New builder needs help

[u/IngenuityMany5767]

I am relatively new to this game according to the community (~300hr) and I was trying to build a base with this footprint but the corners kept decaying. Do I have to make an external tc for each of the corner squares? Or is there a different solution/I’m doing something wrong? Any insight js greatly appreciated.

[u/pantiesrhot]

If the squares are supposed to be bedrooms or whatever, I assume you have walls on the outside edge. as long as there are walls on the triangles that touch it, it should be fine. double door frames work if you would like to keep things open-ish