VALICALC · TECHNICAL REFERENCE

Thermal Conductivity & Layer R Reference

Compare authored conductivity scenarios at an editable flat-layer thickness. Read material-only R and conductance while keeping assembly heat loss separate.

SCENARIO MATRIX

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Homogeneous layer thickness (mm)

SELECTED REFERENCE

0.02 W/(m·K) scenario

Layer-only resistance: 5 m²·K/W
Assumed conductivity: 0.02 W/(m·K)
Entered layer thickness: 100 mm

All fields & cell provenance

Layer-only inverse resistance: 0.2 W/(m²·K)
Layer US R: 28.391 h·ft²·°F/BTU

Authored conductivity: Thermal resistance and conductivity definitions — Authored homogeneous plane-layer scenario, no material identity · verified 2026-10-07 · source value 0.02 W/(m·K) scenario.
Layer-only resistance: Thermal resistance and conductivity definitions — Authored homogeneous plane-layer scenario, no material identity · verified 2026-10-07.
Assumed conductivity: Thermal resistance and conductivity definitions — Authored homogeneous plane-layer scenario, no material identity · verified 2026-10-07.
Entered layer thickness: Thermal resistance and conductivity definitions — Authored homogeneous plane-layer scenario, no material identity · verified 2026-10-07.
Layer-only inverse resistance: Thermal resistance and conductivity definitions — Authored homogeneous plane-layer scenario, no material identity · verified 2026-10-07.
Layer US R: Thermal resistance and conductivity definitions — Authored homogeneous plane-layer scenario, no material identity · verified 2026-10-07.

v1.3.0 · verified 2026-10-07 · values use the valid conditions shown above

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0.02 W/(m·K) scenario5 m²·K/WBack to answer ↑

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Thermal Conductivity & Layer R Reference, metric display
Authored conductivity	Layer-only resistance	Assumed conductivity	Entered layer thickness
0.1 W/(m·K) scenario	1 m²·K/W	0.1 W/(m·K)	100 mm
0.02 W/(m·K) scenario	5 m²·K/W	0.02 W/(m·K)	100 mm
0.03 W/(m·K) scenario	3.333 m²·K/W	0.03 W/(m·K)	100 mm
0.04 W/(m·K) scenario	2.5 m²·K/W	0.04 W/(m·K)	100 mm
0.05 W/(m·K) scenario	2 m²·K/W	0.05 W/(m·K)	100 mm
0.06 W/(m·K) scenario	1.667 m²·K/W	0.06 W/(m·K)	100 mm
0.08 W/(m·K) scenario	1.25 m²·K/W	0.08 W/(m·K)	100 mm
0.15 W/(m·K) scenario	0.667 m²·K/W	0.15 W/(m·K)	100 mm
0.025 W/(m·K) scenario	4 m²·K/W	0.025 W/(m·K)	100 mm
0.035 W/(m·K) scenario	2.857 m²·K/W	0.035 W/(m·K)	100 mm

0.1 W/(m·K) scenario

Layer-only resistance: 1 m²·K/W
Assumed conductivity: 0.1 W/(m·K)
Entered layer thickness: 100 mm

More dimensions

Layer-only inverse resistance: 1 W/(m²·K)
Layer US R: 5.678 h·ft²·°F/BTU

0.02 W/(m·K) scenario

Layer-only resistance: 5 m²·K/W
Assumed conductivity: 0.02 W/(m·K)
Entered layer thickness: 100 mm

More dimensions

Layer-only inverse resistance: 0.2 W/(m²·K)
Layer US R: 28.391 h·ft²·°F/BTU

0.03 W/(m·K) scenario

Layer-only resistance: 3.333 m²·K/W
Assumed conductivity: 0.03 W/(m·K)
Entered layer thickness: 100 mm

More dimensions

Layer-only inverse resistance: 0.3 W/(m²·K)
Layer US R: 18.928 h·ft²·°F/BTU

0.04 W/(m·K) scenario

Layer-only resistance: 2.5 m²·K/W
Assumed conductivity: 0.04 W/(m·K)
Entered layer thickness: 100 mm

More dimensions

Layer-only inverse resistance: 0.4 W/(m²·K)
Layer US R: 14.196 h·ft²·°F/BTU

0.05 W/(m·K) scenario

Layer-only resistance: 2 m²·K/W
Assumed conductivity: 0.05 W/(m·K)
Entered layer thickness: 100 mm

More dimensions

Layer-only inverse resistance: 0.5 W/(m²·K)
Layer US R: 11.357 h·ft²·°F/BTU

0.06 W/(m·K) scenario

Layer-only resistance: 1.667 m²·K/W
Assumed conductivity: 0.06 W/(m·K)
Entered layer thickness: 100 mm

More dimensions

Layer-only inverse resistance: 0.6 W/(m²·K)
Layer US R: 9.464 h·ft²·°F/BTU

0.08 W/(m·K) scenario

Layer-only resistance: 1.25 m²·K/W
Assumed conductivity: 0.08 W/(m·K)
Entered layer thickness: 100 mm

More dimensions

Layer-only inverse resistance: 0.8 W/(m²·K)
Layer US R: 7.098 h·ft²·°F/BTU

0.15 W/(m·K) scenario

Layer-only resistance: 0.667 m²·K/W
Assumed conductivity: 0.15 W/(m·K)
Entered layer thickness: 100 mm

More dimensions

Layer-only inverse resistance: 1.5 W/(m²·K)
Layer US R: 3.786 h·ft²·°F/BTU

0.025 W/(m·K) scenario

Layer-only resistance: 4 m²·K/W
Assumed conductivity: 0.025 W/(m·K)
Entered layer thickness: 100 mm

More dimensions

Layer-only inverse resistance: 0.25 W/(m²·K)
Layer US R: 22.713 h·ft²·°F/BTU

0.035 W/(m·K) scenario

Layer-only resistance: 2.857 m²·K/W
Assumed conductivity: 0.035 W/(m·K)
Entered layer thickness: 100 mm

More dimensions

Layer-only inverse resistance: 0.35 W/(m²·K)
Layer US R: 16.224 h·ft²·°F/BTU

How to use this data

Layer RSI=t[m]/λ[W/(m·K)]; inverse layer conductance=λ/t. US R=RSI/0.1761101838. The table deliberately avoids universal material conductivity claims.

CHECK THE METHOD

Worked example

At λ = 0.04 W/(m·K) and 100 mm, layer-only RSI is 2.5, US R about 14.1957 and conductance 0.4 W/(m²·K).

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Common lookup questions

What should I confirm before using this lookup?

Material-only resistance is not a whole-assembly rating. Framing, bridges, films, gaps, moisture and installation can change actual R/U; no climate-zone/code target is assigned.

TRACEABLE DATA

Sources, scope & verification

Dataset v1.3.0
Last verified: 2026-10-07

Ten authored λ values, not claimed properties of named insulation materials. Temperature, moisture and product λ must be verified separately.

Values are curated product facts or generated scenarios. Paid standards, complete catalogs and source diagrams are not reproduced. A verification date applies to this documented subset.

Thermal resistance and conductivity definitions ↗

Type A · US Bureau of Standards · Letter Circular 227: Thermal Insulation, 1927; definitions only

Original equations, chosen scenarios and generated values; no copied tables or drawings.

Full provenance & artifact record

Source checked: 2026-10-07
Use basis: authored-formula
Artifact SHA-256: No retained source artifact hash; see the stated source and verification record.