When you build stairs and roofs it creates a partial triangular-like wall that does not extend past the top of the stairs/roof. Is there a way to take a section of roof that has had the wall previously removed, and place a partial wall there? I know if you remove the roof and build it back again it will create the wall. I was hoping there was another way as roofs are soo hard to manipulate, and deleting the roof to put it back in for some reason screws everything else up... Many thanks =)

Moved to Building forum

Oops, my bad haha.

No, it's really annoying. I have spent days trying to find a way to add the extra walltypes so you can pick them from the buildmode interface - in theory it should be doable, but in practice I just can't get them pickable by the player You just have to rebuild that bit of roof.

I'm not sure what you're talking about. Do you have a picture of this triangle.

Inge already solved the OP's issue, so there is no need for pictures. Currently the only solution is to replace the roof.