retirement home for two people who is getting up there in age
This is (mostly) all toilet related:
The day of our first date, my wife closed on a 1052sqft house. It is a 3bd, 1ba ranch on a slab. (emphasis on slab/no basement) I proceeded to fall head over heels for her, then I shacked up with her, and then I systematically destroyed her house. I gutted it one room at a time and re-wired, insulated, replaced windows, re-hung drywall, etc. (pulled up the nasty/bad floor tiles) I literally nuked each room down to the studs and re-wired.
I also re-piped the heating system, I rewired the whole house, I re-piped, re-ran and re-located a bunch of the air/hvac stuff, etc. At the time, my thought was that we had dogs, wanted kids: So make it bulletproof... and then rent it. Someday maybe we'll move back here when we get old. And also her dad lived alone so worst case we could put him here if we needed to.
Fast forward to now: We are still here. But actually not for long. Her dad is sick and he will be here soon.
Not toilet related: The prior owners had some hack install the central air. The installer cut a bunch of roof joists/collar ties to shove the AC return (I honestly have no clue why he put it there...) That cracked a bunch of drywall which is part of the reason why I nuked each room down to the studs. During that ceiling joist repair, I reinforced the ceiling in one of the bedrooms to make it load bearing. So we could have a s3x swing or something... Seriously: So we could put a lift in the room one day if we ever needed to put a hospital bed in that room. Just something to think about: You said "drying in". Maybe it's not too late to think about stuff like that.
I also went through every doorway and opening in the house and made everything ADA compliant. It wasn't that much extra work.
The bathroom was the hardest part: Because it is a 1052sqft house built in 1954. We did the best we could. The shower/tub is the only part of the house that is not ADA compliant. We weren't willing to take that much space away from the master bedroom, and the way that the hallway/doors are: It would have been a LOT of work, and engineered LVL's, and a royal pain in my rear-end.
If you read all that, I basically have two suggestions: Look at USA ADA compliance guides. They lay everything out pretty well in terms of spacing and placement for stuff (toilets, sinks, showers/tubs, etc.)
#2 would be that I put an electric outlet behind the toilet. My wife thought I was crazy and she even fought me on it. I thought that one day maybe my sweetheart might want a heated toilet seat to warm that beautiful part of her body that I love... And screw it: Wire is cheap when the walls are blown out...
Never in a million years did we ever expect her father to get cancer, and for his chemo meds to cause nephropathy (which includes cold sensitivity). So that stupid dedicated 20A circuit I put behind the toilet (unfortunately) paid off. But think about it. A receptacle behind the toilet is a pain in the rear end to add later...
Oh! I forgot...
#3 wall blocking!
PUT BLOCKING IN THE WALLS BETWEEN THE STUDS! Read the ADA manuals, etc. and see where they suggest to put hand grabs, railings, etc. Leave enough room around your toilet so you can go in from the front on a wheelchair if you need. And put enough blocking in the walls so that you can put hand grabs and railings... Basically everywhere. You just cut (I used 2x6 and 2x8) sections and nail them between the studs, and then you take LOTS of pictures, so that when you actually need to put in a hand railing, you can reference back to your photos, as well as any ADA manual/guide/documents. And all the locations/heights will be documented via your US tax dollars.
Look for a toilet that is ADA compliant. I have another friend who's mother just fell and broke her femur+hip. He text me today (looking for help and saying) that he is shopping for a toilet that is "wheelchair height".
Best!