Updated
Yale Night Latch Not Catching Or Locking
The front door will not stay shut, the latch does not click home, or the snib no longer holds the latch back.
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What's happening?
A night latch is the rim lock screwed to the inside face of a front door, with a cylinder through the door and a keep on the frame. It works by a sprung bevelled latch riding over the keep and dropping into it, so the whole thing depends on the latch meeting the keep squarely with the door closed. That makes it very sensitive to movement: a door that has dropped a few millimetres, a keep whose screws have loosened, or paint built up on the frame will all stop the latch dropping in. Inside the lock there is a spring returning the latch and a snib holding it back, and both wear. It is also worth knowing that a plain night latch is not automatically an insurance-grade lock. The British Standard for thief-resistant locks, BS 3621, covers night latches as well as mortice locks, and a Kitemarked one is stamped with the standard number on the lock.
What usually causes it?
- The door dropped or swollen, so the latch no longer lines up with the keep on the frame
- Keep screws loose in the frame, letting the keep shift out of position
- A weak or broken latch spring, so the latch does not return fully after each closing
- The snib worn or jammed, holding the latch back when it should release
- Paint or draught excluder built up on the frame stopping the door closing far enough
- A worn tailpiece between the cylinder and the lock case, so the key does not fully drive the latch
- Screws through the lock case loosened by the door being pulled shut hard
Is it dangerous?
A front door that does not latch is a door that can be pushed open, and it is worth solving the same day rather than relying on a chain or a bolt. If the door is a final exit, a night latch that has jammed on the snib can also stop people getting out, which matters at night.
Can I fix it myself?
Look at where the latch is striking. Close the door slowly and watch: if the latch hits above, below or short of the keep, the door has moved and the keep or the hinges need attention. Tightening keep screws and hinge screws is fair DIY, and so is clearing paint from the frame. Do not pack a keep out with washers or file it larger to make it catch — that reduces how far the latch engages, which is the part doing the securing.
When should you call a locksmith?
Call a locksmith when the latch or the snib has failed inside the case, when the tailpiece or the cylinder is worn, when the door needs easing rather than adjusting, or when you want the night latch upgraded to a Kitemarked BS 3621 version because your insurer asks for it. Front doors with a single night latch and no second lock are worth having looked at as a whole.
What will the locksmith actually do?
- Check where the latch meets the keep and adjust hinges or reposition the keep so it engages fully
- Strip the night latch to test the spring, the snib and the follower rather than replacing on assumption
- Replace a worn tailpiece or rim cylinder and check the key operates the latch fully from outside
- Fit a Kitemarked BS 3621 night latch where the door needs to meet an insurance requirement
- Assess the door as a whole, including whether a second lock or a deadlock is appropriate
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