Cellulose Insulation Odor and Coverage
Any odor or void problems with loose-fill (blown-in) cellulose attic insulation?
A few customer reviews of the Greenfiber Sanctuary cellulose say it emits a terrible smell from their attics into their houses. They’re only a small percentage, and they may have gotten bad batches. I have an excellent air seal along my ceiling, and my attic is well-ventilated, but I also have an off-the-charts keen sense of smell. Have any of you found this product to smell bad?
A guy who used to install blown-in cellulose says he switched to other products because the cellulose dust was so thick while blowing it in, he couldn’t see well enough to avoid leaving some areas in the attic with “voids.” Would you be concerned about this?
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Replies
etting,
I've never had a problem with cellulose smelling, but it may be something that varies by supplier.
That the dust precludes the installer from doing a good job is a really odd argument.
Thank you, Malcolm. After asking my question, it occurred to me to watch some YouTube videos of cellulose being blown in, and they didn't look so dusty that one couldn't see how the insulation was being spread.
etting,
The installer's comment struck a nerve with me. GBA once featured a house build that used CLT and exterior foam, based largely on the advice of a neighbour who didn't believe you could use cellulose in walls. Over the years I've lost track of the things people in the trades have accepted as facts, when they were anything but, which had been passed on to them by others. It does people like you, trying to make informed decisions, a real disservice.
I have heard of cellulose smelling when wetted. perhaps those people have moisture issues in their attic.
Thank you. The reviews generally indicated that the cellulose had just been installed. I did read, however, that some pro installers apply it slightly wetted to keep the dust down.
I had Greenfiber cellulose damp applied in my walls and loose fill in the portions of my attic that are vented.
No smell from that of which I'm aware.
Before they put the loose fill in the attic there was a distinctive smell which I think was from either open or closed cell spray foam.
Thank you. I'm guessing from the customer reviews I've read that a small percentage of people get bad batches. Roughly 5% of the reviewers say the smell was so bad, it made their house almost unlivable. That 5% may be an underestimate of the frequency of batches that someone with a keen sense of smell would find troublesome, as many people don't notice smells that others sense quite strongly.
Cellulose is 99.9% wood fiber treated with boric acid to keep the insects and fire at bay. Really nothing smelly but since it is made from almost 100% post-consumer materials quality control could be a problem sometimes.
Consider big fiberglass might post silly stories in an effort to compete with a lower cost, greener product that better blocks air flow.
Note My cellulose was damp sprayed with no detectable smell.
Walta
Thank you, Walter. Customers who post reviews that report a bad smell most often describe it as smelling like diesel or kerosene.
GOOD cellulose is treated with borates, which have no significant odor, but CHEAP cellulose is treated partially or entirely with ammonium sulfate which apparently stinks like ammonia when wet.
I can't imagine what would make cellulose smell like diesel fuel.
I have heard that some brands and batches of cellulose are dustier than others, and that it's harder to get good-quality cellulose than it used to be.
Thank you, Michael. Paper absorbs and retains odors quite strongly. Some newspaper may have been stacked in a garage or warehouse where diesel was also present before it got recycled into cellulose insulation