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Thermal insulation

Layered thermal resistance

Nominal R and U for entered homogeneous layers.

Layered thermal resistance

Layers
Layer 1
m
W/(m·K)
Surface resistance

Nominal homogeneous-layer result only; it excludes bridges, fixings, moisture and design assessment.

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How to use this calculator

Method and boundary

Enter each layer using thickness and design λ or direct R in SI or US. Select the direct R unit in layer mode independently of length preference. Use the product's total R at the selected thickness, not R per inch. Include each layer once and record surface-resistance selection.

Material R = Σlayer R; total R = material R + selected Rsi/Rse; U = 1/total R

Example

A 0.1 m / 0.040 layer plus direct R = 0.5 gives material R = 3. With fixed Rsi 0.13 and Rse 0.04: R = 3.17 m²·K/W and U ≈ 0.315 W/(m²·K).

Surface mode adds fixed 0.13 and 0.04 values rather than selecting them for heat-flow direction or conditions. The model omits inhomogeneities, bridges, fixings, moisture and full standard corrections.

Read guide: How to calculate U-value from layers

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