Fixing French Door Locking Mechanism Replacement
When it comes to locking your french doors, you want to ensure that they're safe. You can do this by selecting a lock that will secure your door without blocking airflow or impacting the aesthetic look of your room.
French door locks are usually a three-point lock system which includes flush bolts at the upper and lower edges of each door panel, and an operating door. This type of lock isn't easy to crack.
How to fix a French Door that isn't Locking

It could be a major safety risk in the event that your doors do not lock or latch properly. It could be a sign of a larger issue like a damaged or damaged locking cylinder. However, don't panic, you can usually resolve the issue in just a few steps.
The most common reason for doors that don't lock is because there is an obstruction that blocks the latch. This can be something as simple as a piece of dirt that has gotten stuck in the lock or it could be a problem with the latch itself.
You can confirm whether this is the case by looking at the strike plate (the metal piece that sits against the frame on the side of the door). If there is a small metal tab protruding from the strike plate, tap it gently using a screwdriver, then hammer it to bend it slightly, this will make the hole in the plate, allowing bolts can slide in more easily.
A seized latch could be due to improper installation or poor alignment. Lubricating the latch will help it work better, but will not fix problems with alignment.
If you don't have a strikeplate it's easy to install one. You'll need to take the body of the lock from the door (the part that attaches to the frame of the door) and replace the complete lock with a new one. This is an easy task that requires a phillips-head screwdriver and power drill.
It is a good idea to ensure that the lock is lubricated, especially the cylinder, regularly to make sure it works as well as possible. Use a silicone or graphite lubricant for this. Apply the lubricant to the cylinder and then turn it slowly several times until the cylinder moves freely.
A double-cylinder deadbolt can be more secure than a standard deadbolt when it is used on French doors. A lock that is a twist on the handle is not enough to deter burglars as a door deadbolt that has a thumb turn can be destroyed if you smash the glass.
How to fix a French door that won't latch
Often the issue is caused by the door latch not properly working with the strike plate hole. This is usually due to hinges that are sagging, however it could also be due to the location of the latch or the latch itself. You can use lipstick, or another similar marker to determine which one is responsible. The location of this mark will help you to determine the source of the issue If, for instance, it makes contact below the strike plate's hole, hinges are likely to be the cause, but when it's above, the latch position may be the cause.
When installing handles or a new lock mechanism on an external French Door it's important that the strike plate and latch hole locations are correctly aligned. This is especially true if a door has been closed for an extended period of time. In this period the door might have moved a bit. This is most common for composite and timber doors, as they are susceptible to expansion or contraction based on the weather conditions or the surrounding environment.
To fix this issue, remove the latch that locks at the top of the active door and unscrew it from the handle. Then with a chisel that is sharp and hammer, you can increase the strike plate hole in the door frame. This will allow you to place the latch in a more ideal position for the door. When the door is shut, it will shut without catching the frame.
Once the hole in the latch has been enlarged, carefully insert the new latch inside the strike plate hole and screw it into. Next, re-adjust the strike plate using the screw and hammer until it is in a more suitable position, then test the door. Make any adjustments needed.
The lock cylinder of external French Doors won't turn. This could be due to obstructions or wear and tear, but it's usually simple to fix. french door handle repairs may be blocked or the pins within the cylinder are worn. A simple cleaning can make a big difference in the performance of the mechanism, and it's definitely worth giving this a try. If the issue persists, it may be necessary to replace the lock cylinder.
How to fix a French Door That Won't Open
If your French door isn't locking due to dirt or other debris, it is likely that the mechanism is blocked. The first thing you should take is to ensure that the frame of the door is free of obstructions and that nothing is blocking the locking mechanism. There could also be a problem with the alignment of the French door and its frame. This could cause the French door to slide against the frame, resulting in jamming.
The lock mechanism itself is quite simple - the key rotates a spindle which is then able to move a bolt back and forth on a rail. If the handle is turning but the bolt isn't moving this could mean that something is stuck. It could be an issue with the mechanism of the lock itself, or it could just need some lubrication. Make use of a silicone spray. It will come with a nozzle that you can use to direct the lubricant directly into the mechanism. Spray liberally and rotate the handle to ensure the lubricant has gotten to all the parts of the mechanism.
You may also need to change the location of the latch on the French door. This is easy to do and is usually done from the outside of the door. If your French doors have just been installed they should be able to screw the latch and handle into place with no problem. If they're old you'll be required to mark the positions of the holes for the handles on the door as well as the latch on the door frame using an outline provided by the lock kit. Then, you'll need to drill the hole for the handle or knob at the correct height (commonly about 36 inches from the floor) and then make a smaller hole along the door's edge to install the latch.
After the hole has been drilled it is important to make sure that the latch plate is properly placed over the strike plate that is on the door frame. If the latch plate does not fit properly the deadbolt will not retract into the strike plate if you push the lock lever. Finally, you will need to screw the latch plate into the correct position.
How to fix a French Door that won't close
Sometimes, the latch on a French door can become stuck, and it isn't able to close, making the doors unusable. This is usually a simple problem to fix, however it may require removal of one of the doors that are heavy. The most common cause is that the latch is not aligned or with the strike plate, or with the door jamb or both. It might also be that the dead bolt isn't being extended or retracted completely. The misalignment can happen with time, due to weather conditions or the settlement of the house.
If the latch is stuck, it may be difficult to open, but it's generally easy to fix the problem by loosening the screws holding the hinge to the frame, and then inserting shims to make the door a bit higher or lower. This will allow the latch to be closer to the lock mechanism, and fix the problem.
In the same way, if the latch isn't able to get into the strike plate hole in the jamb of the door typically, you can fix it by loosening the screw that holds the strike plate and using an electric or metal planer to cut away some of the edge of the plate until the latch fits. This could also mean removing the strike plate and then chiseling out the hole to make it larger should it be required.
The locks on French doors are often unable to latch properly. If you have a newer lock it could indicate an issue with the locking cylinder itself. You'll need to take off the lock and check it for visible damage or obstructions and if it's not working properly you may need to replace it.
If you have an older door that has a draught coming in, consider replacing the weatherstripping that was used on the outside of the door. This will create a tight seal and prevent the doors from catching. Door sweeps can be used to fill in any gaps. If you decide to do this, make sure to install the sweeps on both sides of the door and ensure that the sweeps overlap at the bottom.