Thanks, Tom. I'm in the demo stages on the old bathroom/laundry room area but I have a lot of projects on my list. I still need to repair the botched floor job in my bathroom and I would like to replace the tub surround and go from 3 knobs (hot, cold, diverter) to a single lever while still keeping my old cast iron tub-- but the tub/shower upgrade there is low priority. Highest priority is getting the floor in there good enough that I can tape down my sheet vinyl and install the toilet. I've got the toilet in a box ready to go in.
Once I have a usable toilet in that bathroom, it will be easier to move on to tearing out the fugly avocado green one piece fiberglass tub/shower unit that must have been put in before the doorways were built (bc that thing won't fit through the 24" door). I'll need to put in a shower with grab bars for her and tear the floor out down to the joists to replace it with a good sturdy subfloor and install the sheet vinyl that is rolled up in her bedroom.
I'm still debating whether to do her bathroom first or fix the laundry room. Because having the laundry room fixed up will make things so much easier. Right now we have to go through a 34" hallway and around a corner into a very cramped space where the floor is all messed up and we bump in to the wall when loading and unloading the machines. In the old bathroom the toilet is crammed in a 23" alcove so no one can use it (plus the fill valve messed up on the toilet), shower doesn't even have a P-trap & is not usable, and it's just a bad setup.
I have to tear out 2 non-loadbearing walls, replace the subfloor/substrate down to the joists, raise & straighten the header for the exterior door, bump the doorway to the new bathroom over a few inches so the door will have room to swing in without the knob hitting the wall, rough in plumbing and electrical, buy & installs some sort of flooring (either vinyl plank or sheet vinyl), move washer & dryer in to old bathroom, get a new toilet and shower/tub unit for the new bathroom, etc. I know I'll use sheet vinyl in the bathroom. The bathroom is lower priority than the laundry room though. The good news is, at least some of the plumbing is already in place. I can bump over the water supply lines from the old lavatory to work for the washing machine, I can bump over water supply lines from the old washing machine position for the tub/shower, and the water supply lines are pretty much already in place for the new lavatory. I can cut off and extend the old toilet supply line to have it feed the new toilet line-- it's just a matter of tying in to the old stuff. It's all PVC for the cold and CPVC for the hot. I'm thinking of using PEX to replace at least some of it. I've always worked with PVC & CPVC, but I have a friend who has worked with PEX.
Man, I'm babbling away. LOL. I looked up the check valves and I saw a kind that uses a solvent weld and another kind that has threads. If they aren't prone to failure, I'd probably go with the solvent weld kind. Can they be installed for toilet supply lines? I want to add a shattaf to the toilet supply line, but don't want to risk any backflow. Frodo suggested some atmospheric thing (can't remember what it was called now) but I think something inline would be much easier.