The best option for security is a multi-point lock. By definition, multi-point locks secure the door to the frame or astragal at multiple points. This locking system provides a better seal, and enhanced security for your home. However, multi-point locks require additional preparation in the face and edge of the door, as well as the frame. The lock mechanism sits in a pocket in the edge of the door and the edge needs a channel routed to connect the mechanism to the other points of contact.
Multi-point locks are especially beneficial in two scenarios. First, with 8’ tall doors, to prevent warping and maintaining a good seal the entire length of the door. In fact, you’re doing your customer a disservice if you don’t highly recommend multi-point locks with all 8’ tall doors. And second, in extreme wind situations, when the pressure is so great that it could separate the door and weather strip, creating a leak.
There are some special considerations regarding double door applications. First, installation is more critical than for single units. The unit has to be square for the door panels to meet evenly. It’s imperative that the head jamb be secured as well. The head and sill capture preps for flush or astragal shoot bolts are done in the field. The head jamb capture plate needs to be mortised into the head on site, and make sure the sill capture cup supplied is caulked in place to avoid possible water infiltration.
For double doors, the decision must be made whether the inactive door will receive any prep. Most inactive handlesets simply screw to the face of the inactive door, leaving an aesthetically pleasing look on the inactive door that matches the active door.