Statutory requirements regarding the reaction to fire classification of façades in their end-use conditions

> Requirements reaction to fire*

To limit or delay the spreading of fires via the façade, the Royal Decree imposes various requirements with regard to the reaction to fire of façade cladding in its end-use conditions (in other words, as present on site). This means that when assessing the reaction to fire of the façade cladding, one must take into account the potential influence of the underlying material layers and the way in which they are fastened.

*Source: WTCB

The table below provides an overview of the reaction to fire requirements for façade cladding indicated in the revision in their end-use conditions.*

Building type

High buildings

Medium-high buildings

Low buildings
Not self-reliant (type 1)

Low buildings
Self-reliant and sleeping (type 2) or self-reliant and awake (type 3)

Façade cladding (¹)

A2-s3,d0 (²)


C-s3,d1 (²)


(¹) The doors, façade decorations, joints and technical equipment in the façade (e.g. signboards, lighting devices, air-conditioning grids, drain pipes, plant holders and wall penetrations for heating installations) are not subject to the aforementioned requirements, provided that their total visible surface makes up less than 5% of the visible surface of the façade concerned.

(²) Stricter than previous requirements.

*Source: WTCB


The new regulations specifically contain stricter requirements for high buildings (h > 25 m). Thus the façade cladding must meet the requirements of reaction to fire class A2-s3,d0 according to the NBN EN 13501-1 (6) standard or by means of a LARGE-SCALE TEST (for example SP FIRE 105).

MEDIUM-HIGH BUILDINGS (10 m ≤ h ≤ 25 m)

For medium-high buildings (10 m ≤ h ≤ 25 m) the requirements remain unchanged. In this case the façade cladding must at least meet the requirements of reaction to fire class B-s3,d1.

LOW BUILDINGS (h < 10 m)

For low buildings (h < 10 m), the requirements depend on the type of use:

  • non-self-reliant users (type 1; e.g. hospitals, prisons and nurseries): the requirements for the reaction to fire class of the façade cladding become stricter by moving to C-s3,d1

  • sleeping self-reliant users (type 2; e.g. hotels and apartment buildings) and awake users (type 3; e.g. office buildings, shops): the façade cladding must be in reaction to fire class D-s3,d1.

It is important to note that these requirements apply to timber façade claddings in their end-use conditions and not to the cladding as such.

*Source: WTCB

How should your facade in wood be constructed if it must meet the required reaction to fire class? Is every type of wood eligible and when should I have the timber treated with fire retardant? We answer your questions:


Do you wish to receive more information or advice concerning the reaction to fire classes, don't hesitate to contact our Technical sales advisor.