One thing we discovered when we moved in was that some of the floor joists had rotten away due to a small amount of damp. We discovered this when we removed the carpet and underlay and the corner of the floor was unstable.
I will do a full blog post on what we did but I have been spending this morning fixing new joists to the rotten joists to provide support. I then cleaned all the floor boards and sprayed them with cuprinol to treat wood and kill any dust, small pieces of wood that may cause cross contamination due to wet rot, dry rot and infestation.
The next step is to repair the two damaged floor boards, replace these and then start the job of sanding all the boards in the house followed by staining and protecting the boards.