Upward stairway

From Dwarf Fortress Wiki

This will carve an up stair into a wall. Unlike a downward stairway, this cannot be designated on a floor. If no wall is present it can be built using the build interface (bCu).

Carving upward stairs

1. Press d to open the designate menu.
2. Press u to select "Upward Stairway".
3. Move the cursor to a position on or near a wall and press enter.
4. The spot you marked blinks + indicating where the area you wish to start carving stairs.
5. Move the cursor to any position across the area you wish to carve upward stairs and then press enter again. This area must be a non-built wall. Any area of floor or construction will not be selected. Usually, this is just a single tile.
6. The wall tiles in the area you defined should blink similar to mining.
7. Wait for a dwarf to do the job. For each upward stairway, you will need to designate/build a down stair or up/down stair on the z-level above.

Building upward stairs

1. Press b to open the building menu.
2. Press C.
3. Press u to select "Upward Stairway".
4. Move the cursor to a position on a floor or accessable open space and press enter.
5. Select a building material from the list (the higher up on the list, the closer the material is to the stairs) and press enter again.
6. Wait for a mason to do the job. For each upward stairway, you will need to designate/build a down stair or up/down stair on the z-level above.