Thanks for the advice.
Infact - the distances are measured from the nails in the existing floor, so I guess this is heart to heart rather than space between.
Thinking about this - the weakpoints will be where the ends meet, and so I could add support in these areas only as a compromise -...
I am about to embark on laying an oak floor in my house. This will be partly on a concrete sub-floor and partly on joists.
Regarding the joist areas, I really wanted to remove the existing floor in the two rooms (nailed pine boards in one room and chipboard in the other) and then secret...