam insulation stands out for its high R-value and its air-sealing ability.

The best option for your home will be determined by your needs and budget. So, continue reading our blog to learn more.

Spray Foam Insulation

Spray foam insulation has two types: open-cell and closed-cell. Closed-cell spray foam acts as an air, moisture, and vapor barrier, and open-cell primarily serves as an air barrier.

Professional contractors create spray foam insulation by mixing isocyanate and polyol resin in the spray gun's tip. Storing these chemicals separately and combining them forms a foam solution that dries in place, creating an effective air seal and moisture barrier.

The foam's tiny air gaps, or cells, prevent heat flow and sound waves from easily passing through. Its expansive nature allows it to fill even the smallest cracks and fissures, making spray foam the best overall insulator.


High R-Value

R-value is industry lingo for thermal resistance per unit area. R-value measures how well insulation resists heat flow in and out of your home. You want an insulator with as high of an R-value as possible.

Below is the R-value of spray foam (closed-cell and open-cell) vs. fiberglass:

  • Closed-cell delivers a thermal resistance value of 7 per inch.
  • Open-cell offers an R-value of 3.5 per inch
  • Fiberglass batts have a non-aged R-value of 2.2 per inch.

Furthermore, spray foam insulation maintains its R-value over time. Fiberglass insulation, on the other hand, loses its R-value as time passes and often requires replacement within ten years.

With proper installation, spray foam remains the stronger, more effective, and better cost-saving option.

Water Resistance

Spray foam insulation generally provides two key benefits for homeowners. This protective barrier guards against moisture in the attic or crawl space and remains water-resistant during floods. Professional installation reduces the chances of long-term damage, preserving the building's integrity and appearance.


Spray foam insulation's rapid expansion seals gaps and fractures in walls, attics, and crawl spaces, reducing energy loss and lowering utility bills. Spray foam keeps the house comfortable all year long. It eliminates energy-wasting drafts by reducing air permeability by 24 times the average.


Because it is composed of polyurethane and isocyanate, spray foam insulation provides long-lasting insulation. As a wall reinforcement, it offers some defense against winds, snowfall, and earthquakes. Also, spray foam insulation maintains its effectiveness over time without sagging or requiring replacement.

With a high R-value, it has the most heat-resistant, energy-saving properties, making it a sensible, economical choice. Its versatility allows it to fit any space. It acts as a strong adhesive, protects roofs from ice dams, and increases property value.

Improved Health

Applying spray foam insulation is an excellent choice for eco-conscious households. It maintains R-value in adverse weather, blocks out air pollutants, and lacks a cancer warning label, ensuring the safety of all occupants.

Spray foam insulation absorbs sound and improves comfort in all weather. This insulation material reduces resource consumption, prevents moisture damage, and enhances the home's energy efficiency, promoting sustainability and protecting homeowners' respiratory health.



When comparing fiberglass insulation vs. spray foam, both open and closed-cell foam insulation cost more up-front. However, these insulation materials are cost-effective, energy-efficient, and offer superior performance. Although spray foam insulation costs more, it justifies its higher price with long-term savings on heating and cooling bills.


Amateur Installers often overlook the depth requirements for spray foam and fiberglass insulation, leading to inadequate support and reduced energy efficiency. Failure to properly install open and closed-cell spray foam may lead to air gaps, ice dams, and mildew growth.

Fiberglass Insulation

Fiberglass insulation effectively insulates homes, creating a barrier that blocks airflow and traps heat. Adding insulation keeps a house cooler in the summer and warmer in the winter, making them more comfortable and energy-efficient. It comes in two main types: loose-fill and blankets, also known as batts.



Fiberglass batts remain popular for budget-conscious homeowners because of their cost-effectiveness and ease of installation. Prices range from $0.30 to $1.50 per square foot, meaning fiberglass insulation costs less than spray foam insulation.


Fiberglass is the most economical insulation due to quick installations and lower labor costs. Insulating a 500-square-foot area may cost between $150 and $750, allowing homeowners to save money with its lower product and labor costs.

Fire Resistance

Made from sand and recycled glass, fire-resistant fiberglass promotes safety. This naturally fire-resistant material performs better when treated with a fire retardant. When exposed to direct flames fiberglass melts instead of burns, providing non-combustible insulation and protection to structures without creating a fire risk.

Noise Reduction

Fiberglass insulation has natural sound-dampening qualities, making it ideal for acoustic insulation in ducts, walls, and ceilings. Fiberglass insulation reduces outside noise, creating a peaceful living environment.

