A little bit late, but here we are!
The hot of the radiator hoses and the cold wall (exposed on north) created moisture that was soaked by the plaster, and then brought to the wooden floor.
The wooden floor was also covered with a fitted carpet.
And the edges were completely rotten!
This is how I fixed the moisture problem that affected the edges of the floor.
A picture is worth a thousand words.
shaving a beech wooden floor with my japanese planer..
love this photo.