2.3m is the total length including the stairwell so should be OK -
cheers
for doing the calcs! :-)

If you have the demo of superbeam there, then you could model all of the
joists. You may find that you can simply add the new joists without
needing major rework on the existing ones.

... in fact ... ok just did it. (usual caveats apply)

It looks like you could leave Joist B as is, since it is not that
heavily loaded (I am assuming its length is about 2m based on your
diagram). Over the stairwell you could add some 175x50 joists (approx 1m
long?) hung between the wall and B, and B will still be in spec.

This leaves A, which is now carrying extra load at the point where B
joins it. That is now right on the limit with regard bending (if you
also assume it is carrying a bit of floor load - which in reality it may
or may not be carrying, due to its proximity to the concrete beside it).
If one were to stick another 175x65 joist (or narrower if you want)
beside it and bolt it to it, then you would be well in spec on that.

Woohoo! Cheers John. :-)

As I say, I loaded SuperBeam up. Looked through various screens. Got
frightened. Closed it again. (Sorry Tony! :-) )
Hold on...
Yup, tried it again and the same thing happened! :-(

I'll see how the ground lies once I've managed to rip the partition wall
down between the stairwell and existing bathroom... and also lifted the
boards where the bath is etc. It *might* be possible to bolt A to the
concrete (along with another joist or even some steel), not sure until I do
a bit more demolition though. BTW, yes - joist B is 2140mm and the
stairwell is 910mm wide.

Ta!

Andy