How to use
- Choose a project type and enter one or more areas.
- Enter package coverage from the insulation label.
- Use the R-value field as a note and verify local requirements separately.
Input guide
- Package coverage is square feet per bag, roll, or package.
- R-value target is recorded as a note only.
- Price per package is optional and not live market data.
Common mistakes
- Using wall square footage when measuring attic floor area.
- Assuming this chooses a code-compliant R-value.
- Ignoring blocked bays, ventilation, moisture, or obstructions.
Assumptions and limitations
- No local R-value code judgment is included.
- No electrical, vapor barrier, ventilation, moisture, mold, or pest advice is included.
- Waste is a simple planning allowance.
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Formula
- Total area = sum of each area length x width.
- Area to buy = total area x (1 + waste percent / 100).
- Packages needed = area to buy / package coverage, rounded up.
- Estimated cost = packages x optional user-entered price.
Example
A 600 sq ft attic with 10% waste and packages covering 48 sq ft needs 14 packages because 660 / 48 rounds up.
FAQ
Does this tell me what R-value I need?
No. It records your target as a note only. Verify climate zone and local requirements before buying.
Can this estimate rolls and bags?
Yes, as long as you enter the coverage per package from the label.