Almost every fire-resistant product carries a code: EI 30, EI 60, EW 30, R 120. They help determine whether a product is suitable for your situation, yet they are often misread. In this article you will learn how the classifications are structured and how to establish which performance you need.
The letters
The classification follows from the European standard NEN-EN 13501-2 and consists of letters describing the performance, followed by a number in minutes.
| Letter | Stands for | What it means |
|---|---|---|
| R | Résistance (load-bearing capacity) | The structure keeps bearing load. Applies to load-bearing elements: columns, beams, floors. |
| E | Étanchéité (integrity) | No flames or hot gases pass through. |
| I | Isolation (thermal insulation) | The temperature rise on the unexposed side stays within the test limits: no more than 140 °C on average and no more than 180 °C at any measuring point. |
| W | Radiation | The heat radiation on the unexposed side stays below a limit value. A lighter requirement than I. |
| S | Smoke (smoke leakage) | Limited smoke leakage: Sa at ambient temperature, S200 also at 200 °C. |
The number is the time in minutes for which all the criteria listed are met in the test. EI 60 therefore means: sixty minutes of both integrity and thermal insulation, under the test conditions of the standard.
EI versus EW
EI limits the temperature rise on the unexposed side. EW instead limits the heat radiation passing through and is therefore a lighter requirement. Both are test criteria. They do not tell you at what distance someone can safely stand next to the construction in a real fire.
EW products, mostly fire-resistant glass, are often cheaper but not permitted everywhere. Which criterion a component must meet follows from the requirement on the separation and the assessment criteria that go with it. That is not a choice you make on price.
Which performance is required?
The Bbl (Dutch Buildings Decree) does not set requirements in the form of EI classes. It sets requirements for the WBDBO: the resistance to fire penetration and fire spread between spaces, determined in accordance with NEN 6068. The classification of a wall, door or seal is a building block in that determination, not a substitute for it.
Some starting points for new construction:
| Situation | Starting point for new construction |
|---|---|
| Between two fire compartments | A WBDBO of at least 60 minutes. The Bbl contains 30-minute exceptions, for example for a residential function whose permanent fire load does not exceed 500 MJ/m² and in which no floor of an occupied area is higher than 7 metres. |
| Towards an adjacent plot | Assessed using an imaginary mirrored building on the other side of the plot boundary. The outcome depends on the requirement, the façade and the distance; there is no fixed value per building. |
| Load-bearing structure | A requirement for fire resistance with regard to collapse, depending on the use, height and fire load, among other things. |
Different levels and rules apply to existing buildings and renovations. Which requirement applies to your separation follows from the Bbl, the approved drawings and the building's fire safety concept.
Note the notation EI₁ and EI₂ for doors: the subscript refers to where the temperature on the unexposed side was measured. EI₁ is the stricter variant.
May a door have a lower classification than the wall?
Not because the door takes up a small part of the wall. The WBDBO is not an average of wall and door weighted by area. NEN 6068 looks at all possible fire spread routes, and the route with the lowest resistance is decisive. Since the amendment NEN 6068 + A1:2024, the standard also says so explicitly. A 30-minute door in a direct separation that requires 60 minutes therefore does not comply.
Yet you will also find 30-minute doors in buildings with 60-minute requirements. That can be correct, for example if:
- a 30-minute requirement applies to that specific separation;
- it is an existing building to which a different level applies.
So whether a door complies follows from the requirement for that separation, the assessment criteria and a documented design or a WBDBO calculation that covers all relevant fire spread routes. In doubt? Have the route assessed before you accept or order a door.
The pitfall: a classification applies within its field of application
A classification belongs to a complete system, not to a single product. Fire-resistant glass with EI 60 achieves that value in the frame system, with the glazing gaskets and hardware with which it was tested and classified. The same pane in a different frame is not classified without substantiation, even if the glass is identical. The same applies to seals: the system was tested in a particular wall or floor, with a particular build-up.
Not every variant has to be tested separately. Standards have a direct field of application and rules for the substantiated extension of test results. But the installation must fall within that substantiated scope.
This is a common reason for rejection during inspections: on paper the product is right, but the application falls outside the field of application.
Not sure which performance applies to your building? An inventory maps the required and the actual value for each separation. Also read the explanation of the WBDBO requirement.
Frequently asked questions
Thirty minutes of integrity (E) and thermal insulation (I) in the fire test: no flames or hot gases get through, and the temperature on the unexposed side rises by no more than 140 °C on average and by no more than 180 °C at any point. EI 60 is the same for sixty minutes.
EI limits the temperature rise on the unexposed side; EW only limits the heat radiation passing through. EW is therefore a lighter requirement and often cheaper, but not permitted everywhere. Which criterion is needed follows from the requirement and the assessment criteria for that separation.
Not because the door has a smaller surface area. Under NEN 6068, the fire spread route with the lowest resistance is decisive. A 30-minute door can only comply if the requirement for that separation allows it. That must follow from the requirement, the design or a WBDBO calculation that covers all relevant fire spread routes.
No, to the complete system within the classification's field of application. Fire-resistant glass achieves its classification in the frame system with which it was tested. In a different frame, that classification is not valid without substantiation, even with identical glass.
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