How does spray polyurethane foam compare with glass fiber batts and blown-in cellulose?

Glass fiber batts will not stop air leakage (it might filter out some dirt and dust). Blown-in cellulose will slow down air leakage. Spray polyurethane foam will stop air leakage.dead. Glass fiber batts have an R-value of about 3.5 (1 inch thickness). Blown-in cellulose has and R-value of about 3 to 4 (1 inch thickness). Spray applied polyurethane foam has an R-value of 6.7 to 7 (1 inch thickness). Glass fiber batts can sag over time; blown-in cellulose can settle over time; both situations leave sections uninsulated and you'll feel colder because of it. Spray polyurethane foam completely adheres to wood and sheathing and is rigid; the result is a permanent barrier to heat loss and air entry. Spray polyurethane foam will add strength and rigidity to your house. Class fiber batts and blown-in cellulose will not.  more