In many situations, timber and wood-based materials may be used in their natural, untreated state. However, flame-retardant (FR) treatments extend their use to situations that demand enhanced ‘reaction to fire’ properties.
This Wood Information Sheet (WIS) covers treatments that may be applied to wood and wood-based products both factory and site applied to upgrade their fire performance to Euroclass B or C or National class 1 or 2 (or Class ‘0’, found only in Approved Document B to the Building Regulations (before the 2019 edition), where it is defined by a combination of performance in tests according to BS 476 Parts 6 and 7).
There are three main types of FR treatments: impregnation of solid timber and panel products with liquid FR formulations using vacuum/pressure processes; incorporation of FR chemicals into the product at the point of manufacture; and surface coatings that may be pigmented or clear film-forming products or low-viscosity liquids.
Any additional coating that is applied to a product that has a proven fire performance will likely affect this performance.
It is important to ensure that the field of application (detailed description of the material and how it may be used) covers the intended end-use.