Attic Insulation Cellulose On Top Of Fiberglass

The vapor retarder on top of or between layers of insulation can trap moisture.

Attic insulation cellulose on top of fiberglass.

Fiberglass is just that thin fibers of glass that trap air. It will however fill in all the gaps that fiberglass batts leave along side of your ceiling joists if you see wood its no good and add the to your r factor cellulose is second best with spray 2 part high density spray foam as first in my book. Unless you opt for spray foam then the insulation choices normally come down to cellulose and fibreglass. Insulation should be rolled out perpendicular to the joists and unfaced rolls should be used.

Cellulose blown in ceiling insulation is a good choice for diyers. But if you have clumpy fiberglass insulation in your attic now you may want to check it with a moisture meter before adding anything on top of it. Loose fill fiberglass attic insulation still experiences convection but not nearly as much as old fiberglass used to. It can be used by itself to fill in joist cavities that have no insulation or laid as a thick layer over the top of existing batts of fiberglass insulation.

Most attics are insulated with blown in loose cellulose r 3 5 per inch blown in loose fiberglass r 2 5 per inch or fiberglass batts r 3 2 per inch. To hit code minimums you ve got to add new insulation on top of the old insulation. You can get to the same place with either material. Any existing batt or roll insulation in the attic should have the facing against the attic drywall floor or no facing at all.

Also cellulose is a dusty product whereas fiberglass blows in pretty clean. I would add more fiberglass insulation to the top of what you already have as it will not compress as much as cellulose does. The installation process for dry cellulose insulation looks like this. Blown in cellulose is an environmentally friendly material made from recycled newspaper so it s easier on your skin and lungs.

Originally posted by benjamin thompson part of the advantage of cellulose is the tight air barrier. 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.

Blown in cellulose has a higher r rating and is less expensive than either blown insulation like fiberglass attic insulation or fiberglass batts. Cellulose is recycled newsprint treated with a fire retardant. When there are fiberglass batts in your attic the cellulose will not draft block the top plates. If you check with the north american insulation manufacturers association they ll assure you that fiberglass or mineral wool is definitely your best choice for attic insulation.

One of the benefits of placing cellulose insulation over fiberglass insulation is the cellulose if installed properly will provide an air barrier something fiberglass insulation cannot do.