How thick should cellulose insulation be?
How thick should cellulose insulation be?
Cellulose is not unusual in this regard. Like many insulation materials, it provides an R-value of approximately R-3.5 per inch of thickness….Cellulose Insulation – A Smart Choice.
| Insulation Type | R-value per Inch of Thickness |
|---|---|
| Loose-fill fiberglass | 2.5 |
| Loose-fill rock wool | 2.8 |
| Loose-fill cellulose | 3.5 |
| Dense-pack cellulose | 4.0* |
What is R-value of dense-pack cellulose?
The R-value of cellulose is based mainly on its installed density, with denser installations generally delivering higher R-values. Loose-fill cellulose has an R-value of R-3.7 to R-3.8 per in., while damp-spray and dense-pack assemblies are rated at R-3.6 per in. or higher depending on its installed density.
How dense is dense-pack cellulose?
The difference is how tightly the cellulose is packed into the cavities, and you often can’t tell just by looking at it. We blow to a density of 3-1/2 lb. to 4 lb. per cu. ft., which feels like a very firm mattress.
How much dense-pack do I need?
In the Dense-Pack Insulation tool, include this density as the “Installed density” when solving for “Bag count”. The recommended dense-packed density for cellulose is 3.5 to 4.5 lb/ft3 (56 to 72 kg/m3) and for fiberglass 1.8 to 2.6 lb/ft3 (29 to 42 kg/m3).
How deep should cellulose insulation be in attic?
about 10 to 14 inches
The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.
What R-value is 12 inches of cellulose?
| R-value of Materials and Depths | ||
|---|---|---|
| Material | R-value/in | 12″ |
| Cellulose blown (attic) | 3.2 – 3.7 | 38.4 – 44.4 |
| Cellulose blown (wall) | 3.8 – 3.9 | 45.6 – 46.8 |
| Polystrene Board | 3.8 – 5.0 | 45.6 – 60.0 |
Is cellulose insulation cheaper than fiberglass?
When comparing blown-in insulation, both fiberglass and cellulose are nearly identical in price, both costing around $0.70 to $0.80 per square foot for 6 inches of insulation. Fiberglass batts, however, are less expensive, costing on average $0.30 to $0.40 a square foot for 6 inches of insulation.
Does dense pack cellulose need a vapor barrier?
Dense packing a wall does not eliminate the need for an air barrier in new construction. But in retrofit applications we often get so close that we can typically live without one.
Do you need a vapor barrier with cellulose insulation?
A common misconception is that vapor barriers are required in all insulation installations. With Modern’s Cellulose insulation, a vapor barrier is not recommended except in very cold weather or high moisture areas such as spas or pool buildings. Cellulose insulation has a high density compared to fiberglass.
How do you calculate cellulose insulation needed?
To determine how much cellulose insulation you need, take the square footage of the space and divide it by either the depth or the desired R-value.
What should the density of cellulose insulation be?
Therefore, in order to prevent settling, it is recommended to increase the density by 10% after filling the wall cavity (with a minimum density of 57 kg/m 3 ).
Is it good to use cellulose insulation in Canada?
When cellulose is densely blown (3.0lbs/ft3 or 48kg/m3 or greater) it is an excellent wall cavity insulation that provides a good R value at a reasonable cost. However, it is seldom used in Canada despite its reasonable cost and efficiency.
Are there any drawbacks to blowing in cellulose insulation?
There are also a few drawbacks to cellulose insulation: While settling is one of blown-in cellulose insulation’s advantages, this can also be a problem, mostly with walls. Over time, the insulation can pack down and form pockets above the settled areas. These pockets become thermal bridges, which transmit heat or cold into the house.
What can I use as an alternative to cellulose insulation?
One alternative is to pull down the drywall and use fiberglass batts. Cellulose insulation stands up reasonably well against insects and vermin because it is treated with borates.
Therefore, in order to prevent settling, it is recommended to increase the density by 10% after filling the wall cavity (with a minimum density of 57 kg/m 3 ).
When cellulose is densely blown (3.0lbs/ft3 or 48kg/m3 or greater) it is an excellent wall cavity insulation that provides a good R value at a reasonable cost. However, it is seldom used in Canada despite its reasonable cost and efficiency.
There are also a few drawbacks to cellulose insulation: While settling is one of blown-in cellulose insulation’s advantages, this can also be a problem, mostly with walls. Over time, the insulation can pack down and form pockets above the settled areas. These pockets become thermal bridges, which transmit heat or cold into the house.
One alternative is to pull down the drywall and use fiberglass batts. Cellulose insulation stands up reasonably well against insects and vermin because it is treated with borates.