Can I use PIR insulation in a timber frame?

PIR (polyisocyanurate) can be used in timber frame construction but requires careful moisture management. PIR is vapour-closed (very low permeability), which means it acts as a vapour barrier wherever it is placed.

PIR (polyisocyanurate) can be used in timber frame construction but requires careful moisture management. PIR is vapour-closed (very low permeability), which means it acts as a vapour barrier wherever it is placed. In a timber frame wall, PIR should only be used on the cold side of the structure (externally) where it prevents interstitial condensation by keeping the timber frame warm. PIR between studs is risky because it creates cold bridges at the timber and prevents drying. If used between studs, a robust VCL on the warm side is essential and the assembly should be modelled with condensation risk analysis.

Why this matters

This question relates to Insulation for Timber Frame Homes: Materials & Performance Comparison, which covers the broader topic in detail. Understanding this specific aspect helps architects, builders, and timber dealers make informed specification decisions.

For full context and additional technical detail, see our comprehensive guide:

→ Insulation for Timber Frame Homes: Materials & Performance Comparison

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About this answer

This answer is part of the PuurModulair Knowledge Base — comprehensive timber specification guidance for architects, builders, and dealers across the UK, EU, and Scandinavia.