# Can a building destroyer destroy a screw pump from the z level above its impassable tile?

If I build a screw pump in such a way that its only exposure to outside is the top surface of its impassable tile, can it be destroyed by a building destroyer?

The exact setup is:

z-level +1:

``````F F F
F I F
F F F
``````

z-level 0:

``````O O O
O I P
O O O
``````

...where "F" is a floor, "O" is open space, "I" is the impassable tile of a screw pump, and "P" is the passable tile of a screw pump.

The building destroyer does not have any other valid path to the screw pump on its own z-level (I know this matters for destroying locked floor hatches from below). It is approaching from above the pump (z-level +1).

• Not sure, but I'd say that it is possible. As an analogy of sorts, Dorfs can acually dig down in a diagonal pattern [(x, y, z) -> (x+1, y, z-1)], while seemingly they cannot do so upwards without a ramp being present [(x, y, z) -> (x+1, y, z+1)]. I would assume the reach of building destruction being handled by similar code to digging, thus enabling creatures to reach below, but not upwards. Nov 20, 2018 at 12:39
• Additionally, creatures might be able to climb down Nov 20, 2018 at 12:48