Engineering guidelines for calculating roof and wall panel thickness based on TS 825 climate zones, target thermal transmittance (U-values), and condensation control.
Specifying sandwich panel thickness requires engineering rigor rather than simply choosing the cheapest unit price. Undersized panels lead to internal condensation, severe HVAC energy losses, and regulatory non-compliance.
1. Climate Zones & Target U-Values
Because warm air rises, roofs account for 40-50% of structural thermal losses. Roof panels should invariably be specified 1 to 2 thickness tiers above wall cladding.
Comprehensive Engineering Comparison Matrix
| Panel Thickness | PIR U-Value (W/m²K) | Rock Wool U-Value (W/m²K) | Recommended Application |
|---|---|---|---|
| 40 mm | 0.52 W/m²K | 0.88 W/m²K | Mild Climate Walls / Ambient Sheds |
| 50 mm | 0.42 W/m²K | 0.72 W/m²K | Temperate Walls / Mild Roofs |
| 60 mm | 0.35 W/m²K | 0.61 W/m²K | Temperate Climate Roofs (Industrial Standard) |
| 80 mm | 0.27 W/m²K | 0.46 W/m²K | Cold Climate Roofs / Chilled Rooms (+4°C) |
| 100 mm | 0.21 W/m²K | 0.37 W/m²K | Severe Climate Roofs / Cold Stores (0°C) |
For European and Middle Eastern industrial facilities, 60 mm PIR represents the ideal balanced specification for roofs, with 40-50 mm for exterior walls.
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Frequently Asked Questions
Is 40 mm panel suitable for industrial roofs? ▼
Only for unheated or open storage sheds. Conditioned industrial buildings require minimum 50-60 mm PIR to prevent winter condensation.