Insulating Your Home with Cellulose Fibre

Mineral wool and fibreglass may be more familiar options, but home insulation is rarely the most exciting renovation project to tackle. That said, it can make a noticeable difference on your heating bill and improve soundproofing in your walls. So why not choose a greener and more efficient material? Let’s take a closer look at cellulose.

What Is Cellulose?

Cellulose is a carbohydrate made up of a linear chain of D-glucose molecules. These macromolecules form microfibrils, which make up the walls of plant fibres. It is the main component of wood and one of the most abundant organic materials on Earth.

In industry, cellulose is used in many products, including textiles, paint, mortars, varnishes, food products, cosmetics, and building materials. In-home insulation, cellulose is especially valued because it can be made from recycled paper products and used as a loose-fill or sprayed insulation material.

How Is Plant Fibre Turned into Natural Insulation?

Photo : Bill McNeal

Cellulose insulation is usually made from wood fibre or recycled newspaper that has been shredded and processed. The material is then treated with mineral-based additives to help resist mould, corrosion, pests, and fire.

Cellulose can be installed in different ways:

• Blown-in cellulose: Applied dry, often in attics or wall cavities.

• Sprayed cellulose: Mixed with water and a binder before application.

• Cellulose panels: A more rigid form used in certain building applications.

One of the advantages of cellulose is that it can fill irregular cavities and cover the available space without requiring seams. This makes it useful for attics, wall cavities, and other areas where gaps can reduce insulation performance.

Thermal Resistance of Cellulose

Cellulose generally offers an R-value of approximately R-3.5 to R-3.8 per inch, depending on the product and installation density. By comparison, many fibreglass and mineral wool products offer similar or slightly different R-values depending on their form and density.

For insulation, the higher the R-value, the better the material resists heat flow. However, R-value is not the only factor that matters. Air sealing, moisture control, ventilation, and proper installation all play a major role in the final performance of an insulation project.

Because cellulose is sensitive to moisture, it is important to ensure that the building assembly is properly air-sealed and that a vapour barrier or vapour control layer is used where required by the local building code. Cellulose also has good soundproofing properties and is treated to improve fire resistance.

An Eco-Friendly Insulation Choice

Cellulose is often considered an eco-friendly insulation option because it is made from recycled material, is widely available, and has a lower embodied energy than some synthetic insulation products. However, it is worth noting that cellulose insulation is treated with additives, often borate-based compounds, to improve fire and mould resistance. These treatments are important for safety and durability, but they are part of the product’s overall environmental footprint. From an indoor air quality perspective, cellulose insulation is generally considered a low-emission material when properly installed. As with any insulation material, it is important to follow safety guidelines during installation and avoid leaving dust or debris in living areas.

How to Install Cellulose Insulation

Photo : Flickr- Pierre PaillePoutreEtCo

According to many building professionals, it is often best to hire a qualified insulation contractor, especially for attic work, dense-pack wall insulation, or projects that involve air sealing and ventilation corrections. Installing cellulose may look simple, but achieving an even depth, proper density, and good coverage takes experience.

Some home improvement centres rent or lend blowing machines when you buy cellulose insulation from them. This can make DIY installation possible for some homeowners, especially in open attics. However, the equipment can be heavy, the hose can be difficult to manage, and the job usually requires at least two people.

Before blowing cellulose, you should:

• Make sure the attic or work area is properly ventilated.

• Seal major air leaks before adding insulation.

• Avoid blocking soffit vents.

• Install baffles or air channels where needed to maintain ventilation.

• Use depth markers to measure the final insulation level.

• Wear proper protective equipment, including safety glasses, a dust mask or respirator, gloves, and work clothing.

One person usually feeds the cellulose into the machine, while the other directs the hose and blows the insulation evenly across the space. The work should begin in the farthest corner and move gradually back toward the access point. The goal is to create a consistent layer without thin spots, blocked vents, or compressed areas.