Assemble and join square ducting by placing the L-shaped sections together, applying the S-hooks, sliding two pieces together and joining them with drive cleats. Finish by sealing the connection with duct tape.
Examine the L-shaped metal pieces that make up a duct, noting that one side has a straight edge while the other includes U-channels. Place them together so that the U-channels make up the sides, and push the top downward to form the duct. Place one metal S-hook on each straight edge to create a space for the other duct piece to slide on. Fit another duct piece into the S-hook channels of the prepared piece, and place one drive cleat at each U-channel.
Push downward on the cleats while engaging the channels, and secure the cleats by tapping on them gently with a hammer. If the hammer causes any dents or dings, straighten the cleats again using a screwdriver. Once the task is done, approximately 1 inch of the cleat should extend below and above the edge of the duct. Use the hammer to tap and bend down the edges that stick out so that the duct work is flat, securing the connection. Homeowners can also choose to apply an adhesive gasket to the edge of the duct and screw the pieces to each other rather than using drive cleats. To finish the process, seal the seams with duct tape.