Originally posted by DeGreZet:

Ok so it is +20 elements tower, placed on stone ground and walls, with beams all around it + in the middle, supporting almost every floor inside. Can't build roof which is also supported, because parts below it changing colours from greed to red.

+20 elements doesnt explain things.

That said, it sounds like you've built too high without proper structural support. As electric said, you're going to most likely need to build with iron beams but even then you may have issues depending on your design.