Originally posted by Cap'n Bells:

digging under existing building may change the viability of roof.. use hammer and "look" at foundations "look" at them all they should progress from blue to green to orange then red as you "look" / get higher up the structure.. whichever piece of roof is collapsing will help you see which corner below it to check!

Thanks for that, and yes I was doing it - which is why it was driving me mad. lol

It's still stable. I filled in the cavity a little under the house, especially around foundations and everything is holding up.

Thanks again everyone