are applied to the shield 20 that form a water resistant seal between the shield 20 and members 30 33 of the frame typically the sealing elements are carried on the plate member to seal against upright members 30 of the frame and on the lower flange 28 to seal against the sill member 32 in alternative frame structures typically used in aluminium or upvc doors there is an upright member extending up form the sill 32 against which sealing elements may seal the sealing elements can be formed as elongate extrusions of flexible plastic material such as foam plastic or natural or synthetic rubber these extrusions are secured to the shield 20 by adhesive the sealing elements may be applied to the shield 20 during its manufacture or they may be supplied separately for application upon deployment of the barrier with reference now to fig1 and 2 a system by means of which the barrier 10 is retained in place within a doorframe will now be described the barrier 10 is provided with a plurality in this case four wedge elements 40 each of these is tethered to the barrier 10 by a length of flexible rope or wire 42 in order that they will not become separated from the barrier 10 each wedge element 40 includes a wedge shaped body within a sloping surface of which is.