BS EN 13501-2BS 476-22Approved Document BScottish Technical Handbook Section 2Building Bulletin 100 (BB100)Reviewed 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 / BS 476-22).
Precision Specification
Composite Architectural Glass Assembly
Multi-Ply Safety Specification
Accessible Static View
Schematic exploded horizontal cross-section showing sequential structural placement.
01
Outer Structural Ply(Thermally Toughened Glass)
10.0mmExternal impact and wind barrier
02
Engineered Interlayer Core(Structural SentryGlas / Acoustic PVB)
1.52mmViscoelastic damping & residual load support
03
Inner Structural Ply(Thermally Toughened Glass)
10.0mmInterior barrier and post-breakage integrity
BS EN 12150 / BS EN 14449 Architectural ReferenceIllustrative diagram — project structural verification required
Physical & Mechanical Performance Characteristics
Safety Class:Class 1B1 or 1C1 (BS EN 12600) on approved fire-rated variants
Bending Strength:High integrity under thermal shock during fire conditions up to 1000°C furnace test curves (ISO 834 / EN 1363-1)
Thermal Shock Resistance:Designed to withstand standard EN 1363-1 ISO fire heating curve (reaches 842°C at 30 min, 945°C at 60 min)
Fracture Behaviour:Intumescent core holds assembly intact and creates an expanding 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 argon-filled IGU
Acoustic Reduction (Rw):Rw 38 dB to Rw 47 dB (thick multi-ply intumescent gel layers provide exceptional acoustic attenuation)
Max Sheet Dimension:Restricted strictly by independent fire test scope reports (e.g. 1500mm × 3000mm in certified steel frames)
Density & Mass:Substantially heavier: ~2.5 kg/m²/mm glass + ~1.4 kg/m² per mm intumescent gel (e.g. EI60 25mm ≈ 55–60 kg/m²)
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 (preventing spontaneous ignition of clothing/materials)
- •Dual compliance: delivers both life safety fire barrier and certified human impact safety (BS EN 12600 Class 1B1)
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
Dimensional Tolerance:Panes <= 2000mm: ±2.0mm; panes > 2000mm: ±3.0mm; thickness tolerance ±1.5mm
Thickness Tolerance:EI30: 14–18mm ± 1.5mm; EI60: 23–28mm ± 2.0mm
Flatness & Roller Wave:Overall bow max 2.5mm/m
Hole & Cutout Geometry Rules:Holes and cutouts strictly prohibited unless explicitly validated in the manufacturer’s primary test certification report
Most intumescent fire glasses must be cut only by licensed processing centers with certified edge-tape sealing equipment.
Structural Design Basis (Eurocodes / BS EN 16612)CEN / BSI Harmonised
Characteristic Strength:Constituent glass plies meet standard float or toughened criteria; structural load-bearing capacity under fire governed by test assessment
Elastic Modulus (E):70,000 MPa (glass plies)
Poisson's Ratio (ν):0.22
Linear Expansion (α):9.0 × 10⁻⁶ K⁻¹
Design Bending Stress Formula (BS EN 16612):Mechanical dead-load and wind-load verified per EN 16612; fire barrier capacity strictly empirical per EN 1363-1 test reports
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.
4Verify permanent indelible fire kitemark is visible after framing beads are fitted.
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