Fire classification: EN 13501

Two separate questions, two separate classifications

The EN 13501 series describes two independent things.

How the material contributes to fire

This is the classification under EN 13501-1: A1, A2, B, C, D, E, F, with additional markings for smoke production (s1, s2, s3) and flaming droplets (d0, d1, d2). It describes whether the material burns, how much heat it releases, how much smoke it produces and whether burning material falls from it.

How long the structure resists

This is the REI system, with a time in minutes. It describes how long the structure performs the function expected of it. Testing follows a standard fire curve on a real structural specimen.

Why one does not replace the other

Steel is non-combustible, so in terms of material classification it is in the best category. Even so, the fire resistance of a thin-walled steel structure may be poor, because the section heats up quickly and loses its capacity.

The opposite also occurs: a build-up containing combustible material can achieve good fire resistance if the protective lining shields the structure in time.

So looking at a product datasheet is not enough: the question is always whether there is verification for the structure.

Where material class does matter directly

In some places the regulation sets a requirement on the material itself rather than on the structure:

• in facade build-ups, to limit fire spread,
• for linings on escape routes,
• in cavities and ventilated air gaps,
• generally in some higher risk classes.

There it is not enough that the structure is fire resistant: the material of that layer must also meet the required class.

CE marking and classification

Reaction to fire class appears in the product’s declaration of performance — it is one of the performance characteristics the manufacturer declares. Fire resistance, however, is not a product characteristic, so it cannot appear the same way in a board’s declaration of performance.

The point

Material class is on the product’s paperwork, fire resistance is on the structure’s. Swapping the two is where “but it is non-combustible” conclusions come from.