in turned lip 26 is beneficial for adhesive engagement and retention purposes as will be appreciated hereinafter but also acts as seating for part of the curtain walling bracket apparatus 14 as will be understood below preferably the interior side surfaces 28 of the fastening channel 18 are non planar by incorporating striations or thread engagement grooves along the longitudinal extents thereof the curtain walling bracket apparatus 14 comprises bracket element 30 blocking elements 32 and a preferably resin adhesive 34 in this embodiment the bracket element 30 includes a thermal break member 36 an adaptor member 38 and a bracket member 40 the thermal break member 36 is formed of a thermally insulating material such as plastics for example nylon the thermal break member 36 is elongate to preferably substantially match or exceed a base length of the adaptor member 38 and is preferably thick enough so as to be rigid or substantially rigid the thermal break member 36 also has a lateral extent which substantially matches or exceeds a lateral extent of the fastening channel 18 so that it can be seated thereon as mentioned above this enables the thermal break member 36 to extend in a lateral direction fully across a longitudinal opening to.