The present invention relates to a tool for forming a joint in an interlocking side-lapped seam formed between first and second structural decking panels. The decking tool may include a frame, actuator, and arms with jaws, wherein the actuator forms a structural component of the decking tool and is located between the frame and the arms with the jaws. Moreover, the decking tool may further comprise one or more shields and jaw guards. The one or more shields may cover the arms on at least one side for protection. The one or more jaw guards may be utilized with or without the shields, and may or may not be integral with the shields. The one or more jaw guards have a number of benefits, such as protecting the jaws, positioning the jaws, being utilized as levers to help remove the jaws, and being utilized to prevent separation of the side-lap seam.