I have a very small 63x85" bath off my master bedroom which includes a 32x32" shower which is almost impossible to use.
This house is in Southern NM and was built on a monolithic slab with integral perimeter foundation 30 years ago. the current vanity is along the outside South wall and the sink's 1-1/2"vent stack (PVC) appears to run up that wall directly above the sink.
I am merely in the thinking stage (feasibility investigation) as to whether I could build a bump out to contain a new shower's entire footprint. The shower door would be along where the outside wall with the vent stack is now. Then I would relocate the vanity to where the tiny shower is now. ( I am assuming the could be easily done as far as drain piping.
I'm not familiar with how underslab plumbing is/was constructed and whether I could connect the drain into what is there and vent it properly.
Any thoughts would be appreciated.
I think it is feasible, but there are building codes, electrical codes, and plumbing codes that have to be considered. Many of these things must be decided on site, so I think the first step would be to hire either a building contractor to evaluate your general idea and make specific suggestions on what can or can not be done as well as how deep your pockets will have to be. I do not see this as a wise DIY project.