Abstract: An assembly or panels of rectangular shape, as for example, a floor, in which the panels comprise upper and lower rigid sheets separated by a core, elongated fittings extending along adjacent edges of adjacent panels and having lateral extensions received between edge portions of the sheets of the panels. Each fitting has an upwardly open channel located beyond the edge of the associated panel. Adjacent fittings, and hence adjacent panels are secured together by elongated connector strips which have parallel elongated lugs received in the channels of the adjacent fittings.