Foam One-Component spray foam is ordinarily not recommended to fill large cavities, why?
Handi-Foam One-Component spray foam is moisture-cured, therefore the spray foam closest to the surface, because it is exposed to the moisture in the air, will cure first, but the inside of the cavity may not cure properly and comepletely. However, by filling the cavity in layers allowing each layer of Spray Foam to cure would be a better option. Also, spraying mist from a water bottle will aid the curing process.