Quite a few of our classics sleep in garage boxes. Many of those garage boxes are on squares where they can only be seen by residents. They are often equipped with up-and-over doors that close onto a strip built into the floor.
And did you know, by the way, that the clearance in such a locking system is so great that the lock pin can usually be taken over when the door is 'lifted' with a sturdy crowbar?
The cheapest solution is to make a turn slider on the upper frame edge. Mounting two locks in the uprights of the door frame is already a nicer option. If they do then
also sit on a crossbar behind the door that improves their resilience considerably .. Consult your local Gamma or Praxis.
A completely different category of intruders has also fitted it on your classic: rodents. Therefore keeps rodents behind mesh.
Rodents are classic enthusiasts. Such classics are dry, equipped with all kinds of stuff that can be nibbled or nestable and the thing is usually left alone during the coldest time of the year.
The purchase of an ultrasonic pest expeller pays off, but the sealing of the wall ventilation slits can also keep intruders away. Do not use chipboard or PUR for that, they will eat through it.
And if the case is closed with mesh, do it with the finest metal mesh. Because even full mesh is a challenge for many mouse, not a blockage.