There are many ways to retrofit a home with fiberglass and.
Desired r value for attic.
Existing 3 4 inches of insulation.
Your home s age if your home is more than 10 year old you likely need more insulation.
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.
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.
The recommended r value for attic floor insulation for this house is r 38.
Look at your ductwork.
The homeowner could then check table 1 to find several choices.
Add insulation to attic.
Where you live different climates require different insulation r values.
R value insulation chart find your zone on the map and then use the chart to determine the level of insulation you need to properly insulate your attic walls floors and crawlspaces.
Recommended insulation levels for retrofitting existing wood framed buildings.
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.
You will need a higher r value of insulation if you live in the northeast than if you live in southern california.