Provision of cavity barriers - general requirement

To restrict the spread of smoke and flame through concealed spaces in the construction of a building, cavity barriers should be provided – (a) in a building of any purpose group – (i) at the intersection of fire-resisting construction and an element containing a cavity as shown in Diagram 4.4; and (ii) as set out in Table 4.6 for the appropriate purpose group of the building and the specified locations. [Note – alternative arrangements for items 1, 3 and 4 are shown in Diagram 4.5 and for item 2 in Diagram 4.6. Notes (3) and (4) to Table 4.6 are supported by Diagrams 4.7 and 4.8 respectively]; and (b) in a building of Purpose Group 2, 3, 4, 5, 6 or 7 – so that the maximum dimension of a cavity, (other than one described in paragraph 4.40 or 4.41) should be not greater than that given in Table 4.7 for the appropriate location of the cavity.