Resistance to fire and reaction to fire
Two distinct notions, regularly confused, which do not bear on the same thing. Fire resistance and reaction to fire do not measure the same thing.
Resistance to fire is the ability of a construction element to continue performing its function during a fire. It concerns works: walls, floors, doors, ducts.
Reaction to fire is the behaviour of a material towards fire, that is its contribution to the development of the fire. It concerns products.
A wall has a resistance to fire. A finish has a reaction to fire. Confusing the two leads to specifying a product that does not meet the requirement.
The structure of a resistance notation
The notation combines letters, indicating the functions maintained, and a number, indicating the duration in minutes. Each letter corresponds to a defined function.
Three principal letters.
R for loadbearing capacity, the ability to carry loads.
E for integrity, the ability to prevent the passage of flames and hot gases.
I for insulation, the ability to limit heat transmission.
The number expresses a duration in minutes during which the designated functions are maintained.
The letters combine according to the function of the element. A loadbearing non-separating element carries only the first, a separating non-loadbearing element the next two, an element both loadbearing and separating all three.
Further supplementary letters exist for particular performances, notably radiation or self-closing, whose meaning is defined by the applicable European classification. Their presence is checked in the test report.
The structure of a reaction classification
The logic differs: it is a ranking, not a duration. The ranking bears on the product's contribution to the fire.
Products are classified by their contribution to fire, from a level corresponding to a negligible contribution down to a level with no determined performance. The class appears in the product's declaration of performance.
Two supplementary indices accompany the main classification: one bears on smoke production, the other on flaming droplets or particles.
Those indices are not incidental. A product may have a good main classification and a poor smoke index, and a requirement often bears on all three elements at once.
| Notation | Function maintained | Element concerned |
|---|---|---|
| R | Load-bearing capacity, ability to carry the loads | Load-bearing non-separating element |
| E | Integrity, stopping flames and hot gases | Separating non-load-bearing element |
| I | Thermal insulation, limiting heat transmission | Separating non-load-bearing element |
| REI | The three functions combined | Load-bearing and separating element |
| Associated number | Duration in minutes the functions are maintained | All categories |
Traps in reading
Four errors recur regularly.
Confusing the requirement with the product's performance. The requirement bears on the works as installed, not on the product in isolation. A high-performing door poorly fitted does not meet the requirement.
Ignoring the direction of exposure. Some performances are directional, and an element may be classified differently depending on the exposed face.
Overlooking the field of application of the classification. A performance is established for a defined test configuration, and transposing it beyond that field is not automatic.
Confusing former and current notations. The European system replaced earlier national notations, and an old document may use terminology no longer current. The correspondences are not simple translations.
What the notation does not indicate
Three useful limits.
It says nothing about installation. Fixing conditions, junctions and penetrations govern actual performance.
It says nothing about durability. Performance is established when new, under test conditions.
It does not dispense with checking compatibility. Assembling two high-performing elements does not necessarily produce a high-performing whole, particularly at junctions.
What this means for a professional
Four rules.
Reproduce the exact notation in the documents, without simplifying or translating it.
Check that the product proposed covers the actual configuration, not only the nominal performance.
Treat junctions and penetrations as a subject in their own right, since that is where performance is lost.
Be wary of old documents, whose notations may belong to an abandoned system.
This article reflects a method of reading at the date of checking and serves professional orientation. It does not constitute legal advice and does not replace consulting the applicable classification standards.