Cellulose insulation is considered both the most environmentally friendly insulation product and the most effective. On the other hand, the downside to this product is that it settles the most of any insulation option. This ultimately reduces the effectiveness of the product. So how much can cellulose insulation actually settle? We have completed a mountain of research to answer that question.
Cellulose insulation can settle up to 20%, but the general consensus is that settling ranges between 13-20%. Some factors will speed up settling. But don't worry! There are options to offset the settling.
Despite settling, cellulose insulation has the best performance of all insulation options. In the following, we discuss more about cellulose insulation, including how much it settles, how long it takes to settle, and whether too much insulation is a problem.
How much does cellulose insulation settle over time?
Cellulose insulation will settle up to 20%. In order to account for settling, the contractor needs to install 20% more. For instance, if the settled depth of the attic insulation should be 16 inches (R-60), which is ideal in colder climates, then the installer should be putting 19.2 inches into the attic.
Similarly, in warmer climates, 11.6 inches (R-38) is sufficient; the installer should be putting in 13.92 inches. The R-value necessary for proper heating and cooling depends on your climate.
Is cellulose insulation only used in attics?
Cellulose insulation is commonly installed in attic ceilings; however, you can also spray it in walls. Installers add small amounts of water as the cellulose is sprayed into the walls. This technique helps the cellulose adhere to the wall, providing a denser install.
The proper installation in walls is 3.0 - 3.5 PCF (pounds per cubic foot). As a result, manufacturers explain that this application will leave the insulation spring-loaded —and it is not supposed to settle. Improper installation is considered the cause if settlement does occur.
What exactly is R-value and how does it affect cellulose insulation installation?
All insulation has an R-value. Each area of the home has a different R-value requirement; this depends greatly on the climate in which you live. The R-value is defined as the capacity of an insulating material to resist heat flow.
The higher the R-value, the greater the insulating power. In other words, thermal performance is dependent on the R-value rating of insulation.
Federal guidelines for installation require compensation for cellulose insulation settling. If the cellulose insulation is not installed with the proper R-value after compensating for settling, then the cellulose insulation will not work at maximum capacity. Contractors are expected to display an R-value chart in attics where they install cellulose.
For more about R-value, check out our blog, "Does Cellulose Insulation Lose R-Value Over Time?"
How long does it take for blown-in insulation to settle?
Cellulose insulation is made of recycled newspaper and cardboard particles. It is treated with the preservative borate to protect against termites and other creatures that may break down wood. Because the product is made from paper it is more susceptible to settling.
Blown-in insulation settles over weeks, months, and even years as the house settles. Often, the majority of the settling will occur within the first few weeks of installation.
Several factors will accelerate the process, including:
- Bright lights in the attic
- Chimney insulation
- Amount of heat transfer that occurs
An experienced cellulose installation contractor will know how to compensate for these items and seal up areas that could cause potential heat loss.
How do you know if it's the right amount of cellulose insulation in your attic?
According to cellulose.org (the cellulose installation manufacturer's association), federal guidelines require compensation for the settling:
Every manufacturer is required to include a chart on their packaging to list the depth required to achieve desired R-values. Additionally, professional insulation installers must display a similar chart in the attic verifying the required depth of the insulation has been met.
These guidelines are vital to understanding the requirements for insulation to work properly in your area.
If you own a new home, make sure that the contractor left the proper signage regarding your insulation. If you are not sure what the proper depths are for your area, check local requirements.
A licensed contractor can likely provide a free estimate to check on proper insulation depths. Make sure to get more than one estimate in order to compare answers and know that you are getting a fair deal.
Should you use a contractor or do it yourself?
If you have ever watched insulation be blown-in, it looks like a simple job. But you must install insulation correctly or it doesn't work. Often, it costs less for a contractor to do it correctly the first time than to have to go back and fix something that is messed up.
Licensed contractors, who specialize in cellulose, have specific guidelines to follow to get proper coverage. In our opinion, a contractor is a safer choice. Make sure to get line-item estimates; this will help to dispel any confusion about what you are getting.
On the other hand, if you do choose to do it yourself, you can rent the blow-in insulation machine from your local building supply stores. You will want to wear a respirator and protective clothing.
Is too much attic insulation bad?
Yes, an attic can have too much insulation. A home needs to breathe. This means that moisture needs to be able to escape. Moisture exists in all homes with running water, from dishwashers to showers; that moisture needs to go somewhere.
In addition, some climates are much more naturally humid than others. If the house is too tight and there is too much insulation, the moisture gets caught in the insulation and grows mold.
For more regarding mold and cellulose, check out our blog, "Is Cellulose Insulation Mold-Resistant?"
A home needs to breathe also means that some air needs to come in from outside. Too tight of a house can actually mess up appliances; it also affects proper heating and cooling. Too much insulation can make it so that air does not circulate properly.
Can attic insulation be compressed?
You can only slightly compress cellulose attic insulation. This technique is called dense packing and allows room for more insulation. When installing cellulose insulation, dense packing is considered standard procedure.
As a result, this application technique lowers the risk of settling. Extra air is removed when compression is used. In contrast, too much compression will result in losing the attic's ability to breathe properly (as explained above) and causes moisture issues.
If you want to know about other types of insulation, check out our blog, "9 Types Of Thermal Insulation You Should Know."
In conclusion, cellulose insulation has a reputation for settling; however, it remains the best choice for attic insulation. It is the best for the environment. It is also the best breathable thermal barrier on the market.
Be aware of local requirements for R-values. Make sure that your attic adds up to the right amount, not too much and not too little. The right amount of insulation will save on your heating and cooling bills and keep your home breathing happily.