More importantly, it maintains its fire retardancy over the life of a home. Cellulose, made of ground up newspapers is organic and naturally flammable. Therefore, it is treated with chemicals such as borax or aluminum sulfate to make it fire resistant. Some of the cellulose insulation from the late 1970s was not thoroughly tested for fire safety prior to being installed. Corrosion Second, there are differences in the area of corrosion.
Fiber glass contains no chemicals that can corrode pipes and wiring.
On the other hand, when sulfates are used to treat cellulose for flammability, there have been documented cases where the chemicals have been shown to cause corrosion of pipes, wires or metal nailing plates for roof trusses. Moisture Absorption Third, fiber glass insulation does not absorb and retain moisture. If wet, it dries, retaining its original R-value. Cellulose is made of ground-up newspapers and it does absorb moisture. This is a real problem because it can mat down and permanently lose R-value.