If the insulation is a foam board or sprayed on foam use any visible label information or multiply the thickness in inches by 5 to estimate the r value.
Desired r value for attic.
Where you live different climates require different insulation r values.
The recommended r value for attic floor insulation for this house is r 38.
There are many ways to retrofit a home with fiberglass and.
Look at your ductwork.
For houses in a southwestern state or other areas with generally warmer temperatures you might need attic insulation with an r value of only r 30.
If the existing attic floor insulation has an r 11 insulation value then an additional r 27 would be needed to bring the attic floor insulation up to the level recommended for that house.
Existing 3 4 inches of insulation.
It will most likely be a fiberglass batt so multiply the thickness in inches by 3 2 to find out the r value or the r value might be visible on a product label.
Add insulation to attic.
Your home s age if your home is more than 10 year old you likely need more insulation.
Recommended insulation levels for retrofitting existing wood framed buildings.
You will need a higher r value of insulation if you live in the northeast than if you live in southern california.
The homeowner could then check table 1 to find several choices.