Cellulose Blown-In Insulation is a wood fiber, fire-retardant insulation.

Four major types of loose-fill cellulose products have been developed under a variety of brand names. These are generally characterized as dry cellulose, spray applied cellulose, stabilized cellulose, and low dust cellulose. These types are used in different parts of a building and for different reasons.

Dry cellulose (loose fill):

Dry cellulose is used in retrofitting old homes by blowing the cellulose into holes drilled into the tops of the walls. It can also be blown into a new wall construction by using temporary retainers or netting that is clamped in place then removed once the cellulose has reached the appropriate density. This form of application does settle as much as 20% but the stated R-value of the cellulose is accurate after settling occurs. In addition, a dense-pack option can be used to reduce settling and further minimize air gaps. Dense-pack places pressure on the cavity, and should be done by an experienced installer.

Loose fill in walls is an antiquated technique of using cellulose in wall cavities. The home performance industry and its accrediting bodies support the dense-pack standard of insulating wall cavities, which does not settle. This method stops the stack effect and convective loops in wall cavities.

Spray-applied cellulose (wet-spray cellulose):

Spray-applied cellulose is used for applying cellulose to new wall construction. The differences are the addition of water to the cellulose while spraying as well as adding some kind of moisture retardant such as chlorine to prevent mold cultures. In some cases the insulation might also mix in a very small percentage of adhesive or activate a dry adhesive present in the cellulose. Wet-spray allows application without the need for a temporary retainer. In addition, wet-spray allows for an even better seal of the insulated cavity against air infiltration and eliminates settling problems. Wet-spray installation requires that the wall be allowed to dry for a minimum of 24 hours (or until maximum of 25% moisture is reached) before being covered.

Stabilized cellulose:

Stabilized cellulose is used most often in attic/roof insulation. It is applied with a very small amount of water to activate an adhesive of some kind. This reduces settling and decreases the amount of cellulose needed. This can prove advantageous at reducing the overall weight of the product on the ceiling drywall helping prevent possible sag. This application is ideal for sloped roofs and has been approved for 5:12 (41.66%) slopes.

Low-dust cellulose:

The last major type of cellulose insulation on the market is low-dust variety. Nuisance levels of dust are created during application of most types of dry insulation causing the need for simple dust masks to be worn during installation. This kind of cellulose has a small percentage of oil or similar dust dampener added. This may also be appropriate to homes where people are sensitive to newsprint or paper dust (though new dust will not be created after installation).

Thinking about going green? Cellulose is one of the greenest insulation products on the planet. Made from 85% recycled products and treated with fire-retardant chemicals and anti-mold products, cellulose is fast becoming a favorite product for LEED (Leadership in Energy & Environment Design) certified engineers and builders.

• Lightweight – By careful selection of stock and blending of chemicals, the density is maintained at 1.6 pounds per cubic foot area. This allows for greater protection at less weight.
• Long, Flexible Fibers – This allows Cellulose Wood Fiber Insulation to be blown easily into small cavities through openings as small as 5/8 of an inch.
• High R-Value – Cellulose has a higher R-value per inch than most types of insulating materials. It gives you greater protection with less material.
• Non-Corrosive – Cellulose Wood Fiber Insulation will not adversely affect any known type of building material.
• Helps Dissipate Moisture – The millions of microscopic air cells in Cellulose Insulation helps dissipate moisture by evaporation before it can collect to damage framing members, plaster or paint.
• Won't Settle – When properly installed, Cellulose Insulation will not settle in side walls.

In new construction, cellulose can be damp-spray applied. In this process, cellulose insulation is mixed with a water and glue like substance which allows it to adhere to plywood sheathing, much like foam. In new construction rooflines it can also be dense-packed.

The thermal performance of loose filled cellulose compares favorably to other types of attic insulation. The thermal conductivity of loose-fill cellulose is approximately 40 mW/m·K (an R-value of 3.8 per inch) which is about the same as or slightly better than glass wool or rock wool. This doesn't represent the whole picture of thermal performance. Other important aspects are how well the building envelope is sealed from air infiltration, convective airflows, and thermal bridging.

Cellulose is very good at fitting around items in walls like pipes and wiring leaving few air pockets that can reduce the overall efficiency of the wall. It also seals walls from air infiltration while providing the density to limit convection. The University of Colorado School of Architecture and Planning did a study that compared two seemingly identical test structures, one with cellulose and the other with fiberglass. The cellulose structure had used 26.4% less energy to heat. It also was shown to tighten the structure more than 30%. Subsequent real world surveys have cellulose performing 20-30% better at reducing energy used for heating than fiberglass.

• Lower energy bills
• More comfortable space
• Uniform temperature throughout your house
• Reduced outside noises