Cave ins

[CakeOP101]

So I built a mountain base (for like the first time in 70 hours, I never play mountains). I got a cave in. I built a nice room where the cave-in rocks were still there. I decided to destroy those, thinking the walls provided enough support. They didn't. My 2 colonists, a miner and a person who was a fiancé with my farmer, died. My farmer went berserk twice, although he is still living. And then as soon as those 2 died, a raid came. Now my top builder has no jaw. Rip

[Wex]

If I am correct, the maximum space between 2 supports is 12 squares.
Build support columns!