Euroclass D fire rating

Timber behaves very predictably in fire situations, and there are well established parameters for its use in building construction. The fire performance of non-fire treated wood panelling can be defined under the established CWFT rules (Classification Without Further Testing), set out in EN14915.

Thermopine coated in SiOO:X Mid Grey on the Dornoch project by mi architects — Thermopine® Cladding RW119 factory coated SiOO:X Mid Grey | Graham Niven Photography

SILA Select® Cladding in RW006 profile | Royal Veterinary College | NORR Consultants Ltd

How to achieve a Euroclass D rating

The reaction to fire performance of solid wood depends on the type of wood, its density, thickness, arrangement and installation.

A Euroclass D rating can be achieved under CWFT rules where the following conditions are met.

Profiles are of nominal thickness ≥ 18mm
Species density is over 390kg/m³
Back wall/substrate is A1/A2 fire rating and minimum density 10kg/m³
Where the cavity is non ventilated with a depth <20mm or no airgap (eg internal wall panelling), a Euroclass D- s2, d0 substrate may be used.
The cladding arrangement is of closed jointed type*

(*Open jointed arrangements may be classified as D-s2,d0 under CWFT rules in certain specific arrangements, see EN-14915)

Reference image for Euroclass D cladding arrangement

Isometric diagram

Where timber frame buildings are concerned, and if not already included within a SIPS panel system, a suitable sheathing board should be used to cover insulation (eg exterior Gyproc), to give an appropriate fire resistance rating where required.

1. Insulation material / other wall build up arrangement

2. A1 / A2 sheathing board

3. Ventilated cavity with the batten system

4. Cladding boards

The information on this page is for reference only. Please consult with Building Control for advice on your project.