Knowing that asbestos was once used in insulation makes everyone look twice at the materials lining the attic and walls. Cellulose looks like such a hodge podge of materials that knowing its composition is required for peace of mind.
So, let’s examine what cellulose actually is and how dangerous it is.
Cellulose insulation is composed of treated recycled paper. It does not contain asbestos.
Types and Composition of Cellulose Insulation
Cellulose is basically a plant fiber, which means there is no asbestos present.
Cellulose used for insulation is typically made from 75-85% hammer-milled recycled paper, which is often treated with fire retardant chemicals such as boric acid, borax, or ammonium sulfate.
A number of forms of cellulose insulation may be available on the market.
Dry-Blown or Loose-Fill Cellulose
Dry-blown or loose-fill cellulose insulation is unbound in any way. It is blown into wall, floor, or ceiling cavities. It can be used to insulate old homes or during new wall construction.
Dry-blown cellulose insulation may settle and form gaps in the insulation, so dense-pack dry-blown cellulose can be used to reduce settling.
Wet-sprayed cellulose is mixed with water during the spraying process, forming dense insulation. Moisture retardants (to prevent mold) or adhesives may be present in this type of cellulose insulation in small amounts.
Wet-sprayed cellulose is appropriate for use during the construction of new walls.
Stabilized cellulose is similar to wet-sprayed cellulose, but a small amount of water is added only to activate an adhesive to reduce settling.
Stabilized cellulose is ideal for attic and roof insulation, especially in sloped roofs as the adhesive reduces the weight of the insulation and reduces the chances of ceiling sagging.
Low-dust cellulose has a small amount of oil or dust dampener to reduce the amount of dust created during installation. This form is advantageous for people who are sensitive to paper dust.
Is Cellulose Insulation Toxic?
As cellulose insulation is comprised of particles of milled paper, workers may be at risk of inhaling particles during installation.
Similarly, the fire-retardant chemicals, such as boric acid, borax, and ammonium sulfate, may be toxic if consumed or inhaled, or may cause irritation when in contact with the skin.
However, a cellulose toxicity study report found that less than 0.1% of particles were small enough to be inhaled, and amounts of these particles were low at work sites.
Similarly, there is little evidence to suggest that cellulose insulation causes lower respiratory health conditions, and there does not seem to be evidence to suggest that the chemicals in cellulose insulation cause cancer.
So, while it is wise to be cautious when installing cellulose insulation (especially for those with skin sensitivities and asthma), there does not seem to be major cause for concern.
How Does This Material Provide Insulation?
Paper is known to be a good insulator as the plant fibers trap air and prevent convection (heat flow through liquids and gases). Since cellulose insulation is made of paper fibers, it makes sense that it is a good insulator too.
Cellulose also provides insulation by preventing the flow of heat from the inside of a building to the outside through conduction (heat flow through solid materials), by providing a barrier to the heat flow.
This resistance to heat flow means that insulation helps your home to stay warm in the winter and cool in the summer.
Differentiating Between Cellulose and Asbestos
In contrast to cellulose, asbestos is comprised of small fibrous silicate crystals.
Cellulose and asbestos can be difficult to distinguish visually. If you suspect that there is asbestos in your home, it is best to leave it undisturbed and contact a professional.
Asbestos insulation is usually light brown or white in color but may also be greyish brown or silver gold. It may appear fibrous or may look like fallen snow or with a pebble-like form.
Cellulose is usually green or pink, but may also be gray, and has the appearance of shredded paper.
Asbestos is more commonly found in houses built before the 1990s and may be found as insulation around steam pipes or in asbestos-containing vermiculite insulation.
It can also be found in other parts of your home such as in roofing felt for shingles, cement asbestos board siding, popcorn ceiling, or in building materials, such as paint and floor tiles.
Pros and Cons of Cellulose Insulation
While cellulose insulation does not contain asbestos, it is still important to consider if this is the right insulating material for your needs.
Some advantages of using cellulose insulation are:
- Cellulose has favorable thermal performance compared to other low-cost insulation, with an R-value of 3.2 to 3.8 per inch of thickness.
- It is good for fitting insulation around pipes and wiring and has the highest fire safety rating.
- It provides sound insulation as well as heat insulation.
- It cuts down on waste by recycling paper.
- The use of cellulose insulation can save money in the long term and may reduce the cost of energy consumption compared to other insulating materials such as fiberglass.
However, the following disadvantages should also be considered:
- As cellulose contains small particles, it can create dust that can blow into the house interior if fixtures and fittings are not properly sealed.
- For proper installation, it is necessary to hire an experienced installer with knowledge on how best to apply specific types of cellulose insulation, or there might be inconsistent/inadequate insulation.
- If it is not properly installed, it can lead to slumping in the ceiling due to settling.
- Loose cellulose weighs more than three times more than loose fiberglass per square foot.
- Wet spray-applied cellulose may result in mold buildup.
Overall, cellulose can be considered a good asbestos-free alternative for your insulation needs, so long as it is installed and maintained properly.