Can you put cellulose over fiberglass insulation?

Can you put cellulose over fiberglass insulation?

Adding new cellulose insulation on top of existing fiberglass insulation is called “capping”. If you have some insulation in your sidewalls, cellulose can usually still be forced in with the dense-pack method to achieve the desired R-factor.

Can you dense pack fiberglass insulation?

Near as I can tell, modern day dense pack fiberglass at 1.8+ pounds per sq ft. insulates and slows air/vapor flow nearly as good as dense pack cellulose at 3 or 3.5 pounds per sq ft.

Does dense pack cellulose need a vapor barrier?

Dense pack cellulose and dense pack fiberglass are not air barrier materials, and they do not result in air barrier assemblies.

Does dense pack cellulose settle?

Called dense packing, the cellulose is slightly compressed during the installation process, allowing more fibers to fit in the same space. As the extra air in the cellulose is released, the compressed fibers expand to fill the void, reducing or eliminating settling.

Can you put blown-in insulation over fiberglass insulation?

A: There’s no problem with installing fiberglass batts over your existing blown-in insulation. The only thing you want to make sure of is that you use “unfaced” insulation, meaning it doesn’t have a paper or aluminum foil facing on the batts.

What is R-value of dense pack cellulose?

between 3.8 and 4.0 per inch
Loose-fill cellulose insulation offers an R-value of around 3.5 per inch of thickness, while densely packed cellulose boasts an R-value between 3.8 and 4.0 per inch. This value is higher than other insulating materials within a comparable price range.

Does cellulose insulation air seal?

To air seal and insulate the confusing spaces at the top of interior walls, we’ve found that house wrap and dense-pack cellulose are particularly useful. We hang house wrap over the short attic walls and other large areas of strange and leaking framing.

Does cellulose insulation block air?

Cellulose is a superb air-blocker. Heat and comfort are also lost through convection; when drafty currents of air within the house, wall cavities or attics, move heat to other locations.

Does cellulose insulation settle more than fiberglass?

Settles After Installation – Cellulose insulation tends to settle by several inches after it’s installed, which causes it to decrease in effectiveness. Mold Grows When Wet – Like fiberglass, cellulose is ineffective when wet, but unlike fiberglass, it can also be dangerous.