Unless you opt for spray foam then the insulation choices normally come down to cellulose and fibreglass.
Fiberglass insulation vs cellulose insulation for attic.
Air moving through a vented attic deposits dirt and dust into fiberglass batts.
You can get to the same place with either material.
The two main least expensive and most commonly used residential insulation materials is cellulose and fibreglass.
Because it is denser than fiberglass cellulose is much more resistant to wind washing.
Thus creating a more energy efficient home.
This allows the insulation to get into the small pockets and crevices that fiberglass wouldn t be able to.
Cellulose insulation is considered green as it is made from recycled newspaper and requires less energy to manufacture than fiberglass insulation.
This is called wind washing.
Or 7 inches of cellulose.
Rather than trying to meticulously lay fiberglass insulation over the attic homeowners and builders can simply blow cellulose insulation throughout the attic.
Cellulose insulation is also chemically treated to resist fire insects and mold.
Assuming your current attic insulation is made from fiberglass and has a value of r 13 you d have to add roughly 10 inches of additional fiberglass to hit r 38.
Fiberglass is a suspected carcinogen.
It has a better resistance to air flow and prevents the upward movement of air caused by temperature differences.