BS EN 12150-1BS EN 12600 (Class 1C1)Approved Document KBS EN 14179 (Heat Soaked)Reviewed Technical Specification

Toughened Safety Glass (Tempered)

Thermal pre-stressing engineered for high impact resistance, wind-load capacity, and diced safety fracture.

Engineering Definition: Monolithic float glass subjected to controlled heating to approximately 620°C followed by rapid forced-air quenching, inducing balanced compressive stresses (>= 69 to 100+ MPa) on exterior surfaces and tensile stress within the core (BS EN 12150-1).

Precision Specification

Composite Architectural Glass Assembly

Multi-Ply Safety Specification

Accessible Static View

Schematic exploded horizontal cross-section showing sequential structural placement.

Outer Structural Ply(Thermally Toughened Glass)

10.0mmExternal impact and wind barrier

Engineered Interlayer Core(Structural SentryGlas / Acoustic PVB)

1.52mmViscoelastic damping & residual load support

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 1C1 (BS EN 12600: drop height 1200mm)

Bending Strength:Characteristic tensile bending strength fb,k = 120 N/mm² (float base) / 90 N/mm² (patterned base) vs 45 N/mm² annealed float

Thermal Shock Resistance:Withstands temperature differentials up to 200°C (vs ~40°C for annealed float)

Fracture Behaviour:Disintegrates into small, relatively blunt granular dice (minimum 40 particles per 50mm × 50mm square per EN 12150-1), drastically reducing laceration risk

Typical U-Value (Ug):5.7 to 5.8 W/m²K (monolithic vertical, EN 673) — requires IGU assembly with Low-E coating for thermal compliance

Acoustic Reduction (Rw):Rw 29 (-2; -3) dB (4mm) to Rw 35 (-1; -2) dB (12mm) — exhibits marked coincidence dip at critical frequencies

Max Sheet Dimension:Up to 3210mm × 6000mm (jumbo line capacity dependent; oversize up to 3300mm × 9000mm on specialist furnaces)

Density & Mass:2.50 kg/m² per 1mm nominal thickness (density 2500 kg/m³ per BS EN 572-1)

Key Architectural Advantages

•High resistance to dynamic human impact and lateral wind loads (4–5× higher mechanical capacity than annealed float)
•High thermal endurance preventing thermal fracture from solar radiation hotspots, shadow lines, or proximity to radiators/heaters
•Compliant safety glazing classification (Class 1C1) for commercial doors, side panels, and low-level glazing to Approved Document K

Critical Engineering Constraints

•CANNOT be cut, drilled, notched, or edged after thermal toughening — all fabrication must precede furnace heating
•Susceptible to nickel sulphide (NiS) spontaneous inclusion fracture unless heat soak tested (HST) to BS EN 14179
•Zero post-breakage containment when fractured alone (requires lamination for barrier, balustrade, or overhead applications)

Fabrication & Edge Processing Tolerances

Cut After Toughening:PROHIBITED (Catastrophic Fracture)

Heat Soak Testing (HST):Recommended to BS EN 14179

Dimensional Tolerance:Panes <= 2000mm: ±1.5mm; panes 2000–3000mm: ±2.0mm; panes > 3000mm: ±3.0mm (BS EN 12150-1 Table 2)

Thickness Tolerance:4–6mm: ±0.2mm; 8–12mm: ±0.3mm; 15mm: ±0.5mm; 19mm: ±1.0mm

Flatness & Roller Wave:Overall bow max 3.0mm/m (0.3%); roller wave max 0.3mm/300mm (high-spec architectural facades: 0.15mm/300mm); edge lift <= 0.4mm

Hole & Cutout Geometry Rules:Diameter D >= nominal thickness t; Edge-to-hole clearance >= 2t; Inter-hole clearance >= 2t; Corner distance >= 6t; Internal corner cutout radius r >= t (min 6mm)

All hole centers must be positioned at least 2× glass thickness from glass edges and 6× thickness from corners to prevent furnace stress cracking.

Structural Design Basis (Eurocodes / BS EN 16612)CEN / BSI Harmonised

Characteristic Strength:fb,k = 120 N/mm² (BS EN 12150-1)

Elastic Modulus (E):70,000 MPa (70 GPa per BS EN 572-1)

Poisson's Ratio (ν):0.22 (BS EN 572-1)

Linear Expansion (α):9.0 × 10⁻⁶ K⁻¹ (BS EN 572-1)

Design Bending Stress Formula (BS EN 16612):fg,d = [kmod · ksp · fg,k] / gamma_M;A + [kv · (fb,k - fg,k)] / gamma_M;v (BS EN 16612: gamma_M;v = 1.2, kmod = 0.74 short-term wind)

Architectural Specifier Checklist

Verify these technical criteria prior to contract documentation:

1Confirm all notch, hole, and edge details prior to sign-off (post-toughening modification causes catastrophic shatter).

2Specify Heat Soak Testing (HST to BS EN 14179) for all structural, overhead, or high-level facade installations to mitigate NiS inclusion risk.

3Check visible safety kitemark positioning against framing rebate depth so compliance remains verifiable post-installation.

4Confirm roller wave orientation (horizontal furnace rollers should run parallel to building horizontal transom lines to minimize optical distortion).

Frequent Commercial Applications

Frameless Glass Doors & Entrances

Commercial patch-fitted doors with countersunk hinge cut-outs.

Internal Frameless Partitions

Dry-jointed 10mm or 12mm office dividing walls.

Balustrades (Infill Panels)

Fully framed four-edge clamped safety panels.

Network Procurement Routing

BuyGlass.co

Commercial cut-to-size glass manufacturing, direct supply, and transactional quoting platform.

Recommended Action: Direct supply specification for cut-to-size toughened panels or local glazier installation quotes.

Proceed to BuyGlass.co

Reviewed by: Chartered Facade Engineer, BuyGlass Technical Editorial Panel

Last Standard Verification: 2026-10-30