The two main least expensive and most commonly used residential insulation materials is cellulose and fibreglass.
Fiberglass insulation vs cellulose insulation for attic.
You can get to the same place with either material.
Dirty fiberglass batts have a significantly reduced r value.
Rather than trying to meticulously lay fiberglass insulation over the attic homeowners and builders can simply blow cellulose insulation throughout the attic.
This is called wind washing.
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.
Cellulose provides better sound insulation than fiberglass i e homes are less noisy with it.
Or 7 inches of cellulose.
Thus creating a more energy efficient home.
Unless you opt for spray foam then the insulation choices normally come down to cellulose and fibreglass.
It has a better resistance to air flow and prevents the upward movement of air caused by temperature differences.
Many fiberglass installers fluff the fiber with extra air so you don t get as much insulation as you re supposed to.
Fiberglass is a suspected carcinogen.
Air moving through a vented attic deposits dirt and dust into fiberglass batts.
Cellulose insulation is also chemically treated to resist fire insects and mold.