Abstract: A clip for retaining sheet metal roofing or siding panels on a structure, while providing for thermal expansion and contraction of the panels, is made from a single piece of sheet metal. The metal is cut and bent so as to form a base portion having panel supporting embossments, and an upright portion which has panel retaining bulbous projections adjacent the top edge. Preferably there is an even number of these bulbous projections and they alternate projecting to opposite sides of the upright portion. Most preferably, the clip is made of stainless steel when it is intended for use with aluminum panels. The clip is adapted to have its base portion affixed to a building structure and its upright portion enclosed within the seam joint between two adjacent metal roofing or siding sheets which are formed over the bulbous projections of the clip.