Could we ignore that lab itself for a moment?
Sit down with Covenants for a bit, and you will find that it is trivial, but ends up with certain flaws and likely a large number of 'Empty' flaw-instances.
It is not what the OP was originally asking about, but again it is a fairly trivial problem, so no worries.
How did you enchant you lab in the first place? Technically, whatever you enchant must fit inside you lab, at the time of enchantment.
This can be solved in (at least!) 2 ways:
- Ignore that bit, "a Room is obviously inside itself".
- Build a room inside a room. I did this with one character (an NPC), who build a (slightly) smaller wooden room inside his lab, which he then enchanted to turn into stone and change size. Essentially he had a lab he could gather up and put in a pocket, inspired by Skíðblaðnir.
In the first case, there's potentially a problem, one which I would have prefered to avert earlier. You cannot invest a Room, because you must invest a whole item. to invest simply a single Room in a Structure would (to my mind) be akin to investing part of the blade of a sword, ie one edge of a double-edged sword. This I wouldn't allow either.
Mind you, once you have the lab surrounding your Structure, it should be fairly obvius how that part works.
I would echo this.
Sadly, I'm not buying this. The 'Boundary' reference in the Expanded Table is merely a description (and advice on how many extra magnitudes for size you'd need). I suppose it would be relevant if you decided to enchant the dirt inside a give Boundary, but I don't see how enchanting something big suddently allows you to ignore other fundamental rules of devices.
Do you by any chance remember this thread? And within that thread, perhaps this post?