Utilising void above staircase

Hi all,

I want to extend my bathroom into the head space above the staircase. The space will be used to incorporate a new sink and shelving above. The problem however is that anyone who is 6ft+ has to duck slightly when going up and down the stairs to avoid the existing ceiling.

It's not practical to run a framework along the landing and up to the ceiling and this will only limit the headroom further.

Can someone suggest a smart way to attach a new framework to the existing so that it will be able to bear a load (sink & tiles) whilst not impacting clearance height?

As you look at the existing wall to be extended (which is lath and plaster); to the left is an existing lath and plaster bedroom wall, to the right is the banister with landing and above is a plastered ceiling. Pictures attached.

Thanks for your help!

 

No room for a corner basin as space is at a premium The bathroom will measure 170cmx170cm so need to reclaim storage space where possible.

 

Thanks for the suggestion Wiggy. Do you not think the spindles being cut at various heights to accommodate the 45degree will look a little carp?

Would it be possible to reinforce the framework with 45 degree angles inside where the perpendicular angle occurs?

 

KoolPC - that'd be better than the shower installed in there at present!

Wiggy - thanks for your help. Appreciate it.

 

KoolPC - already done that...

HandyAndy - Pity there's a bedroom off to the right of the landing. The suggested position of your new door would effectively box the door off! Should have mentioned, apologies.

With that in mind, would you still advocate Wiggy's suggestion, minus the filling in?

 

Thanks for everyone's input. Still undecided but think I'll square it off.