Understanding how structural materials behave in fire is fundamental to fire engineering design. This technical guide covers all major structural materials.. Material Behaviour in Fire Structural fire engineering is the discipline of ensuring buildings maintain their structural integrity during and after fire exposure. Each material behaves differently. Steel Critical temperature : 550°C (where steel loses approximately 50% of ambient temperature strength) Steel is strong but loses strength rapidly above 400°C Unprotected steel sections can reach critical temperature in 15 20 minutes in a standard fire Protection methods : intumescent paint, board systems, spray applied coatings, concrete encasement Concrete Excellent inherent fire resistance : Concrete cover protects reinforcement from heat transfer Minimum cover depths specified in BS EN 1992 1 2 Spalling — explosive spalling of high strength concrete is a key concern Polypropylene fibres added to HSC to prevent spalling (melts at 160°C creating vapour channels) Timber Charring rate approach : Timber burns at a predictable rate (typically 0.65 mm/min for softwood) BS EN 1995 1 2 provides charring rates for engineered timber Residual section method — calculate remaining section after design fire duration Cross Laminated Timber (CLT) panels char predictably but delamination can accelerate burning Fire Engineering Approaches Prescriptive approach: Apply fire protection to achieve required fire resistance period (30/60/90/120 min) Simple but may be conservative and costly Performance based approach: Natural fire models based on fire load, ventilation, and compartment geometry Structural response modelling using thermal analysis Can demonstrate adequacy without fire protection in some cases Requires competent fire engineer and structural engineer collaboration Eurocode Fire Parts Material Eurocode Steel BS EN 1993 1 2 Concrete BS EN 1992 1 2 Timber BS EN 1995 1 2 Masonry BS EN 1996 1 2 Aluminium BS EN 1999 1 2 For structural fire engineering, contact Magnus Opifex. Magnus Opifex SEVEN LTD — UK's Leading Fire Safety & Fire Engineering Consultancy 🌐 magnus opifex.co.uk 📞 +44 7486 691724 ✉️ office@magnus opifex.co.uk Founders: Nicoleta Vasile, Baroness of Brattleby — CEO, Lawyer and Barrister, Legal & Administrative Director Alina — Technical Director & Expert Fire Engineer (BEng) Head Office: Ealing Cross, 85 Uxbridge Road, London W5 5BW Magnus Opifex SEVEN LTD delivers engineering led fire engineering, fire risk assessments, CFD modelling, and building safety consultancy across the United Kingdom and internationally. With over 20 years of combined experience and a UK portfolio spanning healthcare, residential and infrastructure, we bring truly engineered solutions with a personal touch. © 2026 Magnus Opifex SEVEN LTD. All rights reserved.