That bears an uncanny resemblence to the 'notch' I have, although somewhat neater.
Is the remdial work suggested above still appropriate/adequate for this problem now you see a photo?
The previous occupier of my house wasn't too clever. He or she has roughly cut a section approx 7 inches wide and 75% through a joist in kitchen ceiling/bathroom floor. It's starts about 10 inches away from the wall and is right where I'm planning to put the bath....
I'm thinking of squaring...