If you're doing a really detailed build this can fudge you up badly, but for the average player who's just snapping a few pieces together and calling it a house.. all of that can be repaired and improved.

Restore your world to a previous backup autosave. I had to do this in one of my 200hr builds im working on, as soon as I took the roof off to adjust it, the rain ruined about 100hr's worth of custom woodwork, many of which were pieces clipped into this and that, couldn't be repaired.

Auto saves are a life saver, just restore your stuff :)