Well unless you are away for an extended timeline while someone was paying more attention than normal even for a criminal your only real concern would be fire and more for the rest of the house. Probably be another 15 years before we do something similar.

Walls are double reinforced with steel studs and 3/4 inch plywood on both sides lined with fire board on the inside. The floor/ceiling also has steel studs and 3/4 plywood lined with fire board. The door is a walk in style from an old bank I found online with it’s original steel framework. Considering the amount of $$$ I have invested in the contents of that room no expense was to great to protect it.

Would be more space efficient and assuming you included the walls involved.