All costs based on R30 for one square foot.
Johns Manville Formaldehyde free fiberglass $0.60
Ultra Touch Cotton $1.57
Cocoon Cellulose $0.42
Spay Foam – $6.98
The spay foam is based on one inch thick costing $1.62 and having R7. Thus R30 is the crazy price of almost 7 bucks.
Clearly Cellulose is the winner. BTW it is the winner by far in terms of low embodied energy. We always recommend cellulose when possible to our clients. Sometimes it is not possible:
client is allergic to it
we need more R value per inch (in which case we pick salvaged PolyISO that has R6 vs. R4 for cellulose)
it is a humid or wet area (then we pick XEPS).
We don’t see any reason to recommend Fiberglass or Spray foam. One probably gives you cancer with the small shards of glass and the other is a petrochemical and poison mix (spray foam has Isocyanate)