Environmentally Friendly

Made from recyclable materials with over 30% recycled components, fiberglass insulation is an eco-friendly option. It promotes indoor air quality by inhibiting mold and mildew, creating a healthier living environment. It enhances a home's energy efficiency by creating air pockets that prevent heat and cold transfer, reducing heating and cooling costs.



Fiberglass insulation's R-value decreases over time, affecting its thermal resistance. Consider switching to a material with a higher R-value for increased comfort and energy efficiency. It will offset the replacement cost with long-term energy savings.

Moisture Sensitivity

Fiberglass insulation is prone to wetness and mold issues. To address this, use a vapor barrier to protect the insulation. Promptly addressing mold formation and scheduling regular insulation checkups remains vital for a healthy home environment.


Fiberglass insulation may resist heat flow, leading to discomfort due to significant temperature fluctuations. To combat this issue, some contractors create an air seal by applying a thin layer of foam spray to walls and attics before installing fiberglass insulation. This method enhances the effectiveness of fiberglass insulation, lowers energy bills, and ensures a more comfortable living space.

Choosing the Right Insulation for Your Home

When selecting insulation, homeowners should consider several factors, including cost, energy efficiency, longevity, and indoor air quality. Spray foam insulation offers superior energy efficiency and air-sealing capabilities, leading to long-term savings on energy bills.

Cost Comparison

The price difference varies with the insulation material's properties, installation method, and effectiveness. Spray foam insulation installation costs around $3 per square foot for 3 inches of thickness. Fiberglass insulation costs approximately $0.40 per square foot.

Other cost considerations:

• Open-cell spray foam: $0.44 to $0.65 per board foot
• Closed-cell spray foam: $1 to $1.50 per board foot
• Fiberglass batt insulation: $0.30 to $1.50 per square foot

Different areas of the house may have varying costs for insulation:

• Basement: $1.50 to $2.50 per square foot
• Attic: $1,500 to $6,000 total
• Roof: $1,500 to $4,500 total
• Wall: $1 to $4 per square foot

Environmental Impact

Fiberglass insulation remains a green solution. Manufacturers use recycled glass and sand, so fiberglass insulation does not release harmful toxins into the air. However, glass wool insulation with fibers is considered carcinogenic and might irritate the respiratory system.

Spray foam insulation has environmental benefits. It uses less energy, emits few greenhouse gasses, and reduces landfill waste. However, it contains harmful hydrofluorocarbon-based compounds and blowing agents.

Both insulation types have energy efficiency benefits, but homeowners should consider their environmental impact and potential health effects. Following safety precautions during installation remains crucial, and the decision between the two will depend on individual preferences and needs. Ultimately, spray foam has superior heat loss prevention and acts as an air seal, making it the better choice.

Energy Efficiency

Spray foam offers a high R-value, year-round comfort, and air quality improvement — an energy-efficient solution. It resolves draft issues, lowers utility costs, and does not settle.

Fiberglass reduces noise and cuts heating and cooling costs by 40%-50%. Fiberglass proves more affordable, but less effective in reducing air leakages and has less heat resistance.

When choosing between the two, finances play a crucial role. Spray foam has a higher upfront cost but leads to long-term energy savings. It eliminates the need for vents, reduces the required HVAC size and price, and cuts heating and cooling needs by up to 50%.

Open or closed-cell options make a wise investment. Homeowners can recoup the initial cost within 3-5 years in cold climates. Even the savings of 10%-15% in new homes makes it a compelling choice.


What are the disadvantages of spray foam insulation?

The disadvantages of spray foam insulation are the cost and installation. However, an insulation contractor will help minimize costs and speed up installation. With their expertise and experience, a professional team will ensure they install spray foam according to building codes. Hiring an expert protects your investment and helps you avoid costly repairs in the future.

When should you not use spray foam insulation?

You should not use spray foam insulation for homes with moisture issues, as it can retain more moisture and promote additional mold growth. Adding spray foam insulation does not affect the energy efficiency of modern, well-insulated homes very much.

How long does spray foam insulation last?

Spray foam insulation lasts 80 to 100 years with a proper installation, offering long-lasting durability and efficiency. It requires no maintenance and does not deteriorate, sag, or settle like cellulose insulation and fiberglass, ensuring its strength throughout the building's lifetime.

Improve Your Home's Insulation with iFoam

Now that you know the different types of insulation, you can decide which insulation is right for you. Enhance your home's insulation with a professional installation from the best insulation contractors. Call iFOAM at (855) 935-4723 to schedule a free consultation today!