The door latch can stick for a variety of reasons. In my experience as an expert, I have encountered three main causes for a sticking door latch: broken internal mechanisms, being jammed, and misaligned strike plates. Let me explain each of these in more detail.
Firstly, a broken internal mechanism is a common cause of a sticking door latch. This can occur when the latch becomes worn out or damaged over time. If you find that the latch sticks when you try to move the handle, but you can still press on it and make it slide back and forth, this could indicate a broken internal mechanism. The latch may not be engaging properly or may be getting stuck on worn-out components inside the door. In such cases, it is important to have a professional locksmith or handyman inspect and repair the latch.
Secondly, a door latch can stick if it becomes jammed. This can happen if there is debris or foreign objects obstructing the movement of the latch. For example, dirt, dust, or small particles can accumulate inside the latch mechanism, causing it to stick. Additionally, if the door has been recently painted or varnished, the paint or varnish may have dripped onto the latch, causing it to stick. In such situations, it is advisable to clean the latch thoroughly and remove any obstructions. A lubricant, such as graphite powder or silicone spray, can also be applied to help the latch move smoothly.
Lastly, a misaligned strike plate can also cause a door latch to stick. The strike plate is the metal plate on the door frame that the latch engages with when the door is closed. If the strike plate is not aligned properly with the latch, it can prevent the latch from fully engaging or disengaging, resulting in a sticking latch. This misalignment can occur due to settling of the door frame, loose screws, or general wear and tear over time. To fix this issue, the strike plate may need to be adjusted or realigned. This can usually be done by slightly loosening the screws holding the strike plate in place and shifting it slightly until the latch smoothly engages with it.
A door latch can stick due to broken internal mechanisms, being jammed with debris or foreign objects, or having a misaligned strike plate. It is important to identify the specific cause of the sticking latch and take appropriate measures to repair or resolve the issue. If you are unsure or unable to fix the problem yourself, it is advisable to seek the assistance of a professional locksmith or handyman to ensure the latch functions properly and provides adequate security for your door.