BS EN 13501-2BS 476-22Approved Document B (Fire Safety)Scottish Technical Handbook Section 2Reviewed Technical Specification
Fire-Resistant Glazing Systems
Certified intumescent barrier assemblies engineered for Integrity (E), Radiation Control (EW), and Thermal Insulation (EI).
Engineering Definition: Specialist glass constructions incorporating clear intumescent interlayers that react at approximately 120°C, transforming into an opaque, rigid heat-shielding foam that prevents the spread of flames, smoke, and conductive heat transfer (BS EN 13501-2).
Material Construction Matrix
EI60 Multi-Ply Intumescent Fire-Resistant Glazing
Thermal Transmittance:3.4 W/m²K
Acoustic Reduction:Rw 44 dB
Explode Layers
1
Exposed Outer Float Ply(4mm Annealed Float)
4.0mm
2
Primary Intumescent Gel Core(Hydrated Sodium Silicate Gel)
3.0mm
3
Intermediate Glass Ply(4mm Float Core)
4.0mm
4
Secondary Intumescent Core(Hydrated Silicate Intumescent)
3.0mm
5
Unexposed Face Glass Ply(4mm Float)
4.0mm
Physical & Mechanical Performance Characteristics
Safety Class:Class 1B1 or 1C1 (BS EN 12600) on approved variants
Bending Strength:High integrity under thermal shock during fire conditions up to 1000°C furnace test curves
Thermal Shock Resistance:Designed to withstand standard EN 1363-1 ISO fire heating curve
Fracture Behaviour:Intumescent core holds assembly intact and creates insulating heat shield
Typical U-Value (Ug):2.8 to 4.5 W/m²K monolithic; down to 1.1 W/m²K when combined into an IGU
Acoustic Reduction (Rw):Rw 38 dB to Rw 47 dB (thick multi-ply intumescent layers provide exceptional acoustic attenuation)
Max Sheet Dimension:Restricted strictly by independent test certification fire scope reports (e.g. 1500mm × 3000mm)
Density & Mass:Substantially heavier: ~2.5 kg/m²/mm glass + ~1.4 kg/m² per mm intumescent gel
Key Architectural Advantages
- •Life safety containment: prevents flashover and radiant heat ignition along protected escape routes and fire stairwells
- •EI class ensures surface temperature on unexposed face does not exceed 140°C mean rise above ambient
- •Dual compliance: delivers both life safety fire barrier and certified impact safety (BS EN 12600)
Critical Engineering Constraints
- •CRITICAL: Glass cannot be installed into non-certified frames. Fire test certificate covers the ENTIRE SYSTEM ONLY (glass, frame, intumescent seals, fixings)
- •Intumescent layers are sensitive to UV exposure and edge moisture; units for external use require integrated UV-absorbing PVB plies
- •Substantial dead weight requires structural reinforcement of timber, steel, or aluminium fire-rated frames and floor slabs
Fabrication & Edge Processing Tolerances
Cut After Toughening:PROHIBITED (Catastrophic Fracture)
Heat Soak Testing (HST):Not Required
Most intumescent fire glasses must be cut only by licensed processing centers with certified edge-tape sealing equipment.
Architectural Specifier Checklist
Verify these technical criteria prior to contract documentation:
1Verify required classification: E (Integrity only), EW (Integrity + Radiation reduction <15 kW/m²), or EI (Integrity + Full Thermal Insulation).
2Demand supplier field of application test report (Certifire / Warringtonfire) matching exact proposed dimensions and orientation.
3Do NOT substitute standard toughened glass for fire-resistant glass; standard toughened shatters within 3 to 5 minutes in a fire.
Frequent Commercial Applications
Network Procurement Routing
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Recommended Action: Consult certified fire door and architectural fire screen specialist contractors with third-party test evidence.
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Last Standard Verification: 2026-10-30