Insulation Calculator
Updated Formulas shown
Check the coverage printed on the bag — it varies with R-value. A 40 × 30 ft attic floor with R-30 batts at 49 ft² per bag needs 26 bags.
Bags / rolls
26
- Area incl. waste
- 1,260 ft²
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Frequently asked questions
What R-value do I need in my attic?
The DOE recommends R-30 to R-60 for attics depending on climate zone; R-13 to R-21 for 2×4 and 2×6 walls.
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Estimates only. Check quantities with your supplier or contractor before ordering.