INSULATION

The R value of radiant barrier foil is zero.  But, because it reflects 97% of the heat entering your home, radiant barrier foil can improve the effectiveness of your current insulation.

Think of it this way, how much more comfortable would you be sitting in the shade on a hot sunny day versus sitting in the direct sun?  GTri-Foil creates a shade barrier similar to a tree hanging over your home.

Install Rhino Foil and you are covering your home in shade. Here's an example, fill two ice chests with cold drinks. Now place one ice chest in the shade and one in the sun.  Which ice chest will stay cold longer?

What about Bubble Foil?
Bubble foils have an R value but does it work as well as some think? That depends.

Here's another example that will explain...

Have you ever had a heavy jacket on during a cold winter day and unzipped it to stay warm?  Of course not!  If you leave it unzipped, it does not matter how thick the jacket, you're still cold. Now zip up the jacket and create a dead air space between you and the jacket and you stay very warm.

The same is true of bubble foil. Unless you can completely air-seal the bubble foil you will not get the full effectiveness of the R-value.

Should you use Bubble Insulated Foil?
Yes and no. It depends. In most cases, bubble foil is simply an extra expense with little or no benefit.

For example, would a 1 inch thick umbrella keep you any cooler on a hot sunny day?  Of course not because the air temperate is the same on both sides of the umbrella.

Would you install insulation on interior walls?  Of course not, it would be a complete waste of money. R value only matters if there is a difference in temperatures on both sides of the insulation.

The same is true if you staple bubble foil to the bottom of your rafters and allow air to flow on both sides.

Bubble foil does have its benefits.
It is recommended for metal buildings to stop condensation and on the backside of kneewalls to stop "hotwalls".

IMPORTANT: Stapling bubble foil to the bottom of your roof deck is overkill and more importantly, you could potentially trap moisture which could lead to mold.  Bubble foil does not allow water vapor to pass through.