Chain locks find their way onto doors in many homes. These are considered a decent form of security. They also have the perk of allowing you to partially open the door without unlocking it completely. The method of installation has a lot to do with the security level provided by these locks. A weak installation will result in a weak lock.
Decide on the color of the lock.
These locks come in mostly brass, bronze, or stainless steel colors. In this day of designer everything, there may be other colors available for a price either online or at large home stores. Color is unimportant as long as the lock is secure. However, it may be possible to have a color that matches your décor and give good protection.
If it needs to be your most secure door lock, buy a heavy duty model.
Thieves learn how to break locks. Chain locks have two weak points. No chain lock is stronger than its chain. The second potential weak area is the type and length of screws used to fasten to the door and wall. Door construction can also be an issue but not as much as the first two items.
If possible, position it as far from a window as possible.
When someone wants to invade your home, try not to make it easy. Putting a chain lock near a piece of glass that is easy to break is a problem. The intruder can simply break the glass, reach inside, and unlock the chain lock.
Use screws that are as long as possible for your situation.
If you install a chain lock with screws one inch or less in length, you might as well just leave your door standing open. With only moderate force, someone can cause these screws to rip from the door or post and come inside. Use the largest and longest screws that your door, lock, and door posts can receive.
Close the door and mark the location of the lock on the door and door post.
Start the installation by placing marks on the door at the point where you will be fastening the receiving part of the chain lock. Make similar marks on the door post adjacent to that edge of the door. Use a level to make sure that you are installing the lock parts at the same height. Be careful to place them close enough together so that the chain will reach and allow you to lock the door.
Attach the receiving end of the lock to the door.
The thickness of your door will dictate the length of screws that can be used. Do not over tighten the screws because they can strip out the wood in the door and not allow the screws to hold the lock in place. Repeat the process on the door post with the piece of the lock that has the chain.
Fasten and unfasten the chain a few times.
Make sure that the lock can be fastened. Once it is apparent that the chain will reach and connect the two pieces of the lock, the installation should be complete.