Enter Existing R-value, and the R-value you require,
check chart for options.
Use a combination of options as required.
Go to closest even number.
To determine existing R-value, enter .01 into Existing R-value,
match your type of insulation to that on the list. Juggle the
Required R-value until the level on the list is the same as you have,
that is your existing R-Value.
Feel free to click the +1 button if you found this helpful.