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Insulation Calculator

Determine insulation type, quantity, and R-value requirements based on your climate zone, cavity depth, and local energy code.

Enter an assembly, climate zone, area, existing R-value, and insulation type to get a source-aware planning estimate. The app flags local cavity-depth limits, applies local loose-fill depth factors, estimates rough batt, loose-fill, rigid, or spray-foam quantities, and keeps code, vapor-retarder, fire, moisture, product-label, and AHJ limits visible.

Pro Tip: Use the result as a takeoff starting point. Product labels and manufacturer fact sheets control R-value, bag coverage, installed thickness, and loose-fill settled density; adopted local code and the authority having jurisdiction control compliance.

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Insulation Calculator
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How It Works

  1. Select a Zone

    Choose a climate zone or use the state lookup as a rough starting point. County-level zones, adopted code editions, amendments, and compliance paths can differ.

  2. Choose the Assembly

    Select the wall, attic, cathedral ceiling, crawlspace, basement, or rim-joist application. The app uses local target rows and does not approve a code path.

  3. Enter Area and Depth

    Enter the area and, where needed, the available cavity depth. Fixed 2x4 and 2x6 cavity depths are used only for local depth screening.

  4. Select a Material Row

    Choose a local batt, loose-fill, spray-foam, or rigid-board row. Replace R-value, package coverage, yield, and cost assumptions with the selected product label before purchase.

  5. Review Boundaries

    Check quantity, cavity-depth, vapor-retarder, source, moisture, fire, and safety warnings before involving the installer, designer, code official, or AHJ.

Built For

  • Homeowners roughing out attic or wall material quantities before reading product coverage charts.
  • Contractors doing an early takeoff before substituting product-label coverage and current supplier pricing.
  • DIYers comparing local cavity-depth screens for fiberglass, mineral wool, spray foam, and rigid foam.
  • Builders checking whether a local cavity-only row looks shallow before selecting a code path or continuous insulation strategy.
  • Energy or weatherization reviewers documenting source gaps before final code, rebate, moisture, and safety review.

Assumptions

  • Local material rows include nominal R per inch, loose-fill depth factors, coverage, rigid-board thickness, and material-only costs.
  • Climate-zone targets are simplified planning pointers, not adopted-code compliance results.
  • Vapor-retarder output is generic source-boundary guidance, not an assembly-specific moisture design.

Limitations

  • Does not model whole-wall U-factor, thermal bridging, UA tradeoff, performance path, fenestration, air leakage, duct location, rebate rules, or energy savings.
  • Does not approve vapor retarder placement, condensation safety, spray-foam exposure, ignition or thermal barrier requirements, asbestos/vermiculite work, electrical clearances, or combustion-air safety.

References

  • ICC 2021 IECC residential insulation table source pointer.
  • ENERGY STAR recommended home insulation R-values.
  • DOE Energy Saver insulation type and vapor-retarder guidance.
  • FTC/eCFR 16 CFR Part 460 R-value rule for product labels, fact sheets, and R-value claims.

Frequently Asked Questions

No. The app uses a simplified local target table as a planning screen. Your adopted IECC/IRC edition, local amendments, compliance path, exceptions, and AHJ interpretation control the actual requirement.
Use it only as a rough starting point. The FTC R-value rule and manufacturer labels/fact sheets control tested R-value, loose-fill settled density, initial installed thickness, and coverage area per package.
Loose-fill products have product-specific installed and settled thickness data. The app uses a local cellulose depth factor, but the selected product label coverage chart is the source to follow.
That depends on climate, assembly layers, exterior foam ratio, rain control, air sealing, existing vapor layers, and local code. The app gives generic boundary guidance only, not a final vapor or condensation design.
The app can show when a local R-per-inch row does not fit in a 3.5 in cavity, but product-specific thickness, compression behavior, whole-wall U-factor, continuous insulation, and the selected code path must be checked separately.
Do not assume that from this app. Product data, installed thickness, local code, ignition barrier, thermal barrier, combustion-air, and installer instructions control.
No. Costs are local material-only planning rows. Labor, access, removal, air sealing, baffles, PPE, fire barriers, disposal, permits, tax, and regional pricing are outside the app.
Disclaimer: Planning screen only. Verify adopted code, product labels, manufacturer instructions, moisture/vapor design, fire or ignition barrier requirements, jobsite hazards, and AHJ requirements before purchase or installation.

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Local R-target pointers, product-label quantity cautions, loose-fill notes, and vapor-retarder boundaries before code, installer, or AHJ review.

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