Cellulose insulation, a popular insulation material, is well-known as an environmentally friendly option because it is made out of mostly recycled paper. Because it is combined with chemicals like borax, cellulose insulation, despite being created from recycled paper, is also a fire-retardant material.
However, like all insulation materials, cellulose insulation has its own potential side effects that homeowners should be aware of before installation.
Among the various types of insulation, loose-fill and dense-pack cellulose insulation are the two most common forms, contrasting with options like fiberglass insulation.
While cellulose is often preferred for its eco-friendly attributes, it’s important to consider how it compares in terms of durability and long-term effectiveness against other materials like fiberglass.
Attics commonly employ loose-fill cellulose insulation, whereas walls and ceilings use dense-pack cellulose insulation. Blown-in cellulose is loose-fill and dense-pack cellulose fitted with a blowing machine.
However, health dangers for cellulose installers and cellulose-insulated building occupants have been identified. Some experts oppose its use.
Is Cellulose Insulation Safe to Breathe?
The majority of cellulose insulation is made from ripped-up, recycled newspaper. Other fragments of recycled paper fibre may be present, but it is almost typically newspaper. When applying it, is cellulose insulation safe to breathe? The answer is yes, it is totally safe.

If you breathe it in, very fine fibers pose no risk of entering your respiratory system or causing any long-term damage. However, breathing in a significant amount of dust may cause minor irritation but nothing more.
Is Cellulose Insulation Flammable?
To create cellulose insulation, waste paper is milled and treated with flame retardant chemicals, most often boric acid and sometimes ammonium sulfate, enhancing its safety against fire hazards.
Despite these treatments, homeowners should be vigilant about the potential for cellulose insulation to absorb moisture, which can reduce its effectiveness and potentially lead to mold growth.
However, despite these treatments, it’s important to note that cellulose insulation, like many insulation materials, can still be a fire hazard under certain conditions. Firefighters even stated that cellulose insulation could be a cause of fire.
Additionally, the dust from cellulose insulation can be an irritant during installation and maintenance, necessitating proper safety measures to protect the respiratory system of those involved.
If one house with cellulose insulation once caught smouldering embers hidden in the insulation, as its nature to preserve heat, it could reignite inside the walls, allowing the fire to spread across the building or igniting a new fire.
Some Disadvantages of Cellulose Insulation to Consider
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- If you use dense-packed cellulose insulation, the piece could be spread all around your house
Any gaps in the wall cavities, such as electrical outlets, might allow dense-packed cellulose insulation to leak into the house. Some cellulose dust will be recirculated throughout the house over time in homes with furnace duct systems. When installing dense-pack cellulose insulation, extreme caution is required, although dust will still accumulate.
- It will eventually cause bridging
Bridging is the process of cellulose in walls separating over time and generating a gap. When this occurs, the holes enable air to flow in and out of the house, resulting in high monthly energy bills. It is important to maintain the cellulose insulation in your house.
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- If not kept dry, it could grow mold
Leaks in the home, condensation, or a lack of air seal, can all cause your cellulose insulation to grow mold. After absorbing the water, the material dries slowly, causing it to degrade and sediment. The water will also destroy the chemical fire treatment employed in the material. Your cellulose insulation must remain dry.
So, is cellulose insulation safe? It is relatively safe as long as you keep it in high maintenance.