Hatch cover

A hatch cover (also called a floor hatch or just hatch) is, in effect, a door, but controlling the passage between Z-levels instead of along the same Z-level. They can be placed over stairs or ramps, or open space as long as they are supported by an adjacent floor tile. Hatch covers be constructed at a Mason's workshop, Metalsmith's forge, Carpenter's workshop, or Glass furnace from stone, metal, wood, or glass respectively.

Like doors, they can be linked with mechanisms, or locked, or kept tightly closed to keep out water, pets and foes alike. They can be set as internal, but as rooms cannot occupy multiple Z-levels, this has no effect.

A dwarf falling down stairs will be stopped by a closed floor hatch. A dwarf standing on a floor hatch over stairs will not start falling if the hatch is opened. A dwarf standing on a floor hatch above a ramp or open space will start falling if the hatch is opened. While the falling dwarf may be able to climb to escape injury, he will drop any items he was hauling, possibly injuring dwarves below.

Garbage dumping

If a hatch cover is placed over a hole (natural or channeled), a garbage dump designated on the hatch will cause items to be dumped in a pile on top of the hatch. If the hatch is subsequently opened (by means of a triggered mechanism), the items will fall into the hole. If the hatch is opened at the time of dumping, the items will be thrown directly into the hole.

If a garbage dump is designated next to a hole with a hatch cover on it, the behavior depends on the state of the hatch cover. If the hatch cover is not linked to a mechanism at all, items will be piled on the hatch cover. If the hatch cover is linked and opened, the items will be thrown directly into the hole. If the hatch cover is linked and closed, the items will be piled on the ground (in the garbage dump tile).