SB: How about I build you a staircase?
PI: sure
SB: Awesome! I'll get to work on it now. Y>Y
You go to the outside of Meowrage's house and hit the staircase option on your construction cursor.
The staircase up to the next floor is built. It costs 25 blue SHALE GRIST. Luckily, your compatriot has collected over 100 by this point. You suppose it should take a lot more grist than you have to fully make it to the FIRST GATE, and the SEVENTH is way out of the question. For now, you just finish the newly made upper floor.