What is Radiant Barrier and Why It Works?

Looking for ways to have efficient energy for your attic? Radiant barrier technology is your best bet. However, in order to apply this, you will have to understand what radiant barrier is and why it works.  

What is Radiant Barrier?

A radiant barrier is a barrier that blocks UV heat which could penetrate and heat objects and spaces inside your attic. In other words, it is a radiant barrier that reflects heat back to its source and keeps objects from being energized by UV rays. 

So What is Radiant Heat?

Radiant heat is energy that is transferred without any contact. Something could heat up and that heat will emit in all directions.

Quick Explanation- Where do you park your car?

To simply explain radiant barriers better, consider the best place to park your car. When you park in an open space and temperature hits 100 degrees, what do you think will happen? Yes, the inside of your car will feel like it’s an oven and the temperature inside your car would be much higher than the temperature outside. Why do you think that is? The reason behind this is as the sun hits your car’s windshield and heats it up, it hits your dash and that will heat as well. It keeps the heat and energy is stored on the material which makes it generate the heat back into the vehicle’s interior. 

If you have parked your car under the shade of a tree on the same temperature of 100 degrees, what do you think the temperature of your car’s interior will be?  Yes, it will be close to 100 degrees. 

The tree does not do anything to cool your car as it only blocks the radiant heat which would still cause for your vehicle to emit its own heat which will cause the temperature to rise. 

Radiant barriers function much like an umbrella. It puts you in shade so that the sun would not hit your directly. It will feel not hotter than ambient temperature – temperature of actual air. 

Science and Charity Stuff

Radiant heat from sun hits attic roof which heats it up. It heats up the shingles, plywood decking and trusses. It then radiates their own heat in all directions. Half of the heat goes back out but the other half continues to go into the attic space. It insulates the attic, the floor, the drywall, your ceiling and your living space. This also includes your AC ductwork which makes it very counterproductive. 

What is Radiant Barrier Technology?

If you add a radiant barrier technology with proper ventilation, not all of the heat will bounce back but rather a huge portion of it does. Hence, instead of your attic going up to 160 degrees Fahrenheit it will stay at around 100 to 110 degree. It is much cooler. However, with the use of a radiant barrier, this will block the radiant heat coming from the sun and will block conductive heat flow. This technology ensures that your attic insulation would work better. There are even some that would help you save energy as well. 

What about Insulation or more insulation?

Here are our recommended insulation R-values for wood-framed building per energy star:

R zone Values USA

Zone 1

  • Uninsulated attic: R30 to R49
  • Existing 3–4 inches of insulation: R25 to R30
  • Floor: R13

Zone 2

  • Uninsulated attic: R30 to R60
  • Existing 3–4 inches of insulation: R25 to R38
  • Floor: R13 to R19

Zone 3

  • Uninsulated attic: R30 to R60
  • Existing 3–4 inches of insulation: R25 to R38
  • Floor: R19 to R25

Zone 4

  • Uninsulated attic: R38 to R60
  • Existing 3–4 inches of insulation: R38
  • Floor: R25 to R30

Zone 5 to 8

  • Uninsulated attic: R49 to R60
  • Existing 3–4 inches of insulation: R38 to R49
  • Floor: R25 to R30

Insulation is not enough

Unfortunately, insulation is not enough. It does not defend you from the rising radiant heat levels that your attic could experience. It will heat it up as there isn’t something that could block the transfer of heat. Also, insulation is made better by a radiant barrier. In other words, as the insulation in your attic stays cooler, your living space would stay cooler.


We hope that through this article, we are able to convince you the importance of installing and using a radiant barrier and enjoy having a cool attic even in warmer climates. Here are some radiant barrier products which we highly recommend that you check out:

  • AtticFoil (available in 26”, 48” and 60” width rolls)
  • REACHbarrier.com –this comes with specific products for attics, water heaters, garage doors and many more. 


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