Radiant Barrier vs Spray Foam Insulation (Pros & Cons)

When it comes to keeping your home cool in the summer or warm in the winter, you want to know which type of insulation will save you the most money, offer the least headache during installation, and give the best long-term ROI. 

In this post, we’ll give an in-depth look at the pros and cons of radiant barrier sheathing insulation versus spray-in foam insulation. Which one is the clear winner?

Table of Contents

• Radiant Barrier Sheathing Explained
• Best Use Cases
• Types of Radiant Barrier
• Radiant Barrier Pros
• Radiant Barrier Cons
• Spray Foam Insulation Explained
• Best Use Cases
• Types of Spray Foam
• Spray Foam Pros
• Spray Foam Cons
• Cost Comparison
• R-Value Comparison
• Factors to Consider
• Case Studies
• Final Winner

First, you need to understand how heat is transferred. 

Basics of Heat Transfer 

There are three types of heat transference: 

• Conduction is when heat moves through objects touching one another. Some materials offer better heating conductivity than others.
• Radiation is when heat flows through the air, a vacuum, or glass from a single source, like a portable heater or the sun.
• Convection is when heat transfers through a moving gas or fluid. Think of a boiling pot of water. 

Spray Foam vs. Barrier Sheath: Insulation Performance 

Spray in foam: protects against conduction and convection heat. 

Radiant barrier: exclusively protects against radiant heat. 

Combine Insulation Types? 

You might be wondering “Why not combine the two forms of insulation and get the best of both worlds? It’s because it will negate the effectiveness of radiant barrier sheathing. 

Cellulose insulation will block the radiant barrier from absorbing any heat or radiating it out. 

INSULATION COMPARISON CHART 

Radiant Barrier Sheathing Insulation Material Explained

Light, durable, and inexpensive—radiant barrier insulation works effectively to reflect heat off its surface, despite having little to no “insulation” properties (no R-Value).  

It’s even used by NASA to reflect thermal radiation and keep temperatures inside of a ship regulated. 

The material has a metallic sheen that is similar to what you’d see on aluminum foil. 

It can reflect up to 97% of heat radiation. According to the U.S. Department of Energy, after installing radiant barriers in your attic, temperatures can decrease heat gain by 40%, usually around 30 degrees, which can mean a 17% reduction in your heating bill. 

Best Use Cases 

Typically, radiant barrier sheathing has a limited scope of application. It’s mainly used in attics or crawl spaces. 

• Attics (the best place for spray foam insulation) 
• Garage doors
• Hot water heaters
• Roofs, floors & walls
• Crawl spaces 

However, the material can be used on the walls outside of a home to reflect heat, or on the gables, which are the triangle-shaped portions of a wall between the edges of intersecting roofs. 

Types of Radiant Barrier Sheathing

Two styles of radiant barrier sheathing: 

• Perforated or “Breathable” (small holes within the insulation)
• Non-perforated (tear- and tear-resistant material) 

If you want to insulate your attic, you absolutely need to use a perforated radiant barrier since this will protect your space from moisture-heavy air. If you need more airflow, breathable perforated radiant barrier insulation is the preferred option. 

On the other hand, a solid vapor barrier (no holes) is preferred in northern climates or coastal areas with a lot of moisture and water exposure. 

The most common types of radiant barriers include: 

• Single-sided foil (one-sided foil). It’s a stronger material with a fiber webbing between the foil and the backing. 
• Foil-faced roof sheathing materials. This has the foil affixed to one side of the sheathing. 
• Double-sided foil. The reinforced backing might be made of cardboard, drafting paper, or fiber webbing. 
• Multi-layered foil. These deter the condensation challenges that occur with bubble-foil or single-foil insulation barriers. 

Radiant Barrier Pros 

• Cheaper 
• Easy installation 
• Lightweight 
• No settling
• Perfect for humid or hot climates

Radiant Barrier Cons 

• Not as effective in colder climates 
• No insulation value (R-Value) 
• Accumulates dust (which lowers heat reflectivity)  

Spray Foam Insulation Material Explained

Spray in cellulose foam insulation is sprayed in as a liquid substance that congeals to a surface, creating an airtight seal that prevents the transmission of heat in and out of a space. 

When there are roof trusses, things get more complex. It becomes difficult to identify leaks in your roof after you’ve applied spray foam. This is because it is glued directly to the area and can end up soaking moisture from the roof decking. 

Best Use Cases

Spray-in foam insulation is used in most places around a home:

• Attic 
• Walls 
• Basement 
• Crawlspace

It’s the perfect choice for filling in floor crevices, gaps, joists, and corners. The tight, compact seal creates higher insulating properties, eliminating cold drafts, reducing air leaks, and creating a temperature-regulating atmosphere. 

