29 September 2020

Major revision to WIS Wood-based panel products and timber in fire

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The Wood Information Sheet (WIS) Wood-based panel products and timber in fire covers the behaviour of wood-based panel products such as plywood, particleboards and fibreboards as well as timber when they have been exposed to fire conditions.


Intended to aid designers, specifiers and manufacturers in ensuring compliance with UK regulations and other jurisdictions where British practice is followed, the WIS details the phases of fire development, reaction to fire, European test standards, fire resistance, smoke production, and fire performance during construction.


Following a general review along with changes to Building Regulations and British Standards, the WIS has undergone the following changes.


Major changes

  • It now explains the systems of testing based solely on European tests, since the European system is accepted in all European countries and will continue to be the recommended testing system in the UK even after Brexit.
  • It acknowledges that there are two separate Approved Document Bs – one for England and one for Wales.
  • It takes into the account the amended Building Regulations in the UK with the introduction of an amendment to Regulation 7 – Materials and Workmanship and Approved Document B requirement B4, which requires that materials which become part of an external wall of a relevant building are of European Classification A1 or A2-s1,d0. This means that timber products cannot be used on the external walls of buildings with a storey height over 18 metres.
  • It acknowledges that similar regulations and guidance has been published in Scotland and Northern Ireland, with a limit of 11 metres in Scotland.
  • Table 3 was amended due to standard updates.
  • Definition of reaction to fire updated to reflect definition given in BS 4422.
  • Updates to the fire resistance of plywood.
  • The section on smoke control has been removed, since this was more about doorset testing and not wood-based panel products.


Members can download a free copy of the WIS Wood-based panel products and timber in fire. WIS sheets are available to non-members too – purchase a PDF or a hardcopy at the TRADA Bookshop.