What are R-Values ?

R-Value: a measure of the resistance of a substance (in our case insulation) to heat flow.

This is what the dictionary says about R-value. But does that mean that everything we see printed is giving us a clear picture of that product? No! This is where things get confusing. Labels printed on bags, or other literature do not necessarily reflect the performance in the field, or rather, in your home, office, or warehouse. Why is that?
Before I explain that, here are a few more terms to understand.

Advertised R-value: This is the stated manufacturers R-value as it was tested. Usually by itself, under laboratory conditions.

Whole R- value: This is the resistance value of a whole wall system, ie: what R-value does the wall in your home, office or warehouse, operate at. This is the true test of what your product offers.

This is why a 2x6 wall that is advertised at an R 19 only operates at a R-13.69, or a 2x4 wall advertised at R-13 only operates at an R-9.58.

So when you are choosing methods to insulate, please take time to examine all the facts. The product you choose should not only be high in R-value, but it needs to act in your wall as it is advertised.

Want to read more?
Click here for David B. South's informative article entitled "R" Fairy Tale