How do you prevent a cave in when there's no roof?

[BoxingBud]

A colonist lost her left ear taking down a sole section of wood wall in the middle of nowhere with no roof on top because of a cavein. I literally do not know how to prevent a cave in when there is no ceiling to...cave in.

[Mr W]

By default, every time you build a wall it is roofed. Are you sure there was no roof?

[BoxingBud]

Pretty sure. It was one accidentally built wooden square in a field. Maybe it's the zone? I didn't specifically set any "Build roof" or "Don't build roof" zones.

[Zordah]

Anything more than 6 tiles away from a wall has a chance of collapsing even if you are excavating under a mountain. I think you need to place a single wall piece as a support column so nothing is more than 6 tiles away from a wall piece.

http://rimworldwiki.com/wiki/Roof#Roof

[Kid 1,000]

You can expand no roof area and they construction pawns will take down the roof. I've taken down entire mountains this way.

[BoxingBud]

Dam I never thought to apply this to mountains! Does that guarantee no cave in?

[Dingokeeper]

You can only remove "Constructed Roof" and "Thin Rock Roof" in vanilla. Certain mods exist to let you remove "Overhead Mountain"

You can always check what sort of roof is over tiles by mousing over and reading what the bottom left of the screen says.

[BoxingBud]

Hey thanks for the advice! This helps a lot!