A cavity barrier

A cavity barrier 1 for installation in a cavity 8, between first 4 and second 6 opposed walls of a building construction, so as to surround an opening for a conduit 9 wherein the barrier includes a unitary body portion comprising: a first surface 16 for location against the first wall and an opposing second surface 18 for location against the second wall, a hole extending through a depth of the body portion, from the first surface to the second surface, for receiving the conduit 9, an interior surface (22 Fig 2) defined between the first and second opposed surfaces by the through-hole; an opposing exterior surface (24 Fig 2) extending between the first and second opposed surfaces; and a thickness T extending around the through-hole, from the interior surface to the exterior surface; wherein a minimum thickness Tmin (Fig 4) of the body portion is greater than or equal to 0.65 times the depth D (Fig 3) of the body portion. A minimum thickness Tmin of the body portion for providing adequate fire integrity and/or insulation in the cavity 8 varies with the size of the cavity 8 and, in turn, the depth, D of the body portion 12.