Cellulose Insulation
We install cellulose insulation
It is a good insulation product. We blow cellulose into the attics of homes and have done so since the 1970s. However, we do not install cellulose into walls. The cost of the equipment and extra labor increases the cost for the consumer. Instead, we use high density blown fiberglass. It has the same R-values and does not settle over time.
Some spray-in-place installers overstate cellulose insulation's R-values
They claim that cellulose can achieve an R-15 (even R-17). The truth is that cellulose cannot achieve these R-values.
Michigan cellulose companies (Applegate and Nuwool) fought proposed code changes that required R-15 in 2x4 walls. Why were they concerned? Their products could not meet the proposed higher R-value requirements in a standard 2x4 wall system.
Cellulose has a rating of only 3.7 R-values per inch. With a 2x4 (in actual measurements 1.5x3.5), the most R-values cellulose can achieve is R-13. Nuwool provides a table of R-values at the bottom of their web page showing that cellulose can only achieve R-13. Details from the same table have been pasted below (abbreviated):
Wall System |
R-Values |
2x4 |
R-13 |
2x6 |
R-21 |
Some cellulose insulation companies use their own definitions
"Convective loops." They say that fiberglass is "degraded by the convection forces that develop within the insulation material," hence a convective loop. [1] At the end of their article they do admit it happens when fiberglass insulation is "improperly installed." Couldn't the same be said of cellulose? If convective loops could exist (never mind the use of building wraps) in improperly installed fiberglass, they could also exist in improperly installed cellulose, foam, etc.
"Effective R-value." A term used by the cellulose industry to overstate the effectiveness of their materials. [2] "Effective R-value" (aka "mass effect") "offers almost no benefit" in Michigan 's climate. Recent studies have proven that cellulose does not stop air infiltration better than fiberglass.
Spray-in-place cellulose installers focus on the R-values in walls, not the primary place for heat loss, the ceiling. Why pay the extreme prices for the same R-value in walls? Instead, if you want to spend your money most effectively, increase the depth of insulation in your ceilings.
What do we recommend?
If you want the best insulation job for your money, we suggest the following options:
| Good | Best | |
| 2x4 | R-13 | R-15 |
| 2x6 | R-19 | R-21 |
| Ceilings | R-38: using a combination of fiberglass batt and high density blown fiberglass or cellulose | R-49: using a combination of fiberglass batt and high density blown fiberglass or cellulose |
| Standard | Vents between every rafter; Polyurethane foam around outlets | Vents between every rafter; Polyurethane foam around outlets |
| Options | Polyurethane foam around windows, doors, and sill plates | Polyurethane foam around windows, doors, and sill plates |
The video below shows how cellulose insulation is made. The video is not the highest quality, but it shows the process.
Notes:
1 http://www.nuwool.com/products/technical/convectiveloops.html
2 "The sunny Southwest,
particularly high-elevation areas of