Space separation and protection against external fire spread

Protection against the external spread of fire from one building to another is related to – (i) the distance between a building and each of its relevant boundaries (see paragraph 5.9); and (ii) the extent of the unprotected area in the side of the building which faces that boundary. The basic provisions are outlined in paragraph 5.13 and methods of meeting those provisions are given in paragraphs 5.14 to 5.19. The provisions are based on a number of assumptions, and whilst some of these may differ from the circumstances of a particular case, together they enable a reasonable standard of space separation to be achieved. The provisions limit the extent of openings and other unprotected areas in the sides of a building (including areas with a combustible surface) which would not give adequate protection against the external spread of fire from one building to another.