This is the Blueprint prior to placing it.
http://images.akamai.steamusercontent.com/ugc/433823760626906876/0B3A134F761C246220304E8CC42355188EF25EC7/
This is what happens when I place it.
http://images.akamai.steamusercontent.com/ugc/433823760626907744/5546051DCD9A055CC8DFA1E363FD66FF25886458/
Yes, it is within walls at the moment, but I did try a new place, and placed it just in an open field and it also exploded.
It is made of 3 walls, with a free tool created roof.