Here's Why Cellulose Insulation is Best for Your Attic | Dollar for dollar, cellulose has more insulating power
"R-value" (an expression of heat transfer resistance) is the standard for measuring insulation performance. At R 3.6 to 3.8 per inch, cellulose insulation is considerably better than most mineral fiber blowing wools. Some materials, such as foam plastics, may have higher R-per-inch ratings, but they are typically much more expensive.
Remember! Compare costs on the basis of the total R-value of the installation, not on the price of individual bags, boxes, or rolls. When you do, you'll find that cellulose insulation gives you the most heat transfer resistance for the money.