To achieve R-40, we install 12” of cellulose insulation. To achieve R-50, we install 15” of cellulose insulation.
To calculate the cost of cellulose insulation for your project, you will need to determine how much insulation you will need. To do so, take the square footage of the space and divide it by either the depth or the desired R-value.
Using the known R- values per inch of each type of insulation, we know that to install R-38 you need from 10” to 12” of cellulose and 14” to 17” of fiberglass. For an accurate depth for a given type of insulation there is a chart on the insulation bag noting the required depths for various R-values.
Blown-in insulation has an R value that ranges from 3.2 to 4 per inch depending on the type of material used and where it's installed in the house. This makes it one of the most efficient types of insulation available on the market today.
Many green builders aim for a ceiling rated at R-60, R-70, or even R-100. When it comes installing cellulose, the usual advice is to “pile it on.” Cellulose rated at R-60 is about 16 or 17 inches deep.
Attic Insulation
In colder climates, attics should have a minimum of R-49 insulation, which is equivalent to about 16 inches of fiberglass insulation. Warmer regions may require R-38 or higher, translating to at least 12 inches of insulation.
Cellulose content is calculated from the difference between ADF and ADL, hemicellulose from the difference between NDF and ADF. Lignin content is expressed as ADL and holocellulose was determined by addition of cellulose with hemicellulose [22].
However, like other loose fill insulation, it also has a tendency to settle over time, reducing its R-value and its ability to prevent air movement.
Fiberglass and rock wool batts—2x4 walls can hold R-13 or R-15 batts; 2x6 walls can have R-19 or R-21 products. Generally, batt insulation is the least expensive wall insulation material but requires careful installation for effective performance (see page 4).
DuPont™ Tyvek® ThermaWrap™ R5. 0 offers the air and water management benefits of all DuPont™ Tyvek® weather barriers with an R-value of 5.0. Compared to other exterior insulation products, the unique structure of Tyvek® ThermaWrap™ R5.
Blown-In Insulation: Loose-fill or blown-in insulation may require 10 to 12 inches to reach R30, depending on the material (fiberglass, cellulose, or mineral wool).
– Fiberglass insulation typically has an R-value of 2.2-2.9 per inch. – Mineral wool insulation has an R-value of 3.0-3.3 per inch. – Cellulose insulation has an R-value of 3.2-3.8 per inch. As you can see, cellulose insulation falls within the range of other popular insulation materials in terms of R-value per inch.
R-value measures insulation's heat resistance, with higher values indicating better performance. R38 insulation has a higher R-value than R30, providing greater resistance to heat flow. This increased resistance translates to improved energy efficiency and better temperature regulation in homes.
Cellulose insulation R value per inch is variable, but most cellulose insulation products offer R3. 5-R3. 7 per inch. So, if you need to reach R30 in your attic, you'll need a significant thickness—anywhere from 8.1 to 8.6 inches of depth.
R 40: Thickness that oscillates between 13 and 15 inches. R 50: Thickness that oscillates between 15 and 19 inches. R 60: Thickness that oscillates between 19 and 22 inches.
The optimal R-value for most homes is 30, but you can go as high as 38 if you live in a tropical climate. Anything higher than 38 indicates an over-insulated space. While you might think that too much insulation can't be bad, there are some significant consequences to consider.
How deep should cellulose insulation be in my attic? According to Energystar.gov, most attics' recommended cellulose insulation level is to insulate to R-38 (about 10 to 14 inches).
Closed cell spray foam has an R-value of R-7 per inch. In comparison, open cell spray foam has an R-value of R-3.8 per inch. Additionally, the materials have decidedly different densities.
If the federal recommendation is R60, then you can save yourself plenty of money on energy bills and HVAC repairs by having a minimum of R60 installed. This can be any combination of batts and blown-in insulation.
Cellulose rated at R-60 is about 16 or 17 inches deep. Cellulose rated at R-100 is about 27 or 28 inches deep.
At 3.5 per inch of material, the R-value of blown-in cellulose is 23% better per inch than fiberglass batts! According to research done at the Oak Ridge National Lab, fiberglass loses up to 50% of its R-value in very cold conditions; making cellulose a better choice for homes in northern climates.
Insulation R-value Per Inch:
Cellulose insulation – in wall cavities and cathedral ceilings, provides up to R3. 7 per inch (approximately R-12.8 for a 2X4 wall). NOTE: In flat ceilings with an attic above, height is not a restricting factor and both fiber glass and cellulose can insulate to beyond R-60.