I know it sounds lazy, but in all honesty, I just want to be able to construct large rooms without ugly pillars everywhere. It's partly unrealistic (there are many materials that with proper handling could easily support gigantic roofs) and partly annoying (why should a roof over a 9x9 room dropping kill half my colony). If anyone's in the mood to create this, it is much appreciated.
roofs are hard coded i think
check out the mod
roof support mod in release tab
Just so you know, you can make a room up to 12 wide and infinitely long without it ever collapsing. When you move to 13 wide or bigger is when you have problems.