When discussing timber construction, the question of fire resistance often enters the conversation. In many ways, wood is an excellent material in a fire situation because its properties are predictable and, most importantly, it does not melt as metal beams are prone to do. Wood does burn and so in certain situations it cannot be used unless it is treated and/or protected in some way.
Practically every country in the world has developed a set of regulations concerning fire protection and the use of materials in construction. Invariably there are differences in test methods and classification systems, so a construction product made and used in one country cannot automatically be used in another unless there is some form of reciprocal agreement over fire regulations.
The European Commission recognised that national fire regulations inadvertently created trade barriers within the European Union and therefore developed a harmonised system of classification, testing and requirements of products in given situations.
Classification using test data from reaction to fire tests outlines the criteria and specifies the test methods used to classify products.
The classification system contains six classes (A1, A2, B, C, D and E), where A1 is the most fire-resistant. There is a second set of classes – A1fl through to Efl – for flooring products. The two sets are very similar in terms of criteria, however.
In addition, information must be given about smoke production for all products and the potential to form flaming droplets or particles for non-flooring products that are in classes A2 through to E. The smoke-forming grades are denoted s1 or s2 for all end-uses, where products in s1 produce the least smoke, plus there is a third category, s3, for non-flooring products.
For flaming droplets the categories are d0, d1 or d3, where d0 indicates that no flaming particles are formed within the parameters of the test.
This all sounds very complicated, but, for wood based panels it is not because plywood, OSB, particleboard and MDF all have the same EU fire class of Dfl-s1 for flooring products and D-s2,d0 for all other uses. It is a shame that the smoke categories are different, because I think it adds complication to a complex system. It is caused by the fact that there are only two smoke categories for flooring products.
The fire ratings of a panel can be improved by incorporating fire retardant chemicals during its manufacture, or applying them subsequently. If the CE mark of a panel indicates that its fire rating is better than D, then it must either have been treated in some way or is a cement-bonded particleboard, which has a classification of B-s1,d0.