【How-to】How much does it cost to insulate a 800 sq ft house

If you’re aiming for R-30 (a common recommended value for attics per the Home Depot chart), the GreenFiber chart gives 40.8 bags per 1,000 square feet of gross coverage. Divide the measured square footage you obtained by 1,000 square feet to obtain the multiplication factor: 1,500 square feet/1,000 square feet = 1.5.