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Last edited 20 Aug 2017

External fire spread: building separation and boundary distances (BR 187)

BRE is the UK’s leading centre of expertise on the built environment, construction, energy use in buildings, fire prevention and control, and risk management.

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External fire spread: building separation and boundary distances (BR 187) was published by BRE on 16 June 2014. It was written by Richard Chitty.

The aim of calculating building separation distances is to ensure that ignition of a building adjacent to a fire is delayed sufficiently to allow the fire and rescue service to arrive and take preventative action. The 68 page guide BR 187 describes methods for calculating adequate space separation between buildings.

BR 187 was first published in 1991, when it was a two-part guide. Now in its second edition, it has been merged into one part, and substantially updated and improved:

  • It has expanded sections, including flame projection from windows.
  • It provides more methods of calculation and more illustrative examples.
  • It updates the theoretical background.
  • It presents detailed analysis of methods so users can create their own fire engineering software.
  • It uses more recent experimental data.
  • It defines thermal radiation and associated terminology.
  • It includes the background to methods 1 and 2 of approved document B of the building regulations.
  • It describes the development of boundary distance requirements in the building regulations since World War II because of its relevance to the redevelopment of sites containing existing buildings.

The contents of the guide include:

  • National building regulation guidance.
  • Glossary of terms, and symbols.
  • Principles.
  • Calculation methods.
  • Case studies.
  • Fire engineering approaches.
  • Appendix A: Transfer of heat by thermal radiation.
  • Appendix B: External flaming.
  • Appendix C: Evolution of ‘simple’ methods in Approved Document B.
  • References.
  • Tables for calculations.

See also: External fire spread, Supplementary guidance to BR 187 incorporating probabilistic and time-based approaches.

--BRE Group

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