Blown-In Insulation Calculator
Updated Formulas shown
Check the coverage chart on the bag for your target R-value. A 1,200 ft² attic at about 35 ft² per bag needs 36 bags.
Bags of blown-in insulation
36
- Area incl. waste
- 1,260 ft²
DOE recommends R-38 to R-60 in attics for most of the US. Most stores lend the blowing machine free with a bag purchase.
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Frequently asked questions
Fiberglass or cellulose?
Cellulose is denser and blocks air better; fiberglass doesn't settle as much and resists moisture. Both reach R-38+ in an attic.
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Estimates only. Check quantities with your supplier or contractor before ordering.