# Plan and completely build the first floor outer walls.
# Activate a mallet on a tile below and plan floor above
# Plan at least one tile with an opening above to make a ladder for a spot to climb up to upper floors. You can later destroy it and replace with a or plan your staircase if you wish.
# Build the floors from below.
# Use the ladder to get up to upper floor.
# Activate a mallet, right click tile borders to plan walls.