A material's R-value is a measurement used to gauge the amount of heat flow through the material, according to AskThe Builder.com. Higher numbers indicate higher insulating capabilities. Currently, both blown insulation and fiberglass insulation are available in varying R-values.
Perhaps one of the biggest differences between these types of insulation is their means of application. Fiberglass is traditionally available in thick rolls that are unrolled, cut and placed into a desired location, while blown insulation comes in a canister and is dispelled from the canister to a location via blowing agents.
Many blown types of spray polyurethane foam insulation and other types of blown-in insulation are extremely flammable. Fiberglass insulation on the other hand, does not support combustion as easily, according to AskThe Builder.com.
According to R-Value.net, most blown-in insulation is two to three inches thinner than fiberglass insulation with the same R-value. One of the drawbacks to blown-in cellulose insulation is that it can cause corrosion on metals it comes into contact with, if it is improperly installed.
Blown-in cellulose insulation consists of around 75 percent recycled materials, while most fiberglass insulation only contains around 35 percent recycled materials according to Houle Insulation.