For many clients, fire-resistant glass is the way to achieve compartmentalization without a closed wall: light and sightlines are preserved, while the separation still meets the required WBDBO. But fire-resistant glass is not a standalone product - it is a system of glass, frame, hardware and seals, tested and classified as a whole. This article explains what the classifications mean, where glass is used and what determines the cost.
E, EW and EI: what is the difference?
Just as with penetrations and doors, fire-resistant glass is classified according to NEN-EN 13501-2. The letters stand for separate performances in the fire test: E (integrity - no passage of flames or hot gases), W (heat radiation on the unexposed side stays below a limit value) and I (thermal insulation - the temperature rise on the unexposed side stays within the test limits). The number is the duration in minutes.
| Classification | Meaning | Typical application |
|---|---|---|
| E 30 / E 60 | Integrity only: stops flames and hot gases, but does not limit heat radiation or temperature on the unexposed side. | Situations in which the requirement and assessment criteria only call for integrity. |
| EW 30 / EW 60 | Integrity and limited heat radiation; the temperature is not limited as with I. | Applications in which the requirement allows EW. |
| EI 30 | 30 minutes of integrity and thermal insulation. | For example office partitions, doors with glazed panels, corridor walls. |
| EI 60 | 60 minutes of integrity and thermal insulation. | For example separations with a stricter requirement, stairwells. |
Which classification is needed follows from the requirement for the separation and the associated assessment criteria, not from a rule of thumb. EI limits the temperature rise in the test, but that is no guarantee that someone can safely remain right next to the glass during a real fire.
Smoke resistance is a separate performance. An E, EW or EI classification does not automatically demonstrate that a requirement for resistance to smoke passage is met; that is determined in accordance with NEN 6075.
The frame counts toward the classification
This is the most common mistake with fire-resistant glass: the classification applies to the tested combination of glass, frame profile, glazing system and hardware, within the permitted dimensions and fixing details of the classification. The same glass in a different frame - or an original frame with a different type of gasket or setting blocks after replacement - is no longer automatically EI 30 or EI 60. When renovating existing fire-resistant screens, this is a recurring problem: the glass looks intact, but if the frame system no longer falls within the classification's field of application, the performance can no longer be demonstrated.
Where is fire-resistant glass applied?
- Stairwells and escape routes, where a closed wall would limit orientation and daylight too much.
- Office partitions between units or between corridor and office space in multi-tenant real estate, where transparency is desired.
- High-rise, in shared spaces where daylight is the primary architectural requirement alongside compartmentalization.
- Education and healthcare, in walls between corridors and classrooms or treatment rooms, for visibility without compromising fire safety.
What determines the cost?
Fire-resistant glass is priced per m2 and depends heavily on the classification (for example EI 30 or EI 60), the dimensions of the panes and whether the existing frame can be reused or must be replaced. Large, divisible panes in standard sizes are cheaper than custom work on site with non-standard dimensions. Because glass and frame are quoted together, you receive one price including glazing, frame and installation - with no separate items that only become clear afterwards.
Not sure whether your existing fire-resistant glazing still demonstrably meets its classification? Request an inspection, or first try the free quickscan.
Frequently asked questions
E glass stops flames and hot gases, but does not limit heat radiation or temperature on the unexposed side. EW additionally limits heat radiation, EI the temperature rise. Which class is needed follows from the requirement for the separation and the assessment criteria. Smoke resistance is a separate performance.
Only if that combination of glass and frame falls within the classification's field of application. A different frame profile, different hardware or different glazing gaskets can invalidate the classification, even if the glass itself is original EI glass.
Not automatically. Those properties must be specified and tested separately; include them in the brief in advance if you need them.
Want to know more about fire-resistant glass?
Fire-resistant glass made to measure: glazed partitions, screens and glazing with EI 30 or EI 60 classification, supplied and installed.
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