So we’ve seen that insulation is great for temperature and sound (read more at Can Your Insulation Really Reduce Noise?). But which insulation? There are a number of players in the field – fiberglass (those pink batts we’re all familiar with), spray foam, and mineral wool, to name a few. But cellulose, let’s talk about it because it’s got a few smart things going for it.
What Makes Cellulose Unique?
Cellulose insulation is not some high-tech lab creation. It’s made up mostly of recycled paper, like old newspapers. Sounds simple, right? But that’s some of its genius. Here’s why it often gets a gold star:
- Eco-Warrior: This is a biggie. Recycled paper means fewer things in landfills. Producing cellulose also tends to require less energy than producing some other types of insulation, such as fiberglass. So it’s a greener option to begin with.
- Fills the Gaps (Literally!): Cellulose is typically blown in. Think of it as super-fluff filling all of the tiny nooks and crannies in your walls or attic. Fiberglass batts will have tiny gaps if not cut and fitted perfectly. Spray foam is also great at sealing, but cellulose does it in a different, typically more plant-based, manner. Those tiny gaps are where drafts and sound love slipping in, so a tight fill is key.
- Sound Muffling: Because it’s dense and fills voids so completely, cellulose is often a champ at sound deadening. It can be significantly better at silencing street noise or the TV in the next room than standard fiberglass batts.
- Fire Retardant: Paper and fire do not sound like a good mix. But cellulose insulation is fire retardant treated (usually with borates, naturally occurring minerals). This renders cellulose very effective at slowing the spread of fire. It will char, but won’t melt or burn quickly, giving you precious additional time.
- R-Value Power: “R-value” is simply a measure of how good insulation is at resisting the flow of heat. The higher, the better. Cellulose will have a high R-value per inch, typically a bit better than standard fiberglass. This enables it to give you great thermal performance without needing to be overly thick.
- Pest Annoyance: Same borates that give fire resistance? Pests like rodents and some insects simply don’t like them. No insulation is a complete pest-proof force field, but cellulose might be less attractive than some others.
How’s it Stack Up, Really?
- vs. Fiberglass: Cellulose will usually have a higher R-value per inch, fill spaces more completely (especially in old, irregular walls), and be better at sound dampening. Fiberglass can be cheaper upfront and is moisture-resistant by nature, though if cellulose gets wet and then dries, it will usually keep its characteristics.
- vs. Spray Foam: Spray foam boasts great air sealing qualities and a very good R-value per inch, especially closed-cell foam. It is, however, typically a more expensive product and is a chemical product. Cellulose offers a more plant-based, lower embodied energy alternative with excellent gap-filling ability, but it might require a bit more thickness to provide the same R-value as some foams.
- vs. Mineral Wool: Mineral wool is a fine insulator and also has the bonus qualities of being fireproof and soundproofing. Cellulose generally stands on its own on sound and may be less expensive, with the bonus of that high recycled content.
Is Cellulose the Only Answer?
Not necessarily. The “best” insulation can also depend greatly on your specific home, your budget, and what you’re trying to achieve. In a few situations, a combination of types is even the best route.
But if you’re looking for one that’s highly efficient, great for the environment, closes all gaps, and can really turn down the volume on the outside world, cellulose is certainly worth a long, hard look. It’s some pretty smart stuff.