Hot topic: significant updates to flame-retardants WIS

Significant revisions have been made to TRADA’s Wood Information Sheet Flame-retardant treatments for timber products, most notably on the greater importance placed on Euroclass classifications.

Flame-retardant (FR) treatments can enhance the reaction to fire performance of wood-based products. Reaction to fire performance is about combustibility and ignitability of a material (and, when tested to European standards, heat output, smoke and flaming droplets – as presented in this new update) rather than its ability to resist the passage of fire through building.

Another update makes reference to the fact that Euroclass classifications are the norm now since the use of product standards for flame-retardant treated timber is not mandatory. Manufacturers wishing to market products in the rest of Europe should follow the Euroclass system.

Flame retardants can be incorporated during production. This is often the case for engineered timber products, such as OSB, MDF and chipboard. This latest update highlights that products can be CE marked for structural and non-structural use ex-works, thereby allowing easy specification and compliance with the Construction Products Regulation (CPR).

Treatments applied on site are often surface - only treatments. These surface coatings have much the same range of types as the non-flame-retardant paints or varnishes – clear unpigmented varnishes, emulsion paints and matt or gloss oil-bound paints as well as acid catalysed systems.

Any additional surface coating that is applied to a product that has a proven fire performance will likely affect this performance. The addition of a decorative surface coating can make a significant difference to its performance, particularly in the Euroclass test methods.

The addition of varnishes, paints, coatings, veneers and laminates can often greatly decrease the performance of a flame-retardant product and new test evidence must be gained to prove that the new composite product still achieves the required performance. 

• Members can download a copy of the WIS Flame-retardant treatments for timber products.
• View our full list of Wood Information sheets.