How to Install a Commercial Double Door Lock

Place the doorknob position template against both doors and mark the installation locations. Assemble the doorknob set and hold it up to the doors to make the markings if there is no template available. Mark the positions on the edges of the doors as well.

Drill out the holes where the doorknobs will be installed with large drill bits or hole saw bits, if necessary, to remove a large enough section of the door. Drill through the edges of the doors and into these holes to provide access for the latch between the knobs.

Set each doorknob inside its hole. Attach the doorknob, along with the included hardware. Slide the latch mechanism of each doorknob through the hole in the edge of the door so that it bumps into the main doorknob. Attach the sections of the doorknob together by twisting them into place. Test the door by opening and closing it to ensure it's properly installed. Make any necessary adjustments.

Hold the bottom door bolt near the bottom of one of the doors and near the floor. Mark the attachment screw holes for the bolt as well as the hole that the bolt slides into in the floor. Drill out these marked holes with a drill bit that is the same size as the attachment screws on the door and the same size as the bolt for the floor. Attach the bolt to the door by tightening the included attachment screws in place with the drill. Slide the bolt open and closed to check for a straight installation.

Attach the top door bolt in the same manner at the top of the door so that it slides into the top of the frame.