What a man-cave! I know many that would be very jelous.

I bet you, you could JUMP up and down on it and be completely fine. Its the same stuff or very similar to mine which is literally as strong as an ox! still think you will eventually end up going back to it this job taking the sheets off, boarding and felting. then re-fitting them.. you sure there is no run-off? your neighbours looks like its sloped!. even if its not you could just re-do the joists?