I liked the appeal to the senses reminds me of the bat in my attic; sometimes it finds it's way between the plaster and lath walls. I think sinking in like a dream is fine. Often we forget dreams when waking they don't seem to penetrate the spaces in our brains that allow us recollection. However to me it seemed to describe more of sinking into dreams slipping into sleep. The way we transition from control to lack there of. I liked it.
Simple and gorgeous. The rhymitic sound of the falling roof ("Tip, tapping. Crick, cracking") was brilliant. (And a technique I recognise in my own stuff)
This was so short yet so brilliant and the cliff hanger was very interesting. And you manage to show fear through the fact the narrator seemed stunned to the point of not moving.
The only thing I question is it the ceiling sinking down like a "dream". I just feel you could come up with something much more interesting than 'dream' - a common theme for poems.