Approved Document B (fire safety): amendments to statutory guidance

The Building Regulations 2010 [SI 2010/2214] require that external walls on all buildings resist fire spread. Statutory guidance in Approved Document B (fire safety) sets out two ways that external wall can meet the Building Regulations requirement to resisting fire spread:

  • The first is for each individual component of the wall (insulation, filler etc.) to meet the required standard for combustibility; and
  • The second is to ensure that all the combined elements of a wall, when tested as a whole installed system, adequately resist the spread of fire to meet a set standard.


Appendix A of Approved Document B outlines how tests should be carried out for the performance of materials, products and structures and establishes the principle of assessments in lieu of test. The term ‘desktop study’ has commonly been used to describe an assessment in lieu of test, with respect to external wall insulation and cladding systems.
One of the recommendations of Dame Judith Hackitt’s Interim Report on the Independent Review of Building Regulations and Fire Safety was that:

‘The Government should significantly restrict the use of desktop studies to approve changes to cladding and other systems to ensure that they are only used where appropriate and with sufficient, relevant test evidence. Those undertaking desktop studies must be able to demonstrate suitable competence. The industry should ensure that their use of desktop studies is responsible and in line with this aim.’

In order to implement Dame Judith’s recommendation the Government is proposing to issue amendments to Appendix A of Approved Document B which clarifies the existing text and creates new requirements for desktop studies.
This consultation is also seeking view on whether the Government should go further and prohibit desktop studies either for all fire test classification or for fire test classifications relating to the BS 8414 full-scale cladding test.
Link to consultation.
Consultation ends: 25th May 2018

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