Cellulose insulation is made from recycled newspaper that has been treated with either sodium borate, boric acid, or ammonium sulfate. These chemicals are required to make the cellulose insulation fire resistant and also to repel rodents, mold and insects.
Cellulose insulation can still be flammable and we don’t have long-term results from studies regarding the chemical mixes that are applied. Cellulose insulation is also more expensive and can sag after it is installed but the spray-on insulation is easy and it is definitely a better choice than fiberglass.
The R-Value of cellulose insulation is high at around 3.7.
For more information about cellulose insulation check out CIMA – Cellulose Insulation Manufacturers Association but be aware that CIMA is not an independent website.