Build with SIPs to achieve your U value.
SIPs construction for walls and roofing and build to suit your desired U value result.
Calculations to achieve a U value of 0.18 for SIPs wall and roof construction.
Assumed build‑up (inside → outside)
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• 15 mm OSB
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• 140 mm EPS 70
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• 15 mm OSB
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• 50 mm EPS 70 (external)
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• Plus standard internal/external surface resistances.
Assumed λ‑values
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• OSB: (typical)
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• EPS 70 (grey)
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R‑values and U‑values Using and surface resistances:
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Case A – Grey EPS 70 (λ ≈ 0.031) • OSB (2 × 15 mm):
• 140 mm EPS:
• 50 mm EPS:
What this means for your 0.18 target
With grey EPS 70 (λ ≈ 0.031) you’re comfortably better than 0.18 W/m²K on the layer‑by‑layer calc.
