When selecting the right fire-resisting door or wall system, you will often encounter the terms ‘EW’ and ‘EI’.
These classifications are defined in BS EN 13501-2, which is recognised under the UK Building Regulations as the standard method for classifying fire resistance.
But what do EW and EI actually mean?
And why does understanding the difference matter when specifying fire protection for your project?
The basics: E, W and I explained
Fire resistance is tested in three main performance criteria:
E – Integrity
The element must prevent the passage of flames, hot gases, and smoke to the non-fire side.
It ensures that the fire does not spread through openings or cracks during the test period.
W – Radiation
The element limits the transfer of radiant heat to the non-exposed side to a safe level,
reducing the risk of ignition of nearby materials or objects.
I – Insulation
The temperature on the non-fire-exposed side must not exceed specified limits,
ensuring that heat transfer is restricted and that adjacent areas remain safe for evacuation.
What does EW mean?
A construction element with an EW classification has been tested for integrity (E) and radiation control (W), but not for thermal insulation (I).
In practice, this means that the element prevents flames and hot gases from passing through and limits the amount of radiant heat transferred to the non-fire side — but the surface temperature on that side can still rise significantly during a fire.
EW-rated doors or partitions are typically used in areas where people do not remain for long periods, such as storage rooms, technical spaces, or service areas.
They provide adequate fire containment at a lower cost compared to EI-rated constructions, but offer less protection for evacuation routes or occupied spaces.
What does EI mean?
A construction element with an EI classification has been tested for both integrity (E) and insulation (I).
This means it not only prevents flames and hot gases from passing through, but also limits the temperature rise on the non-fire side to a safe level.
EI-rated doors and partitions therefore provide a higher level of protection, especially in areas where people may need to evacuate or remain in place during a fire — such as corridors, stair enclosures, or occupied rooms.
Common classifications include:
- EI 30 – 30 minutes integrity and insulation
- EI 60 – 60 minutes
- EI 90 and EI 120 – for higher-risk applications such as industrial facilities, car parks, or storage compartments
These performance ratings are determined through testing in accordance with BS 476-22 or BS EN 1634-1, and classified under BS EN 13501-2.
Applications of EW and EI classifications
| Situation | Recommended classification |
| Service or plant room (no regular occupancy) | EW |
| Escape route, corridor or public area | EI 30 or higher |
| Industrial hall or compartment separating different functions | EI 60 – EI 120 |
These recommendations ensure the right balance between cost, functionality, and safety.
EW constructions provide basic containment where no people are present, while EI constructions offer full protection of integrity and insulation — essential for safe evacuation and occupied spaces.
Smart alternative: Compact door + fire curtain (up to EI 120)
For larger openings where a fire-resistance requirement applies, many suppliers immediately think of a fire-rated overhead door. However, such doors are often expensive, less suitable for daily use, and limited in design flexibility.
Rolflex offers a smart alternative:
a Compact door for everyday use — aesthetically integrated and space-saving — combined with a certified fire curtain on the opposite side of the wall.
The fire curtain provides:
- Fire resistance up to EI 120, even for larger openings
- Full certification to BS EN 1634-1 and classification under BS EN 13501-2
- No compromise on ease of operation or design quality
This combination allows you to enjoy a visually refined, practical solution for day-to-day operation while maintaining a high level of fire protection — often at a lower overall cost.
Conclusion
Fire safety is not only about whether a door is “fire-resisting,” but how it protects.
The difference between EW and EI classifications is fundamental.
By understanding what these ratings mean — and by considering innovative alternatives such as the Compact door combined with a fire curtain — you can make better-informed choices that enhance both building safety and user convenience.