What is EI60?
EI60 is a fire resistance classification meaning the glazing system maintains both Integrity (E) and Insulation (I) for 60 minutes when exposed to fire on one side.
- Integrity (E): The glass and seals prevent flames and hot gases from passing through to the non-fire side for the full 60 minutes.
- Insulation (I): The temperature on the non-fire (safe) side does not exceed an average rise of 140K, or a maximum of 180K at any point, for 60 minutes.
EI60 is the most commonly specified fire resistance rating for escape routes, stairwells, and compartment boundaries in commercial and residential buildings across Europe, Australia and the UK.
E, EW and EI ?What's the Difference?
| Rating | Integrity | Radiation | Insulation | Typical Use |
|---|---|---|---|---|
| E | Yes | No limit | No limit | Smoke barriers, external walls |
| EW | Yes | Limited | No limit | Atriums, large open spaces |
| EI | Yes | Controlled | Yes (140K avg / 180K max) | Escape routes, stairwells, hospitals |
How EI60 Works
EI60 fire-rated glass is not a single pane. It is a carefully engineered multi-layer assembly that reacts to heat in a controlled way:
Outer Toughened Glass
Provides structural strength and impact resistance. First line of defence against thermal shock.
Intumescent Interlayer
Expands when heated above ~120°C, forming a thick opaque foam barrier that blocks heat transfer and seals cracks.
Fire-Resistant Glass Core
Borosilicate or special soda-lime glass with low thermal expansion. Maintains shape under extreme heat.
Secondary Intumescent Layer
Additional heat-absorbing and sealing layer for extended performance in EI60 and EI90 systems.
Inner Toughened Glass
Protects the fire-resistant core during normal use and provides the inner face of the glazing unit.
When exposed to fire, the outer toughened glass may crack, but the intumescent layers expand to fill gaps and form an insulating char. The fire-resistant core remains intact, and the inner glass stays below the critical temperature threshold for 60 minutes.
Applications
EI60 glazing is specified wherever people need protected escape paths or where fire compartments must be separated while maintaining visibility:
Stairwell Enclosures
EI60 is the default rating for fire-isolated stairways in most building codes. It protects evacuees from radiant heat while allowing natural light into the stair core.
Corridor Partitions
Fire-rated corridor glazing separates escape routes from fire compartments. EI60 provides the insulation needed for occupants to pass safely.
Elevator Lobbies
Lift lobbies often require EI60-rated glazing to protect the lobby as a temporary refuge area during evacuation.
Hospital ICUs & Wards
Healthcare facilities specify EI60 for patient visibility, natural light and fire compartmentation where bed-bound patients cannot self-evacuate.
School Evacuation Routes
Schools use EI60 glazing in corridors and stairwells to create bright, visible escape paths while meeting Department of Education fire safety requirements.
Commercial Atriums
Multi-storey atriums often require EI60-rated glass walls to separate the atrium void from adjacent occupancies.
Standards & Testing
EI60 is recognised across multiple standards, but the test method and certification requirements differ by jurisdiction:
| Standard | Region | Equivalent Rating | Test Laboratory |
|---|---|---|---|
| AS1530.4 | Australia | -/60/30 or -/60/60 | CSIRO, NATA-accredited |
| BS476-22 | UK / Commonwealth | EI60 | Warringtonfire, UKAS-accredited |
| EN1364-1 / EN1634-1 | Europe | EI60 | Notified Body (CE/UKCA) |
| UL9 / NFPA 257 | USA / Canada | 60 min (Hose Stream) | UL, Intertek |
Important: a test report under one standard is not automatically accepted under another. Always verify with your local building certifier which standard and laboratory accreditation are required for your project.
Sizing & Limitations
EI60 performance is system-specific. The maximum panel size depends on the glass composition, frame type and intumescent seal configuration tested together:
| System Type | Typical Max Width | Typical Max Height | Frame Requirement |
|---|---|---|---|
| Steel-framed EI60 | 3.0 m | 3.5 m | Min. 1.5 mm galvanised steel |
| Aluminium-framed EI60 | 1.8 m | 2.4 m | Thermally broken, fire-rated profile |
| Timber-framed EI60 | 1.2 m | 2.1 m | Hardwood or fire-treated softwood |
| Door vision panel EI60 | 0.9 m | 1.5 m | Matched steel or timber door frame |
Seal & Glazing Materials
- Intumescent seals: Must be graphite or sodium silicate-based, rated for the same duration as the glass.
- Setting blocks: Non-combustible fibre or ceramic, not PVC or rubber.
- Perimeter sealant: Fire-rated silicone or intumescent mastic; standard neutral-cure silicone will fail.
- Fixings: Steel screws or anchors at spacing per the test report. Aluminium fixings may melt.
Frequently Asked Questions
What is the difference between EI60 and E60?
E60 means 60 minutes of integrity only ?flames are blocked, but heat is not. EI60 means 60 minutes of both integrity and insulation ?the safe-side temperature stays below the critical threshold. Most building codes for escape routes require EI, not just E.
Can EI60 glass be used in external facades?
Yes, but only if the specific system has been tested for external exposure including wind load, thermal cycling and water penetration. External EI60 systems are available, but they are a separate product line from internal partition glazing. Always request the external-use test report.
What frame material is required for EI60?
Steel is the most common and allows the largest panel sizes. Fire-rated aluminium and timber frames are available but with smaller maximum dimensions and stricter installation requirements. The frame must be part of the same tested system as the glass.
Does EI60 glass provide acoustic insulation?
Standard EI60 glass has moderate acoustic performance (Rw 32?6 dB). For higher acoustic ratings, laminated EI60 glass or double-glazed EI60 units are available. These must be tested and certified as complete systems ?do not assume acoustic laminates can be added to a standard EI60 product.
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