Question - Can you put cellulose on top of fiberglass insulation?

Answered by: Bonnie Garcia  |  Category: General  |  Last Updated: 07-09-2021  |  Views: 1289  |  Total Questions: 13

Any type of attic insulation can be installed over any other type: fiberglass over cellulose, cellulose over fiberglass -- it makes no difference. The fiberglass must be unfaced, however, or encased in perforated poly bags. Otherwise, condensation could develop on the facing. Cellulose Vs Fiberglass which blown in insulation material is best: If you compare both the material type with regards to their R-value per inch then fiberglass has approx. Cellulose properly insulates the attic because it forms a dense continuous mat and keeps the air moving within the insulation. You can mix and match the various kinds of insulation. For example, if you have cellulose insulation, and more insulation is needed, you can add any type you wish. It is also acceptable to use batts over loose-fill material and loose-fill material over batts. Cost: First off, both cellulose and fiberglass are inexpensive. Among the wide range of available insulation materials — including XPS foam board, EPS, polyisocyanurate, rock wool, and spray foam — cellulose and fiberglass are, inch for inch and square foot for square foot, the least expensive.

Loose-Fill Insulation Cellulose is the most effective material and has an R-value of 2. 2 to 3. 8 per inch, but if exposed to moisture it can get moldy.

Cellulose insulation is safe. It is made of paper, but the chemical treatment provides it with permanent fire resistance. There's been static generated by the fiberglass industry warning that cellulose could burn. But independent testing confirms it's safe and cellulose is approved by all building codes.

The insulation settles: As a loose-fill product, cellulose relies on its natural fluffiness to fill the space while leaving insulating air pockets between the fibers. Mold growth sets in: Thanks to its chemical treatment, mold doesn't grow on cellulose insulation.

The best insulation options for an attic are open cell spray foam, fiberglass, and cellulose. Cellulose is the oldest insulation material used for not only the attic, but other areas of the home as well. Fiberglass is another traditional insulation material that consists of extremely fine glass fibers.

Before you blow insulation into the wall cavity, it is filled with air, and the air creates a resonant space that actually amplifies incident sound. Loosely-packed cellulose has good sound absorption properties, and because it isn't a skin or eye irritant, it's safer to install than fiberglass.

Cellulose insulation is the most prone to settling and will undergo a 20 percent loss of R-value due to settling. R-value measures the relative effectiveness of insulation per inch.

Without proper ventilation, a home can build up too much moisture, especially in the attic (warm air rises), which can cause mold problems and, overall, lower indoor air quality. This is not to say that if you have mold in your home, too much insulation is the culprit.

Fiberglass batts, however, are less expensive, costing on average $0. 30 to $0. 40 a square foot for 6 inches of insulation. Installation costs for blown-in insulation costs around $2 a square foot, where installation costs for batts is around $1 a square foot.

For loose-fill cellulose, this translates to a total depth ranging from 8 inches up to 16 inches. Fortunately, attic insulation can be upgraded simply by adding more to achieve the recommended total depth in inches, without removing existing insulation.

Batts, or rolls, are large blankets of insulation that are made from either fiberglass or cotton. Blown insulation is accomplished by blowing out chunks of either fiberglass or cellulose from the hose of a blowing machine. The main benefit of blown insulation is that it is a much more consistent type of insulation.

The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.

If blown-in insulation is used, control the height or thickness of the layers so boards can by laid over top without having to compact the filler.

If this sounds like what you have, it is likely cellulose insulation, which contains a higher amount of recycled paper, without minerals. This means cellulose insulation does not contain asbestos and is a safe insulation, blown into the cavities.