Most school buses don’t lock. This is a safety feature so kids don’t get stuck on buses overnight. However, I want my doors to lock. I’ve seen solutions that other people have come up with. The most common is the three-prong deadbolt, similar to what Seinfeld has on his apartment door. However, it still allows for the door to swing a bit, so I wanted something better. I also wanted to be able to lock and unlock the door from either side. Some conversions just install a latch for a padlock. That’s not very secure and not very pretty. You can only lock or unlock from one side. Not very functional.
My door is an accordion door. In order to open it up manually, you need to push on the center and fold to the side. If you can’t push it, though, you can’t fold it, so it is essentially immobile. Therefore, I decided to put a lock in the floor that would brace the door from being pushed.
The first plan was to get a door handle similar to what you would find on a heavy steel double door in a school. When you pull the handle, a mechanism contracts a bar above and below the threshold of the door to allow it to swing open. These latches are prohibitively expensive, though. I thought I might try to do something with a garage door handle and some metal, but it seemed too complicated and those locks aren’t all that secure.
In the end, I decided to install a simple deadbolt down at the base of the door. It does what I need it to do. The downside is that I have to bend over to unlock it. The upsides are that it’s cheap, secure, has a solid lock that can be re-keyed, and I can lock and unlock it from the inside without a key!
If somebody wanted to get in, they would need, at minimum, a strong wrench to tackle some of the hinge and tracking hardware that is part of the original door construction. They could also try to break the window and unlock the other side. The door doesn’t rattle when locked, and is extremely secure in this state. At any rate, getting in would take time. I think it’s enough of a deterrent that thieves would move on to easier pickings.