This keeps the air from moving within the insulation and from penetrations between the air conditioned space and the attic.
Cellulose or fiberglass attic insulation.
In the summer according to research by the brookhaven national lab fiberglass loses 3 times more r value than cellulose when attics reach 110 degrees f very common in most areas of the country.
It has a better resistance to air flow and prevents the upward movement of air caused by temperature differences.
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.
Or 7 inches of cellulose.
The two main least expensive and most commonly used residential insulation materials is cellulose and fibreglass.
Loose fill fiberglass seems to dominate attic insulation in new construction homes and has an r value of approximately 2 5 per inch.
Cellulose insulation is considered green as it is made from recycled newspaper and requires less energy to manufacture than fiberglass insulation.
Cellulose has 38 better air infiltration than fiberglass.
Cellulose cellulose insulation offers many advantages to your home such as its r value of r 2 6 per 100mm metric which is better than glass wool or rock wool.
Cellulose insulation is considered a greener material than fiberglass.
Like cellulose you need a big machine to blow it in.
It does not pollute the air during manufacture or use as much energy to produce as fiberglass.
Cellulose is more difficult to cheat than fiberglass.
Cellulose insulation is also chemically treated to resist fire insects and mold.
Unless you opt for spray foam then the insulation choices normally come down to cellulose and fibreglass.
Fiberglass is a suspected carcinogen.
Attic blown cellulose is typically the preferred choice of insulation for attics.
Like cellulose you need a big machine to blow it in.
It is made from paper that has a minimum of 85 recycled content such as newspaper.
Sources many fiberglass installers fluff the fiber with extra air so you don t get as much insulation as you re supposed to.
Cellulose forms a dense continuous mat of insulation in your attic.
You can get to the same place with either material.
Rather than trying to meticulously lay fiberglass insulation over the attic homeowners and builders can simply blow cellulose insulation throughout the attic.