Flash and foil insulation is a combination of a 1 to 2 inch layer of closed-cell foam and a radiant barrier. The idea is that you can use less of the expensive spray foam and fill in the balance of the R-value with a radiant barrier. Let’s take a look at how it performed on my house.

The results of the test are arranged into 3 segments:

1. Test setup - shows how the test bay was assembled.
2. Normal Winter - shows the test bay performance against the control bay on a moderately cold winter night with no wind.
3. Extreme Winter – shows the test bay performance against the control bay on a day that is either extremely cold or has a 20 mph wind. The process used to simulate an extreme winter day is to depressurize the space to 50 Pascals, a pressure 5 to 10 times normal pressure. Depressurization with a blower door is commonly used to locate air leaks in a structure.