Brian doe s wall foam r value question brian.
R value concrete wall basement.
By doubling the thickness of the wall to 16 inches the r value only increases by 0 50.
The department of energy provides a service to determine the exact r value required based on zip code and type of heating fuel.
The chart you cite is for the above ground framing.
These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.
The cool concrete of the foundation wall will collect humid air which will condense on its surface.
Consider adding insulation to the outside of the basement wall this can serve as protection for your waterproofing also.
You are confusing the minimum thickness of foam on the outside of above ground framing with the code required r value for basement wall insulation using foam.
Generally zones 1 and 2 cover the southern states which suggest no necessary values to r 10 for basement walls.
The r value of an uninsulated 8 inch thick basement wall built using normal weight concrete is 1 35 based on data from the 1993 american society of heating refrigeration and air conditioning engineers handbook.
The code cited by martin is for basement walls.
Zones 3 and 4 include the midwest and northern regions requiring r 10 to r 19 values.
Foam insulation is preferred over fiberglass as it has a higher r value is resistant to moisture.