Cellulose is our preferred “blown fiber” insulation product. It’s recycled, fire-retardant, and is relatively cost effective. Blown cellulose is typically used in attics, dense-packed into existing walls, and often used in walls of new construction projects.
You’ll see the installers in the video (below) spraying it into new construction walls so that it sticks. This is “wet blown” cellulose, which introduces quite a bit of water into the wall assembly. We prefer to use the “net & spray” approach in new construction, which eliminates the majority of the moisture. This is similar to dense-packing existing walls. See more on this below.
Both loose fill and dense pack cellulose insulation are made from recycled wood-based materials and have a fire retardant additive. Loose fill is blown in to add insulation depth to areas such as attics, where the existing insulation is not sufficient. Made from recycled newsprint and other recycled paper, and treated with nontoxic fire retardants, cellulose insulation has been a tried and true method of insulating homes for decades. Its excellent sound insulating properties, its ability to provide an effective 1-hour fire rating, high R-value per inch, and industry leading environmental properties, makes cellulose a perfect choice for insulating attics and sidewalls.
- Cellulose takes less energy to make than any other insulation material. This is known as embodied energy and includes the total energy required to transport raw materials, manufacture and distribute the product. Fiberglass has up to 10 times more embodied energy than cellulose.
- Cellulose has the highest level of recycled content in the insulation industry – up to 85%. Cellulose insulation is made with recycled paper, paper that might otherwise end up in a landfill. Fiberglass has a maximum of 40% recycled content.
- Cellulose is regionally produced.
Cellulose insulation can be installed in a variety of applications. As with all fibrous insulation materials, it is critically important that air-sealing take place prior to insulation installation. Common air-leakage locations can be seen here, in this illustration. Click the diagram for a larger view. For additional information on air-leakage, visit the Building Science Basics section of the Greening Your Home section.
Cellulose is easily blown into attic spaces to create a solid layer of insulation across the ceiling surface. High R-values can be achieved affordably and quickly.Prior to installing additional insulation in your attic space, air-sealing should be performed first. By air-sealing the ceiling boundary, air leakage into the attic is eliminated, saving you money while maintaining a comfortable living environment.If this air-sealing step is skipped, warm air will continue to escape from your house, passing through the fibrous insulation.
New Walls – Net & Spray
When we install cellulose in walls of a new construction project, we first install a net, then densely pack the insulation behind the net. By taking this approach, we use less than 1% of the moisture typically used in the “wet spray” method.This netting also holds the cellulose in the wall cavities. In wet-spray installations, it is common to see cellulose that has fallen out of the wall cavities due to other trades (i.e. siding) banging on the walls. This often results in cavities that are poorly insulated, or lack insulation completely!
Existing Wall Dense-pack
In exisitng walls, we can fill wall cavities with cellulose by accessing the cavities with holes, either on the interior or exterior. A tube is inserted into the cavity, and cellulose is pumped into the cavity, filling it completely. By filling the wall cavities with cellulose, we can reduce the flow of heat throught this wall by over 1000%, making your home much more comfortable and efficient.