What Is Cellulose Insulation Made Of?

Cellulose insulation is made primarily from recycled paper fibers combined with treatments that help the finished product meet fire-resistance and other performance requirements. Rogers Insulation installs CleanFiber®, which uses recycled cardboard and an all-borate fire-retardant treatment. For homeowners considering an upgrade, the useful questions are what the product contains, what its testing establishes, and how it will be installed.

If you are considering cellulose for your attic or walls, Rogers Insulation in Framingham can help you understand the material and discuss an installation plan for your home.

How Does Recycled Paper Become Insulation?

Manufacturers process recovered paper into a loose fibrous material that can be installed with blowing equipment. The fibers and the air spaces between them resist heat transfer, helping keep heat inside during Massachusetts winters and reducing heat gain during summer.

For the product Rogers installs, CleanFiber describes a process that separates recycled cardboard into fibers and removes contaminants before the material becomes insulation. Its published product information identifies approximately 90% recycled material. That percentage is specific to CleanFiber; it should not be assumed to describe every cellulose product.

The finished insulation is a manufactured building material. Processing, treatment, quality control, and installation instructions distinguish it from paper that has simply been shredded and placed in a wall.

Why Are Treatments Added?

Paper fibers need treatment to achieve the properties expected of an insulation product. CleanFiber uses a liquid, all-borate fire retardant infused into the fibers. Other cellulose products may use different treatment systems, including formulations containing ammonium sulfate.

“All-borate” describes the fire-retardant treatment, rather than the entire contents of the bag. CleanFiber’s safety data sheet also identifies cellulose pulp and a small amount of mineral oil. The product is a formulated insulation material, and the treatment description alone does not establish every performance characteristic or make it appropriate for every location.

Homeowners can review CleanFiber’s safety data sheet, coverage chart, and installation information to understand its ingredients, intended uses, handling precautions, and installation requirements. A safety data sheet is not necessarily a complete recipe, so specific composition claims should be checked against the relevant manufacturer documentation.

Is Treated Cellulose Fireproof?

Cellulose insulation must be evaluated as a treated product. The federal safety standard for cellulose insulation establishes requirements for resistance to flame propagation and smoldering combustion, along with corrosiveness and labeling requirements. It applies to covered consumer products installed by professionals as well as those sold for direct consumer installation.

Meeting a fire-resistance test does not make cellulose noncombustible or fireproof. The product must still be installed with the required protection and clearances around heat-producing equipment and components. Treatment also does not make it acceptable to bury unsafe wiring or ignore an installation restriction.

This distinction is especially relevant in older MetroWest homes. Before insulating a Colonial attic that contains legacy wiring, for example, the electrical conditions need to be evaluated. Rogers’ guide to knob-and-tube wiring and attic insulation explains why the condition of the house matters alongside the material chosen.

What Do Product Standards Tell You?

ASTM C739, the specification for cellulosic loose-fill insulation, addresses the composition and physical requirements of treated cellulose products intended for attics and enclosed spaces. Its requirements cover thermal resistance, fire-related performance, corrosiveness, fungi resistance, moisture absorption, and odor emission.

For a homeowner, those tests provide a more useful basis for evaluating a product than broad promises that it is “natural” or “chemical-free.” They address particular properties under defined conditions. They do not guarantee that insulation will stay dry beneath a leaking roof, stop mice from entering an attic, or perform properly when installed with gaps.

Documentation should match the product being proposed. A manufacturer’s compliance statement or test information is more informative than a general claim about cellulose as a category.

What About Dust, Moisture, and Pests?

CleanFiber describes its manufacturing process as producing low-dust insulation, but low-dust does not mean dust-free. Handling and blowing cellulose still require appropriate precautions. Before installation, discuss how the work area will be prepared, how openings to the living space will be managed, and what cleanup is included; the crew should follow the manufacturer’s safety instructions.

Moisture needs separate attention. Cellulose can hold water, and persistent wetting can reduce performance and affect surrounding materials. Fire-retardant or fungi-resistant treatments do not make it waterproof. If you have attic moisture or mold, the source needs to be investigated before additional insulation covers the area.

Likewise, insulation treatment should not be confused with pest exclusion. Even where a product has documented pest-related properties, entry points, active infestations, and contaminated materials require their own evaluation. Our article on common myths about blown-in cellulose insulation introduces these broader questions; the proposed product’s documentation should support any specific claim.

Is Attic Cellulose Different From Dense-Pack Wall Insulation?

The installation method changes with the location. In an accessible attic, loose-fill cellulose is distributed across the attic floor to the specified coverage and depth. In enclosed walls, a suitable product is packed into the cavities through access openings at the density specified for that application.

A 1960s Natick ranch with an open attic therefore needs a different work plan from an older Newton home with empty exterior walls. The installer must account for access, existing materials, moisture conditions, and the boundaries between heated rooms and unconditioned spaces.

The product’s instructions determine where and how it can be used. Rogers’ guide to dense-pack wall insulation explains the conditions that make closed-wall work appropriate and the obstacles that may need attention first.

How Deep Should Cellulose Be in an Attic?

The right depth depends on the target R-value and the insulation already in place. The Massachusetts Clean Energy Center identifies R-49 as the Mass Save attic insulation standard; your assessment and approved work scope establish the target for your home. Air sealing and any needed moisture repairs should come before additional insulation.

For an attic relying entirely on CleanFiber to provide R-49, the manufacturer’s attic coverage chart specifies 16.1 inches when installed and a minimum of 14.5 inches after settling. The installer must meet the specified coverage and material quantity as well as the depth. Normal settling is already accounted for in these figures.

Dry fiberglass batts in suitable condition can often remain beneath new cellulose. Their assessed R-value reduces the amount of CleanFiber needed: an existing R-19 layer would need approximately R-30 added to reach a combined R-49. Rogers can evaluate the existing insulation and calculate the appropriate top-up rather than treating every attic as an empty space.

What Should You Ask Before Approving the Work?

Rogers uses CleanFiber, but the installation plan still needs to fit your home. Ask why the proposed approach suits your attic or walls, what R-value is specified, how existing insulation is accounted for, and how the crew will confirm that the required amount has been installed.

The FTC’s guidance on buying home insulation explains that R-value measures resistance to heat flow and that installers must provide product fact sheets. The manufacturer’s coverage information and installation requirements help connect that stated performance to the work being proposed.

Then discuss the house itself. Does the attic need air sealing? Are there leaks or wiring concerns? Will wall access require siding repairs or interior patching? Understanding the ingredients is useful, but a complete proposal also explains how the material will work in the space being insulated.

Discuss the Material and the Installation Together

The CleanFiber cellulose Rogers installs combines recycled cardboard fibers with an all-borate fire-retardant treatment. Its value in your home depends on installing it correctly after addressing conditions that could undermine the work.

Rogers Insulation helps homeowners in Framingham, Natick, Newton, and surrounding MetroWest communities evaluate insulation and air-sealing improvements. If you would like to discuss your attic or walls, call (508) 875-3700 or contact our Framingham office for an assessment or estimate.