Blown Cellulose Insulation: Advantages
Blown cellulose insulation is a popular option for the owner builder when insulating the project. Fiberglass batt insulation has been the standard for many years. Recently, perhaps over the last 10 years, blown in has gain popularity and affordability. Most insulation contractors can offer cellulose as an option. It may still cost more than fiberglass batts, however, there are some distinct advantages.
No Gaps or Voids
This is the principal advantage of blown cellulose over fiberglass batts. The installation of cellulose allows the product to fill the wall cavity completely and envelope any wires, pipes, cables or framing voids. It creates a true insulated building envelope. A well insulated building reduces noise, keeps the cold out, the hot in and is a critical element to whole house performance.
Blown cellulose is normally treated with borate, a fire retardent that also acts as an insect repellent. This reduces the amount of bugs living in the walls and protects te building from fire. I have seen the tests done where they put direct flame to blown cellulose insulation and it will not burn. I have also seen tests where they set buildings on fire, side by side. The house insulated with blown cellulose stood for nearly an hour after the first building collapsed.
Video: Blown Cellulose Vs. Fiberglass
Less Air Movement in Walls
Combined with the the proper use of foam sealing, cellulose will reduce the amount of airflow through the walls. This is because a blown cellulose wall does not have room for air to travel freely. This is an additional fire deterrent. Fire need air. A sealed cavity that does not allow air movement will act to suffocate a fire if it starts. It is impossible to completely prevent those voids and gaps in a batt insulated wall.
Ease of Installation
Because the installation of blown-in is so simple, there is less chance that it won't be done well. Installers become proficient very quickly. One worker can man the hose, filling the cavities while the next follows with shears, shaving the excess material flush with the studs. The crew follows up by pulling the remaining blown cellulose insulation material back into the truck for re-use.
Blown cellulose insulation is composed entirely recycled newspapers, books, and bags, treated with fire retardent. It is important to a lot of people to used recycled products. If that is important to you as an owner builder, consider this option on those grounds as well.
It is important to have the project swept thoroughly prior to the insulation crew's arrival. Part of the blown in process is to save as much shaved material as possible. If there is debris; nails, trash, or other contaminents on the floor, the insulation crew is unable to recycle the shaved cellulose. This is not only wasteful but it also makes the job that much more difficult to clean up. It is also helpful to keep stocked drywall a minimum of 24 inches from any exterior walls. The crews need to get a large hose and other equipment right next to the wall.
Sometimes, the crews can get a little lazy at the end of the day and do a less than thorough clean up. Put your foot down. Do not allow insulation mess; it gives incoming trades an excuse to leave trash behind.
Don't Drywall over Wet Cellulose
The material blown into the walls is wet. Be certain to have the moisture levels tested before commencing with drywall. You don't want to trap moisture in the walls that can lead to mold growth. This is often part of the inspection process conducted by building officials, but not always.
Interior Walls or Sound Walls
Interior insulated sound walls are not considered critical to whole house performance, so often, fiberglass ( a less expensive product ) is used in lieu of netting and installing blown cellulose insulation. This is an owner builder decision. I would suggest however, if the owner builder is creating climate zones, they are much better off using cellulose and in all cases, cellulose does perform better than batts.
If Using Batts
If the owner builder does decide to use fiberglass batt insulation, be sure to use faced batts and monitor the
installation diligently. A properly installed fiberglass batt is still a good insulator and there are contractors that take
pride in a clean, complete installation. Seek them out, following the principles set forth on our
construction bid page.
Blown Cellulose Insulation is a product that contributes to overall performance of an energy efficient home.