Abstract: A device for fastening sheet material, such as plastic sheeting, to a framework, such as a greenhouse construction, composes longitudinally extending channel members firmly attached to the framework at selected parallel locations, the channel members having opposing, outwardly projecting longitudinal flange portions which converge slightly towards each other to define a dove-tail cross-section groove. The entire network of channels is overlaid with the sheet material and the sheet material is depressed into the channels and held therein by a resilient retaining member, such as a zig-zag spring member which is operatively inserted into the channel and held therein by the converging flange portions, thereby positively connecting the sheet material to the channels and the framework. The sheet material is easily removed from the channel members and different thicknesses of sheet can be accommodated.