The drive to improve EPC ratings is leading to retrofit insulation that can introduce serious fire safety risks. Building owners must understand the dangers.. The Retrofit Rush Government targets to achieve EPC Band C by 2035 for rented properties are driving a wave of retrofit insulation installations. Many of these are being carried out without adequate consideration of fire safety. The Risks External Wall Insulation (EWI): Expanded polystyrene (EPS) — combustible and contributes to fire spread Phenolic foam — better fire performance but still combustible Mineral wool — non combustible but more expensive Cladding systems over insulation may not meet current combustibility requirements Internal Wall Insulation (IWI): Reduces room sizes and can trap moisture May compromise compartmentation if not properly fire stopped Introduces additional fire load within the building envelope Cavity Wall Insulation: Retrofit cavity insulation can create paths for fire spread between floors Cavity barriers may be bridged or displaced during installation Particularly dangerous in timber frame properties with combustible cavities Post Grenfell Regulatory Context The Building Safety Act and amendments to Building Regulations now: Ban combustible materials above 18m (Regulation 7) Require consideration of whole wall system performance (not just individual component testing) Mandate PAS 9980 risk appraisal for existing external walls Best Practice for Retrofit 1. Commission fire engineering advice before specifying insulation systems 2. Use non combustible insulation wherever possible (mineral wool, PIR with appropriate fire stops) 3. Maintain cavity barriers — ensure existing barriers are not bridged or damaged 4. Update fire risk assessment after any insulation works 5. Consider whole building fire strategy — not just the element being insulated 6. Ensure competent installation — third party certified installers preferred Case Studies Several serious fires have been linked to retrofit insulation: Combustible EWI contributing to rapid external fire spread Cavity wall insulation allowing fire to bypass compartment walls Internal insulation creating concealed fire spread paths For retrofit fire safety guidance, contact us. 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.