MAXScanner engineering calculator
Composite Wall Thermal Resistance Calculator — Layers, U-Value & Heat Loss
Calculate series resistance of up to three plane-wall layers, overall U-value and steady heat flow including optional inside and outside film resistances.
Last updated: September 17, 2026
Results
Formula, example and assumptions
Rarea=Rsi+Σ(Li/ki)+Rso; U=1/Rarea; Q=U·A·ΔT.
A 100 mm insulation layer at k=0.04 W/mK contributes 2.5 m²K/W before films and other layers.
- One-dimensional steady conduction with uniform layer conductivities.
- Thermal bridges, moisture and contact resistances are excluded unless represented separately.
Frequently asked questions
What does this Composite Wall Thermal Resistance Calculator solve?
Calculate series resistance of up to three plane-wall layers, overall U-value and steady heat flow including optional inside and outside film resistances.
Which units should I use?
Use the units printed beside each input. Dimensionless ratios need no conversion; pressure inputs used in gas equations are absolute unless the field explicitly says differential.
Is this suitable for final engineering design?
Use it for transparent first-pass calculations and cross-checks. Final design should verify gas or fluid properties, geometry, loss data, equipment curves and the applicable engineering standard.