Love it! lets add that in. How does John make it around the floor boards?
Two things worth separating here, because they're actually different problems.
The floor mechanism. The way the chapter is written, the floor isn't pressure-plated — it's structurally overloaded by the weight of the drums. The joists are already at their limit. That's what he reads. The explosion isn't triggered by weight, it's triggered remotely — someone watching, waiting for the team to be inside and committed.
The trap failed not because John outthought the trigger, but because he got children out of the building before the button was pressed, and the man who pressed it either didn't know or didn't care.How he moves across the floor. He reads the joists through the boards the same way he reads everything.