How to Check The Deadlatch Feature of a Lock

Most lock manufacturers have designed a deadlatch feature into their entry locks to prevent the bypass of the lock with a credit card or similar material. Malfunctioning or improperly installed deadlatches will defeat this very important safeguard. Here is how you can check to see if a deadlatch is working properly.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• knife or ice pick

1. 
    
   deadlatch

   The first step is to visually inspect the deadlatch. Sometimes the deadlatch will break or get jammed in the latch body. In either case, the deadlatch needs to be replaced.
   
   Passage and privacy function locks do not have a deadlatch feature, but all entry or storeroom function locks should. The deadlatch is the small part along the flat side of the latch that can be depressed with the latch.

2. Push the latch and deadlatch in. Then release only the latch, keeping the deadlatch mechanism depressed. With the deadlatch mechanism depressed, try to push the latch in again. If the deadlatch feature is working correctly, the latch cannot be fully depressed if the deadlatch is already in the depressed position. There is usually some movement of the latch, but you should not be able to fully depress the latch.

3. The last step simulated what happens as a door closes. When the latch contacts the strike, the latch and deadlatch will be depressed. If the strike is positioned correctly, the deadlatch mechanism will remain depressed as the latch falls into the strike when the door is fully closed.

4. If there is a large gap (over 1/8 inch) between the door and the strike, it is possible that the deadlatch mechanism is not depressed enough to function correctly. Close the door slowly while observing the latch from the inside. If you observe the deadlatch mechanism falling into the strike hole, the strike needs to be repositioned.

5. With the door closed, if you are unsure if the deadlatch mechanism fell into the strike hole or if there is a considerable gap between the door and the strike plate, use the tip of a sharp knife or an ice pick from the inside of the door to see if you can manipulate the latch. If you can retract the latch enough to open the door, the strike plate must be adjusted.

Tips & Warnings

• If the gap between the door and the strike plate is excessive, you can sometimes stack an additional strike plate on top of the original one to correct the problem.
• If the strike plate requires a minor adjustment (towards the exterior if the deadlatch mechanism is falling into the strike hole), it may be a good idea to replace the strike with a larger high-security strike so that the new mounting screws will not be too close to the old screw locations.
• This is a common problem with, not only amateur installations, but also in new construction. Thick weatherstripping may allow the door to move further than necessary to close, allowing the deadlatch to fall into the strike. In these cases, it is sometimes possible to place small bumpers or spacers behind the weatherstripping in order to prevent the door from travelling too far.
• This is a good time to check the length of screws used to attach the strike plate to the door jamb. Most locks come with short screws that only attach the plate to the trim. Use 3 inch wood screws to attach your strike plate in order to tie the plate into the structural wood framing. This makes it far more difficult for anyone to kick in or otherwise force the door open. It is important that the screws used to attach the strike plate for deadbolt locks also tie into the structural wood framing for maximum effectiveness.

Resources

• Altic Lock Service