Combustible materials permitted in cavity walls

Combustible material should not be placed in or exposed to the cavity except for – (a) timber lintels, window or door frames, or the ends of timber joists; (b) pipe, conduit or cable; (c) d.p.c., flashing, cavity closer or wall tie; (d) thermal insulating material; or (e) a domestic meter cupboard provided that – there are no more than two cupboards per dwelling; the opening in the outer wall leaf is not more than 800 mm x 500 mm for each cupboard; and the inner leaf is not penetrated except by a sleeve not more than 80 mm x 80 mm, which is fire-stopped.