You can install more insulation than that if you want to.
R value for concrete basement walls.
In one step epitome foundation composite walls incorporate r16 5 insulation vapor barrier top plate and stud framing within a 9 high durable basement wall structure.
In climate 4c the 2012 irc requires a minimum of r 15 for basement walls assuming that we are talking about continuous rigid foam or spray foam insulation the best approach.
0 13 0 64 30.
Typical residential weight concrete 8 wall r 2 5.
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.
The table below shows what levels of insulation are cost effective for different climates and locations in the home.
By doubling the thickness of the wall to 16 inches the r value only increases by 0 50.
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.
Concrete block makes a cost effective and structurally sound wall but it has little thermal resistance.
Generally zones 1 and 2 cover the southern states which suggest no necessary values to r 10 for basement walls.
Concrete or concrete block walls have the same r value as a 1 9cm thick particle board.
The higher the r value the better the thermal performance of the insulation.
Zones 3 and 4 include the midwest and northern regions requiring r 10 to r 19 values.
8 thick concrete slab or foundation wall has an r value of about 1 04 30 while lightweight aggregate filled 8 thick concrete has an r value of about 2 18 30.
Extremely northern regions and high elevations are zone 5 requiring r 15 to r 19 values.
Concrete sand gravel aggregate.
That s a minimum r value.
It s up to you to decide the r value of your insulation.