What are the disadvantages of cellulose insulation?

Author: Onie Dibbert III  |  Last update: Thursday, February 26, 2026

Cellulose insulation is heavy, and compacts any underlying insulation. Because cellulose insulation is paper, it absorbs moisture when it rains, and in areas of high humidity. Cellulose insulation degrades over time and has to be replaced. Cellulose insulation promotes the growth of mold & mildew in your attic.

What are the health issues with cellulose insulation?

Also, as that outside air moves through the cellulose, pollen, bacteria, and mold spores can cling to it. This becomes an issue when those particles are then circulated back through the home. If you suffer from allergies or asthma, this can cause a real problem.

Do mice like blown-in cellulose insulation?

It's also fire-resistant. Rodents generally are not drawn to cellulose insulation, either.

Why not to use cellulose insulation?

While cellulose insulation offers many benefits, its susceptibility to moisture damage is a notable drawback. If exposed to moisture, the paper fibers can absorb water, leading to mold growth, reduced insulation effectiveness, and potential structural damage to the building.

Does cellulose insulation get moldy?

In addition to losing effectiveness, wet cellulose can also encourage the growth of mold and mildew, contaminate your indoor air with mold spores and lead to structural problems as wood framing begins to rot.

What are the pros and cons of cellulose insulation?

What is the most mold resistant insulation?

Fiberglass insulation is constructed of tiny shards of glass that form pockets to trap air and help restrict the transfer of heat. Its naturally mold resistant in that the material itself is not a food source for mold.

How many years does cellulose insulation last?

Cellulose Insulation

The typical lifespan is 20 to 30 years, with degradation beginning as early as 15 years after installation. As with other types of insulation, severe weather or outside interference can reduce the lifespan. Note: cellulose is often used as supplementary insulation.

Which is better attic insulation, cellulose or fiberglass?

Both cellulose and fiberglass are energy-efficient insulation materials, but cellulose has a slight edge due to its higher R-value. The R-value for cellulose insulation is approximately 3.2 to 3.8 per inch, while fiberglass insulation typically has an R-value of 2.2 to 2.7 per inch.

What happens if cellulose insulation gets wet?

Compression and Settling

Cellulose insulation is designed as a loose-fill product. It relies on the 'fluff' of its fibers to create a seamless thermal barrier. However, when saturated with water: The weight of the fibers increases significantly.

What is the best insulation for the attic?

Fiberglass batt is considered to be the best insulation for attics. Compared to other insulation materials, it is the cheapest and easiest to install. Fiberglass batt is also incredibly energy efficient, as it helps to slow the spread of hot and cold air.

What is the best brand of cellulose insulation?

The best manufacturers of cellulose insulation include GreenFiber, Insulmax, Applegate, and Nu-Wool. RetroFoam of Michigan has more than 17 years of experience specializing in injection and spray foam insulations. While we specialize in foam, we have dealt with cellulose in homes that needed new or updated insulation.

What is the most rodent proof insulation?

Here are the 3 insulation materials to consider if you want to avoid falling victim to mice, field mice and other rodents:
  • Mesh screens to prevent rodent intrusion. ...
  • Cellulose, mouse proof insulation. ...
  • Hemp insulation, effective rodent resistant insulation. ...
  • Caulking is a rodent proof insulation solution.

Can rodents digest cellulose?

Rats and ruminants, like all mammals,lack the enzymes necessary to digest cellulose down to simple sugars, makingplant material a generally poor foodstuff.

What are the negative effects of cellulose?

Microcrystalline cellulose is generally safe, but some people may experience side effects such as gas, bloating, stomach cramps, and constipation. In rare cases, allergic reactions may occur, manifesting as rash, itching, swelling, severe dizziness, or trouble breathing.

What insulation is best for health?

Again, the off-gassing here can be a big problem. There are other types of insulation, but these are the most common. The best non-toxic insulation is either mineral wool or foam insulation inserts.

Can you put in too much cellulose insulation?

Too much insulation will leave humidity and moisture to accumulate in your attic space. This can lead to mold growth on your walls and insulation. There might also be water damage to the support beams in your home's roof.

Does mold grow on cellulose insulation?

A roof leak, pipe leak or high humidity can cause water to infiltrate the insulation, and insulated areas take a long time to dry back out. As a result, the blown-in cellulose insulation can become an incubator for mold and mildew.

How to dry out an attic in winter?

In winter, temporarily open windows just a little to allow warm moist air to leave the home and also allow cold, dry air to come in. For a short-term fix you can put a dehumidifier in your attic, but understand that you may be emptying it multiple times a day.

What happens if you breathe in cellulose insulation?

Unlike glass fibers, cellulose isn't dangerous to breathe. However, it can irritate your lungs. If you have pre-existing allergies, the dust of cellulose insulation can be obnoxious.

Do mice like cellulose insulation?

Cellulose Insulation and Its Composition

As the fire retardant can irritate rodents such as mice, they often avoid nesting within cellulose insulation.

What is the best insulation for an old house?

Spray foam: Open-cell or closed-cell spray foam can provide excellent insulation and air sealing in one application. Combination approach: Use spray foam to seal air leaks and fill odd-shaped cavities, then supplement with batt insulation for cost-effectiveness.

Does Lowe's rent a blown insulation machine?

If you'd like to install the insulation, rent a blow-in insulation machine from Lowe's.

What is the best attic insulation?

Loose-fill fiberglass attic insulation still experiences convection, but not nearly as much as old fiberglass used to. If you check with the North American Insulation Manufacturers Association, they'll assure you that fiberglass or mineral wool is definitely your best choice for attic insulation.

How long does it take for cellulose insulation smell to go away?

Odor from stabilized cellulose insulation is a very minor occurrence. It's rare, and when it does show up, it's faint and short lived. And, after the 2 to 3 day evaporative process is complete, the faint odor never returns.

Should I use cellulose or fiberglass insulation?

At 3.5 per inch of material, the R-value of blown-in cellulose is 23% better per inch than fiberglass batts! According to research done at the Oak Ridge National Lab, fiberglass loses up to 50% of its R-value in very cold conditions; making cellulose a better choice for homes in northern climates.

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