Regulations and Fire Safety led by Dame Judith Hackitt in the wake of the Grenfell tragedy tackles head-on the significant shortcomings in the control of building standards, compliance and competence in the supply chain.

From our own direct experience and from members’ reports, the Wood Protection Association (WPA) would completely agree with the review conclusions. Effective fire retardance is safety critical and it is crucial that specifiers and users of flame-retardant enhanced wood products insist on the right product for the job and that there is traceability through the supply chain to ensure that the right product is delivered to site and installed correctly. Lives are at stake.

In the critical early stages of a fire, it is the ‘reaction to fire’ properties of the various materials exposed that are vital – ie ignitability, heat, smoke, burning particle release and subsequent spread of flame across the surface.

Once a fire is more developed, then containment becomes the top priority in design with the use of compartmentalisation a common strategy. At this stage of a fire, it is the ‘fire resistance’ ratings of building elements such as walls, floors and fire doors that then becomes critical (for example, 30, 60 or 90 minutes fire resistance).

There are two tried and tested ways that flame-retardant properties can be effectively conferred on wood and wood-based materials:

  • The treatment of finished products using either high pressure impregnation or the application of a suitable flame retardant surface coating, applied under factory controlled conditions that are independently quality assured, or;
  • The incorporation of a flame retardant as part of product manufacture (for example, FR MDF, OSB or plywood). Flame retardants work by making wood more difficult to ignite and by slowing the rate at which the timber burns, so improving the performance of wood and improving its reaction to fire rating from Euroclass D to either Euroclass B or C, enabling compliance with Building Regulations.

It is important to note here that the brush or spray application of an FR coating on a construction site is not recommended, as achieving the required loading/thickness consistently cannot be guaranteed or verified.

The WPA operates complementary quality schemes to verify that a flame-retardant product will perform effectively and that the wood has been processed appropriately for its end use. These are:

  • A flame retardant formulation Product Approval Scheme, and;
  • A treatment process quality assurance scheme called ‘WPA Benchmark FR’.

The product approval scheme involves an in-depth review of fire test data on particular flame retardant formulations by an independent panel of experts. The WPA Benchmark FR scheme includes an independent audit and quality assurance check on companies applying these formulations.

Any flame-retardant treatment must provide long-term, predictable performance backed by independent verification. Before specifying a flame retardant, it is vital that the specification fundamentals are established first:

  • What fire performance is required – Euroclass B or C in accordance with BS EN 13501?
  • What is the service environment? Flame retardant formulations fall into three categories – Type INT1 (dry interior applications), INT2 (humid interior and semi-protected) and EXT (exterior use).

For peace of mind those checking compliance should ask for:

  • Fire test certification and Euroclass Classification Report relevant to the service environment (Type), wood species and thickness in question. Do not accept approximations or cross references to another species or profile.
  • Proof of WPA FR Product Approval status (ie, the approval certificate).
  • Evidence of treatment, where applicable, and confirmation of specification applied (delivery note, invoice, treatment certificate).
  • Guidance on the safe and effective installation of the FR enhanced wood product.

Always check that the description and scope of the material given in the Fire Classification Report quoted by the manufacturer can be taken to apply to the material to be used in the project.

Always select a flame retardant with a verified performance. If no Classification and/ or Extended Application Report is available, then choose another product where the required performance has been verified