When choosing insulation for your roof, both spray foam and radiant barrier have their pros and cons.

While a radiant barrier is less expensive and easier to install, it is not as effective at insulating as spray foam. On the other hand, spray foam is more expensive and difficult to install, but it is a much better insulator. So, which one should you choose?

The answer depends on a few factors, including your budget and the climate you live in. Here’s an overview of both insulation types and their use.

About Radiant Barrier

A radiant barrier is a reflective material typically installed on a home’s roof. The purpose of a radiant barrier is to reflect heat away from the house, which can help keep the house cooler in summer and warmer in winter. Radiant barriers are most effective in hot climates and can help reduce cooling costs by up to 10%.

Radiant barriers are made from several materials, including aluminum foil, metalized plastic film, and fiberglass. According to the Department of Energy (DOE), a product is called a radiant barrier if it has a reflectance of 90% or higher and an emittance of 10% or less.

Radiant barriers also exhibit a phenomenon called emissivity, which is the ability of a material to emit heat. Radiant barriers with a lower emissivity tend to be more effective at reflecting heat.

It’s important to note that radiant barriers do not have an R-value. That’s because R-value is a measure of how much a material slows conductive heat flow. Since radiant barriers reflect heat rather than absorb it, they don’t have an R-value.

Typically, there are two ways to install radiant barriers. The first is to staple the foil to the roof rafters’ bottom. In this way, the radiant barrier will reflect heat away from the house. The second way is to place the radiant barrier between the insulation and the drywall. It can be done either during construction or during a remodel.

Installing a radiant barrier is not a do-it-yourself project. Instead, a professional contractor should do it.

Cost: On average, it can cost $740 to $2,840 to install a radiant barrier. The cost of installation depends on the type of material. Most materials range from $0.10 to $0.95 per square foot. Since you have to get the installation done by a professional, the labor costs can be up to $80 an hour.


Here are the advantages of radiant barrier over spray foam insulation:

  • Not Affected by Humidity: Unlike spray foam insulation, a radiant barrier is not affected by humidity. That’s because it doesn’t absorb moisture.
  • No Irritants: Radiant barriers do not release harmful particles that irritate the skin, eyes, and throat. On the other hand, spray foam insulation installation requires several safety precautions to avoid irritation.
  • Pest Resistant: Radiant barriers are pest resistant. That’s because they don’t provide a food source or a nesting ground for pests.
  • Doesn’t Settle: Opposed to conventional insulation materials, such as spray foam, a radiant barrier does not settle or compress over time.


Here are some downsides of using radiant barriers:

  • Prone to Dust: Although not as bad as fiberglass insulation, radiant barriers can be dusty. It can reduce the reflectivity of the material.
  • Difficult to Install: Radiant barriers are difficult to install. On the other hand, you can install spray foam insulation yourself if you know how to work a spray gun.

Learn about 6 Undeniable Problems With Radiant Barriers And How to Avoid Them

About Spray Foam Insulation

Spray foam insulation is one of the most popular insulation materials on the market today. It is made from polyurethane and other chemicals that are sprayed onto a surface to create a foam. The foam can be used to insulate walls, ceilings, and other areas of a home or building.

Spray foam insulation works by creating a barrier between the inside and outside of a home or building. The barrier can also help to reduce noise levels and prevent roof leaks and moisture from entering a home or building.

Spray foam insulation is available in two types: open-cell and closed-cell. Open-cell spray foam is less dense and is often used for insulating walls, ceilings, and crawl spaces. Closed-cell spray foam is denser since the cells are encapsulated. It is commonly used in attics, basements, and other areas where there is a risk of moisture or water damage.

Spray foam tends to expand with the application. While open-cell foam can expand up to 3 inches, closed-cell foam only expands an inch. Therefore, the latter is better for tight spaces such as in attics and walls.

Both open and closed-cell insulation can be used in place of a radiant barrier. However, they should not be used together since spray foam will render the radiant barrier useless.

A radiant barrier needs an air gap to work properly. But since spray foam expands, it can fill the air gap and prevent the proper functioning of the radiant barrier.

Closed-cell spray foam has an R-value of up to 7 per inch. Meanwhile, open-cell spray foam’s R-value is around 3.8 per inch.

Since closed-cell spray foam is the better option for roofing applications, it can help reduce your energy bills. Plus, it strengthens the roofs by improving their structural integrity.

Cost: Closed-cell spray foam costs about $1 to $1.50 per board foot. Meanwhile, open-cell spray foam is cheaper at $0.44 to $0.65 per board foot.


Here are the advantages of spray foam over a radiant barrier.

  • Reduces Sound: Spray foam helps to reduce noise levels by providing a sound barrier. Thus, it’s ideal for use in homes or buildings near busy streets or airports.
  • Minimizes Allergens: Spray foam minimizes allergens, such as pollen, mildew, mold, and dust. A radiant barrier doesn’t have this advantage.
  • Enhances Air Quality: Since spray foam provides a seal between the inside and outside of a home, it can help improve air quality.


Spray foam lacks in the following regards:

  • Releases Irritants: Unlike radiant barriers, spray foam insulation releases irritants during installation. These chemicals can cause health problems, such as respiratory issues and skin irritation.
  • Expensive: Spray foam, especially closed-cell, is more expensive than other insulation materials, such as a radiant barrier.

So, When To Choose Radiant Barrier Over Spray Foam?

A radiant barrier is ideal if you live in a hotter climate since it will reflect heat away from your home, keeping it cooler. However, if you live in a cool climate, it’s best to work with thermal insulation, such as spray foam, since it will be more cost-effective.

Radiant barriers are also better if you need a budget-friendly solution since they are typically cheaper than spray foam. But spray foam is the way to go if you want the most energy-efficient option.

Moreover, you can use a radiant barrier on top of the roof decking. Many companies sell OSB radiant barriers that are easy to install during roof replacements and new constructions. Such a radiant barrier is made of metalized poly with one-sided lamination or aluminum. 

You have to install the foil side facing the attic space. Then, you can install shingles and felt on the top. Homeowners often use these radiant barriers with attic insulation to maximize energy efficiency. Here are some benefits of using radiant barrier on roof decking: 

  • Reduces heat transfer via the roof by 97% 
  • Lowers attic temperatures 
  • Lowers utility costs 
  • Extends the lifespan of a home’s AC and heating systems 

Do I Need A Radiant Barrier If I Already Have Spray Foam Insulation In Place?

No, if you already have spray foam insulation, you don’t need a radiant barrier. Rather, spray foam can negate the functionality of a radiant barrier if there’s no air gap between insulation and barrier.

Can You Use Both?

Radiant barriers need an air gap to be effective. So, if you use spray foam with a radiant barrier, the spray foam will fill the air gap, and the radiant barrier will no longer be effective. You can, however, a double-deck roofing system or add the foil via the cathedral ceiling method to combine spray foam and reflective barrier.


Justin's been in construction for over 20 years in both new build and renovation. With experience in both commercial and residential construction, he specializes in healthier and more energy-efficient homes.

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