Replacing old floorboards

[pertinky]

Hey guys...120 year old house but I suspect floorboards to be about 60 years old. In process of rejigging the bathroom

Ive just had the mega flo moved to accommodate an ensuite and its left me with a few broken and loose floorboards. Ill be taking up a few more to run the new pipework for the ensuite and need to put up a new stud wall either side of the room so im at odds now with whether or not to replace the entire subfloor while its like this.

The boards ive taken up felt very dry and brittle but the rest of the upstairs has had all the boards replaced with french oak. I am planning on tiling.

There is a small stud which runs over the boards so I hoping I could slide a new subfloor underneath carefully when it came to it

My thoughts were to get some 22mm ply then pop some hardibacker or similar down for tiling. Joists are not quite 400mm...more like 420mm with a few newer joists in between.

 

[pertinky]

Closer inspection reveals some historic woodworm at the very least, few boards particularly bad at the edges of a few boards so I think it'll be best to take them all up

The new joists (circa 17 years old) look to be free of any woodworm evidence so its unlikely there is a current infestation or there would be holes in these too.