The button punch is a non-proprietary option for connecting the sidelaps of adjacent steel deck sheets. The pea sized button punch is installed on a male/female, interlocking side lap with a crimp style tool. The shear strength of a sidelap connected with button punches is relatively low compared to the stronger alternatives, such as the PunchLok System (VSC) or a top seam weld. Diaphragms utilizing button punches at the sidelaps often cannot meet the higher shear requirements of West Coast, seismic-driven design.
Button punches are most commonly used to connect the sidelaps of floor deck. The purpose of a sidelap connection for floor deck is to limit the differential deflection of adjacent sheets during the concrete placement. If the relative deflection between two adjacent sheets of deck is large enough concrete may spill through the opening. As a rule of thumb, an average-sized person should be able to stand (not jump) on the male flute adjacent to the sidelap attachment without the joint separating. After the concrete cures, the sidelap attachment strength is not considered for the composite assembly diaphragm strength.