When using core insulation the insulation should occupy all.
Insulation value of concrete walls.
For example if you have a type of insulation that has an r value of r 5 per inch of thickness you will need a depth of 6 inches of this insulation installed in your attic to reach r 30 if you live in zones 2 or 3.
Note from this.
By doubling the thickness of the wall to 16 inches the r value only increases by 0 50.
A wall s thermal resistance or its r value is its ability to slow the transfer of heat from one side to the other.
The products are easy to handle score cut and install and no special tools are needed.
However too many people confuse insulation properties with thermal mass many icf dealers d.
These r values are a sum meaning this should be the total r value once you add up the entire depth of insulation.
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.
Foam board to be placed on outside of wall usually new construction or inside of wall existing homes.
Therefore technically it has no insulation value.
Products can be used on wood steel framing or concrete walls.
New construction or major renovations.
And insulating concrete blocks.
As for the furring used for interior insulation the thermal resistance of the concrete masonry webs and any grouted cores should be accounted for when determining the thermal performance of the wall see tek 6 2c ref.
I agree mostly with junio s answer.
In simple terms r values measure the effectiveness of insulation and a higher number represents more effective insulation.
For instance if you have a material with an r value of 12 attached to another material with an r value of 3 then both materials combined have an r value of 15.
Unfinished walls including foundation walls.
Some manufacturers incorporate foam beads or air into the concrete mix to increase r values.
Products provide superior insulating properties.
But concrete is a conductor of thermal energy not an insulator.