(For a detailed R-Value chart, read “Insulation R-Values Chart and Buyer Guide.”

This chart shows the approximate R-value per inch of various insulating materials.

Types of Spray Foam Insulation 

Open Cell Spray Foam 

• Softer, more flexible material 
• Lower R-Value (3.5 per inch) 
• Better for hard-to-reach areas, nooks and crannies 

Closed Cell Spray Foam 

• Rigid, dense, and inflexible for a more air-tight seal
• Higher R-Value (6.0 per inch) 
• Better for walls and attics to maintain structural integrity

Spray Foam Comes in 3 Categories

1. High density: 3 lbs./cubic ft.
   R-Value starts at 5.5 per inch and poses greater resistance to the elements, which is why it’s used on exterior parts of the home, like roofs. 
   
   
2. Medium density: 2 lbs./cubic ft. 
   R-Value starts at 5.7 per inch and offers moderate resistance to elements. It’s best used for interior walls and attic spaces. 
   
   
3. Low density: 0.5 lbs./cubic ft. 
   Offering the lowest R-Value, 3.6 per inch, it’s not as rigid or resistant to the elements; therefore, its best use is for interior wall cavities, nooks, crannies, and jolts in an attic. 

Spray Foam Pros 

• High R-value 
• Versatile (walls, floors, attics) 
• Moisture barrier 
• Noise reduction 

Spray Foam Cons 

• Requires professional installation 
• More expensive 
• Toxic chemicals from spray 
• Lack of ventilation due to being densely packed

Cost Comparison Guide 

Radiant Barrier: $740 to $2,840

Prices can range from $0.15 to $0.75 per square foot, depending on the brand you choose and the method of installation. 

Spray Foam: $1,284 to $3,741

Price ranges depend on the thickness and density of the foam. It can cost anywhere from $1.50 to $3.50 per square foot. 

Factors To Consider Before Buying Insulation 

• Climate
  
  Hot, humid, and moist climates are best for spray-in foam insulation. It’s so versatile it can honestly be used in nearly any climate, hot or cold. 
  
  Hot, sunny, and dry climates are more appropriate places for radiant barrier sheathing, which doesn’t offer the same protection against moisture. 

• Budget & Cost
  
  Spray-in foam is more expensive on its face. But before you brush it off, consider the long-term cost savings from better energy efficiency. With that in mind, spray-in foam wins out over radiant barrier insulation. 
  
  If you want immediate cost savings or you’re on a budget, get radiant barrier sheathing. 
  

• Sustainability
  
  Spray foam is more environmentally friendly than alternatives like cellulose or fiberglass insulation. However, it can leave some toxic particulate matter behind after application. It’s not a long-term concern. These particulates dissipate over time. 
  
  Radiant barrier sheathing materials are often recyclable and eco-friendly. However, it is not biodegradable. Different manufacturers offer options for recycling their products. 
  

• Application  
  
  Spray-in foam insulation is both expensive and difficult to install, and for those thinking about doing it alone, it’s quite dangerous without the right equipment. 
  
  To do it correctly, you’ll need to hire a specialist to come to your home and apply the spray foam while wearing personal protective gear. 
  
  Radiant barrier insulation is simpler to install. You can easily tack it onto the rafters or lay it on the floor of your attic. Open-celled spray-in foam insulation requires special equipment, personal protective gear, and trained installers. 
  
  A radiant barrier attached to the rafters is a better option than laying it on the attic floor and even better still than laying down a painted radiant barrier. 
  
  A third option to consider is using raised heel trusses. That way, you’ll have more space for insulation. You can then use more blown-in cellulose or fiberglass batts alongside radiant barrier sheathing to improve the R-value of your attic. 
  

Case Studies

Here’s a case study of an award-winning home that incorporates GPS foam in its structural insulated panels (SIPs) and  Icynene spray foam in the floor. The result is a home that is net-zero energy and offers healthy indoor air quality. 

In this case study, learn how to use radiant barriers to insulate an attic. 

How to Decide? Review Your Local Building Codes

If you’re unsure what insulation type to use for your property, consult with a professional to see what building codes are required. Your best bet is to contact your municipalities building department. They can provide you with the latest code information for your area. 

Spray Foam vs. Barrier Sheathing: Which is the Winner? 

Both radiant barrier sheathing and spray-in cellulose foam insulation offer advantages and disadvantages. Before you buy, remember to review factors like your budget and building code requirements. 

All in all, if you’re willing to invest in it, spray-in foam offers the better choice for insulation. It’s more versatile and offers a higher R-Value, leading to better energy efficiency and can generate a solid long-term return on investment.