took three attempts to find somewhere the plunge could go
The first plan was the ensuite, which the floor killed fairly quick since a full tub weighs about as much as a small car and those joists were never asked about it. The second was the garage which was fine structure wise but practically miserable bc using it in January meant crossing a yard first. So the obvious answer was outside and I abandoned it once i realised the tub I had picked wasnt build to sit out through a winter which is a decision u make once and live with.
it sits on the ground floor now against an exterior wall and next to a drain so the slab takes the weight without anyone needing to think about it and the run out to the unit stays short. If you are at the planning stage work out where the drain is before u decide anything else bc everything else is negotiable and that isnt.