How does cladding react to fire ?

The CPR requires the reaction to fire performance to be justified using the European Euroclasses classification, in accordance with NF EN 13501-1: classification based on reaction to fire test data. As a result, the French classification of materials' reaction to fire (M) can no longer be used. Proof of reaction to fire is recorded in a report: cladding is deemed to be Euroclass C if it has been the subject of a European classification report. For cladding with a finish, this must form an integral part of the classification report for the construction product concerned to prove that it does not affect reaction to fire performance.

With regard to European fire regulations, the products are classified A, B, C, D and E, with A being the best classification for fire resistance.

Wood cladding materials are classified according to a number of criteria.

Three factors define the Euroclasses reaction to fire classification:

1. Instantaneous energy released throughout combustion and total energy (letters A (A1 and A2), B, C, D or E. A being the best classification for fire resistance);
2. Opacity and smoke emission (s1, s2 and s3) ;
3. The formation of flaming droplets or debris (d0, d1 and d2).

Based on the tests carried out, the reaction-to-fire performance of a timber construction material has 3 ratings, each classified into 3 sub-categories:

Measurements of the degree of flammability and contribution to the spread of fire :

• A1: no contribution to the spread of fire ;
• A2: limited contribution to fire ;
• B: very limited contribution to the development of the fire ;
• C: limited contribution to fire ;
• D: acceptable contribution to fire ;
• E: acceptable reaction to fire.

Emission and production of smoke

• s1: low smoke emission ;
• s2: average smoke emission ;
• s3: heavy smoke emission.

The presence or absence of flaming droplets

• d0: absence of flaming droplets ;
• d1: limited flaming droplets (burning for less than 10 seconds) ;
• d2: unlimited projection of flaming debris.

The decree of 07 August 2019 requires a laboratory opinion on the material used on the façade of 3rd family collective buildings. Failing this, the material must be classified as Euroclasse A. The wood material is covered by a laboratory opinion. This is the CSTB guide on wood construction and fire propagation through facades.  It is therefore perfectly possible to use Euroclasse D or Euroclasse C cladding on a façade. Under no circumstances do the regulations require Euroclass B for external facades.

Sivalbp, a forerunner in fire-rated façade solutions, offers a whole range of solutions to meet the requirements of the building industry for Euroclass C and D cladding. These various fire-rated solutions have a natural, not conferred, performance and do not require chemical maintenance of the wood to maintain this fire performance. The solutions mastered by Sivalbp are offered in 4 ranges, with or without finish, each with its own aesthetic characteristics, from natural cladding to cladding with a wood tone, pre-weathered finish or darker tones.

When Euroclass D is required for certain types of housing, these solutions offer the advantage of a variety of species and saturation solutions.

When Euroclass C is required, the choice of Larch species in its natural state or with a finish is essential; its durability in terms of fire performance is natural. At Sivalbp, we offer several solutions for Euroclass C cladding on Larch.  Performance is achieved with different surface finishes (solid brushed or solid planed) and different profiles.

Please note that the reaction to fire of a façade also depends on compliance with specific installation conditions and the installation of the planks in accordance with DTU 41.2 (air planks with a maximum opening thickness of 40 mm, mechanical assembly on a framework classified as at least D, installation against a substrate classified as at least D, with or without a rain screen, classified as at least E). In all cases, the panels can be installed horizontally or vertically.

Do you have a project requiring fire resistance? Would you like better protection for your wooden facades and cladding? Consult our Sivalbp teams for your project and discover our range of fire-resistant wooden cladding.