Edging strips for concrete floors employ parallel strips as lost formwork secured to removable timber formwork using a nailing bracket that has a horizontal plate section 32 and a vertical plate section 35, the horizontal plate section slides underneath one of the strips as the strips separate due to concrete contraction and supports a filler by bridging under the filler, the horizontal plate section comprises an elongate section of the horizontal plate section having lobes 33 and 34 at each end. These lobes are welded to the underside of one of the strips 11 or 12 with the other strip located on top of the elongate section. The vertical plate is a fixing plate 35 with predrilled holes for nailing to the timber form, the elongate section having tapered corners opposite each lobe and the vertical plate extending in a plane located between the lobes.