How much insulation do I need?
For batts and rolls in attics, walls and floors. Find how many bags to buy.
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How this is calculated
We multiply the area by the number of layers, add a little extra for cuts around pipes and wiring, and divide by the coverage printed on the bag.
Coverage varies a lot by thickness, so always use the figure on the product you’re buying. Thicker, higher R-value batts cover less area per bag.
How much attic insulation is recommended?
In most of the US, the Department of Energy suggests R-49 to R-60 for attics in colder climates and R-30 to R-49 in warmer ones. That usually means two layers of batts laid crosswise.
Do I subtract joists and studs?
No. Batts are sized to fit between framing, and the coverage on the bag already accounts for that.