"Facts" about blown cellulose are mostly presented by manufacturers or distributors. Some of the "facts" are hype, or out right lies. 

Cellulose does burn in heat and flame. It produces noxious fumes, smoke and soot when heated to approx 300F and will ignite at higher temperatures. It will tend to smolder and choke itself out. 

More precise testing and data should be forthcoming. The test observations noted here came from crude home testing.


Does cellulose insulation cause mold?

Normally, probably not directly, when manufactured and installed correctly. The chemical treatment that makes it somewhat flame retardant also makes it somewhat resistant to bacterial growth. That in mind, both my homes have been damages by burning cellulose insulation. Without the cellulose, there would have been no fire damage. But, there were mitigating circumstances in both cases. It is mostly treated with boric acid to resist flammability, which  inadvertently makes it resistant to bacterial growth. Considered relatively harmless to humans, when wet, it is has been shown to be corrosive to metals, but again this requires some other failure to create such a condition. Supposedly, it doesn't degrade as rapidly as fiberglass, (the wool's binders) and is less likely to become airborne over time than wool fiberglass. In our home this would prove inaccurate. I don't know how much of the material provided a "food source" for the actual mold growth problem in our home, but most certainly, cellulose created conditions for mold growth, but builder errors made the cellulose a problem.

I would personally not want a home with cellulose insulation in it again, but that's just from personal bad experiences. I think it is relatively safe material assuming things are done correctly. That being said, it is fortunate building inspectors and supervisors don't inspect new commercial airline manufacturing and maintenance, where "assuming" things are done correctly just doesn't pass. 

Remember for high levels of cellulose to become a contamination problem (normally it isn't) you usually need shoddy construction, failure to comply with codes, and general incompetence in installing the material see: Ryan Homes- Defects and Damages Breathing cellulose insulation dust particles, or any dust particles in excess, is not "perfectly safe" as some advertise the material to be. Our home burned the material, which was treated with Boric Acid  to reduce flammability. Accord to the MSDS on Boric Acid, this material is generally safe in original form, however its chemical properties change when heated, such as occurred when our cellulose burned and was simultaneously dispersed throughout the air producing toxic chemicals and gases. The Boric Acid converts to a toxic, potentially lethal chemical, in the environment created by the builder errors. Report data on conversion-Boric Acid heated (by burning the cellulose that contains the boric acid) converts to pyroboric acid (H2B4O7) at 285-320F, and Boric anhydride at higher temperatures. Cellulose burns at 454F, and also produces CO. There is no clear data analysis for burning the insulation fibers and dispersing the gases and byproducts in forced air. 

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