Wall R-Value Stack Calculator
Total R and U of a wall assembly from up to four layers plus air films.
Series resistances simply add — like resistors. The air films (0.17 combined) are free R-value every wall gets; thermal bridges through studs are the asterisk.
Formula
Wall R-Value Stack Calculator is a free wall r value for HVAC designers, technicians and energy auditors — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Wall R-Value Stack Calculator
Total R and U of a wall assembly from up to four layers plus air films. The calculation implements R_total = R_si(0.13) + ΣR_layers + R_so(0.04); U = 1/R_total (ISO 6946 — building component thermal resistance). Series resistances simply add — like resistors. The air films (0.17 combined) are free R-value every wall gets; thermal bridges through studs are the asterisk.
How to use Wall R-Value Stack Calculator
- 1Enter Layer 1 R (e.g. brick 230mm ≈ 0.3) in m²K/W.
- 2Enter Layer 2 R (e.g. XPS 50mm ≈ 1.5) in m²K/W.
- 3Enter Layer 3 R (e.g. plaster ≈ 0.06) in m²K/W.
- 4Enter Layer 4 R (0 if none) in m²K/W.
- 5Read Total R (with films), Assembly U-value instantly — no submit button needed.
Why use Wall R-Value Stack Calculator?
- ✓Implements the standard formula — R_total = R_si(0.13) + ΣR_layers + R_so(0.04); U = 1/R_total
- ✓Reference cited on-page: ISO 6946 — building component thermal resistance
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Wall R-Value Stack Calculator use?+
It computes R_total = R_si(0.13) + ΣR_layers + R_so(0.04); U = 1/R_total, per ISO 6946 — building component thermal resistance. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Series resistances simply add — like resistors. The air films (0.17 combined) are free R-value every wall gets; thermal bridges through studs are the asterisk.
Is this based on ASHRAE methods?+
The calculations follow the standard ASHRAE/ISHRAE formulations cited under the result, simplified where industry practice does the same. For permit-grade design, confirm with the full code procedure.
Is the Wall R-Value Stack Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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