Essential guidance about flame retardant treated wood and panel products

The Wood Protection Association (WPA) announces publication of a new edition of its manual dealing with the fire protection of wood and wood based panel products. The manual (Ref: FRSM/E3 October 2016 ) is published as an electronic pdf and is available now in the publications section of

Verification of quality, fitness for purpose and declarations of performance are vital when specifying flame retardant protection for wood. This new WPA manual helps designers get to grips with the big specification issues and avoid the consequences of getting it wrong.

Fire safety is a critical factor in building design and where wood is the material of choice this manual is designed to provide clear guidance about how to ensure the right flame retardant (FR) treatment or FR treated panel is specified for the project.  WPA Director Steve Young describes the manual as setting a new generic guidance benchmark for those involved in building design or building control by placing emphasis on procedures that verify quality, fitness for purpose and the performance claims made by a supplier. He says “This new manual deals exclusively with quality assured products applied by a controlled industrial process. All of the processes and wood species described are commercially available, tried and tested and capable of meeting the reaction to fire performance required in the Euroclass standards that now apply in the UK.”

The WPA Commodity Code system simplifies the FR specification process

The scope of this new WPA manual includes generic guidance about choosing the right FR product for use in three distinct application categories or FR types: dry interiors (INT1), humid environments (INT2) and externally exposed timber (EXT) where leach resistance is a key requirement. Model specification clauses for European standards of fire performance (Euro classes) are provided for a designer to cut and paste into project specifications or BIM systems but extended guidance about a specific timber component is given in the section featuring the long established WPA Commodity Code System of specification. This system enables a specifier to simply match the timber component requiring FR protection to one of five application groups and quote the WPA Commodity Code into the specification or BIM system. For example: For non loadbearing internal wood and wood based panels WPA/FR1 is the code. For internal loadbearing wood it is WPA/FR2 (See the adjacent panel for all five codes and typical applications).

Case Studies of building projects and the details of the flame retardant treatment and WPA Product Type (Int1, Int2 and EXT) are featured throughout the manual as examples of FR specification good practice.

Recently the WPA expanded the scope of its ‘Benchmark’ Quality Assurance and Product Approval Schemes to include flame retardant treatments, treatment processes and wood based panels. FR products and processors approved under the WPA Benchmark scheme are listed in the Manual along with details about the scope of their approval, species and sizes.

Euroclass and BS standards are not interchangeable

The WPA is keen to emphasis that those responsible for specifying the materials used in a building have a duty of care to ensure that the materials they specify are fit for purpose. Reaction to fire specifications calling up BS476 Class O and Class 1 performance appear in Building Regulations as alternatives to Euroclass B or C specificiations. It is wrong however to assume that the two standards are interchangeable. They are not. Wood and wood-based panels treated to BS 476 classifications are no longer widely available and the reaction to fire test methods and the interpretation required for Euro class B and C protection are completely different. WPA director Steve Young says: “The introduction of Euro classes and new European Standards make it essential that specifiers check that appropriate fire performance certificates are in place for the FR treatment.” The WPA is extremely concerned that some specifiers may be being misled into assuming a ‘one-size fits all” approach is applicable to fire certificates. Steve adds: “Specifiers need to be 100% sure that the scope of the fire certificate/classification report quoted by the FR supplier extends to their application if there is any difference in the species size and installation design between the certificate and that which they want to use.

Flame Retardant Specification Check-list

The WPA says that as society has turned increasingly to wood as a sustainable, low carbon material for construction, the number of flame retardant products offered in the UK has grown significantly. WPA is aware that some of the products offered as off-the-shelf FR solutions make performance claims that just do not stand up to scrutiny. To help designers sort the good from the not so good WPA has developed a six-step FR Specification Check-list in collaboration with Exova, the global leader in independent fire testing. “Using this Check-list will help specifiers avoid the consequences of choosing unsuitable or unproven fire protection products in safety-critical situations.” say the WPA.

WPA Commodity Code System of Flame Retardant Specification

The WPA commodity code system makes choosing flame retardant materials simple. The system is called up widely by other standards setting bodies in the UK.

WPA Code

Specification group

Typical applications


Wood and wood-based panels for non load-bearing interior use (BS EN 1995 Service Class 1)

All linings





Wood and wood-based panels for load-bearing interior use (BS EN 1995 Service Class 1) 

Roofing membranes

Support structures & frames 

Support columns 

Flooring, where humidity is not a consideration


Wood and wood-based panels for interior use

(BS EN 1995 Service Class 2)

Swimming pools

Leisure centres

Hospitals & Schools

Agricultural buildings


Wood and wood-based panels for weather-protected exterior use (BS EN 1995 Service Class 2)

Covered walkways

Protected overhangs

Exterior cladding with weather resistant coating

The WPA Flame Retardant Specification Manual cost £45 and is published in electronic format

Posted at 1:37 pm on October 12th, 2016