Cavity Surfaces in External Wall Construction

In the case of an external wall construction, of a building which, by virtue of paragraph 4.40(d) (external cladding system with a masonry or concrete inner leaf), is not subject to the provisions of Table 4.7, the surfaces which face into cavities should also meet the provisions of Table 5.1A, and provisions for cavity barriers in Section 4, but where Regulation 23(2) applies, that regulation prevails over guidance provided in Table 5.1A and Section 4.