Does timber construction increase fire risk compared to steel?

This is a common misconception. Mass timber (glulam, CLT) has predictable fire performance with a charring rate of 0.65 mm/min, maintaining structural integrity for extended periods.

This is a common misconception. Mass timber (glulam, CLT) has predictable fire performance with a charring rate of 0.65 mm/min, maintaining structural integrity for extended periods. Steel, by contrast, loses 50% of its strength at 550°C and can collapse suddenly without warning — requiring fire protection (intumescent paint or board encasement) for all structural members. In fire engineering terms, an unprotected steel beam may fail in 15–20 minutes, while an adequately sized timber beam can maintain load-bearing capacity for 60–90 minutes through charring alone. Both materials require appropriate fire design; neither is inherently 'safer'.

Why this matters

This question relates to Timber vs Steel: Full Lifecycle Environmental 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:

→ Timber vs Steel: Full Lifecycle Environmental Comparison

Related questions

• Which has lower embodied carbon — timber or steel?
• Is steel more recyclable than timber?
• How do timber and steel compare for operational energy?

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.