EI 120 fire rating is a 120-minute fire-resistance classification where a construction maintains integrity (E) and insulation (I) for two hours. Integrity prevents flames/smoke passing through; insulation limits the temperature rise on the unexposed face, protecting occupants and adjacent materials throughout the duration. Compared with EI 60 or EI 90, EI 120 places the most demanding requirements on glazing, profiles, seals, hardware and junctions – and on installation control.
At a glance
Note: Maintaining low safe-side surface temperatures also reduces radiant heat, improving conditions for nearby occupants and finishes.
EI vs EW vs E - what’s the difference? | |||
|---|---|---|---|
| Property / Class | E (Integrity) | EW (Integrity + Radiation) | EI (Integrity + Insulation) |
| Stops flames/smoke passing | |||
| Limits radiant heat near the element | |||
| Limits temperature rise on unexposed face | |||
| Typical glazing make-up | Integrity fire glass | Radiation-control glass | Insulating fire glass (multi-laminate/intumescent) |
| Typical use cases | Low-proximity zones | Radiation control where EI not required | Close-proximity, routes, protected spaces, sensitive occupancies |
1) Use a tested, documented assembly
Follow the exact combination of profiles/reinforcements, glazing, beads, seals, intumescent components, fixings, substrates and hardware stated in the classification report.
2) Glass type
Specify EI-rated insulating fire glass compatible with the system. These are typically multi-laminate/intumescent constructions with defined thickness, edge cover and weight. Do not substitute EW or E glass.
3) Sizes & limits
Respect pane/leaf maximums, aspect ratios, visible edge cover, mullion/transom centres and profile spans from the evidence. Oversizing requires a formal EXAP/assessment.
4) Glazing details
5) Hardware & accessories
Only use listed hinges, locks, closers, panic hardware, drop seals and any electromagnetic hold-open devices referenced in evidence. For 120 minutes, check closer power, bearing capacity, and any required thermal protection kits for ironmongery.
6) Interfaces & substrates
Install into the tested substrate (e.g., concrete, lined stud). Match perimeter firestopping density/depth, and document movement joints and deflection criteria.
7) Identification & maintenance
Apply ID labels, include DoP, installation and O&M manuals, and plan inspections (glass edges, seals, ironmongery). Two-hour EI assemblies benefit from documented maintenance intervals.
EI 120 fire rating is achievable in aluminium systems when the tested build-up is followed precisely.
Scope: Commonly fixed lights; openable EI-rated windows are uncommon and must be explicitly tested with their exact opening hardware and seals.
Glazing: Use the tested EI glass (type/thickness) and maintain edge cover and intumescent liners as specified.
Locations: Internal partitions to protected routes; external/boundary applications where the strategy demands 120-minute insulation.
Spec tips: Confirm pane maximums, permitted mullion/transom types, head/sole details; coordinate ventilation via AOVs or separate systems.
Leaf types: Single/double leaves, with/without overpanels/side-lights – each configuration must be covered by evidence.
Hardware: Only listed hinges, locks, closers, panic devices, drop seals. If hold-open is needed, use an automatic release linked to the fire alarm.
Additional performance: Smoke control (Sa/Sm) is separate to EI; include if required.
Spec tips: Check clearances, closer power, glazing bead type, ironmongery packers, and any kick/guard plates. For 120 minutes, confirm any intumescent kits for hardware are included where evidence requires them.
Layout: Keep to tested post spacing, deflection limits, and head-of-wall junctions. Unframed/butt-jointed glass is typically not permitted for EI unless specifically tested.
Interfaces: Use only approved firestopping and tested substrates; document movement joints.
People proximity: EI is preferred where occupants or combustibles may be close to the safe face for prolonged periods.
Spec tips: For door-integrated screens or full-height runs, ensure the combined assembly (door + side-light + overpanel) is within scope.
Build exactly to the documented configuration. If your intended size, hardware, glass or junction isn’t covered, obtain EXAP/assessment before proceeding.
What does EI 120 fire rating mean?
The element maintains integrity and insulation for 120 minutes: no through-flames, and the safe-side temperature rise is limited (ΔTavg ≤ 140 °C; ΔTmax ≤ 180 °C).
When should I choose EI 120 over EI 90 or EW 120?
Choose EI 120 when the fire strategy requires two hours of insulation – e.g., higher-risk compartments, tall/complex buildings, or where people/combustibles remain close to the glazing.
Does EI 120 fire rating include smoke control?
No. Smoke control (Sa/Sm) is a separate classification and must be specified and evidenced independently.
Can I mix EI doors with EW screens in one elevation?
Only if the combined assembly (door + screen + overpanel) is covered by evidence. Otherwise keep the elevation to EI or obtain an assessment.
What glass types achieve EI 120 fire rating?
Insulating fire glass (multi-laminate/intumescent) matched to the aluminium system, with specific thickness, weight and edge cover per the classification report.
Can I oversize panes or change ironmongery?
Not without formal EXAP/assessment. Stick to tested sizes, hardware and construction to retain the EI 120 classification.
For more information on our fire rated windows and products please visit our Fire Rated Aluminium Windows
For more information on our fire rated doors and products please visit our Fire Rated Aluminium Doors
For more information on our fire rated partitions and products please visit our Fire Rated Glass Partitions