We are in the process of interviewing several potential contractors. After these screening interviews, we will ask for bids from the 2 or 3 contractors who are most knowledgeable and compatible with us and our project. We know what we want for most parts of this bathroom, but we are still trying to understand the best way to design an accessible shower. We want to add it now as we rework our main floor so that we can eventually "age in place". The four contractors we have spoken to so far have looked at the joists, sub-floor and open access from below; and all confirm that we can readily recess the floor under the shower. They differ, however, in how they would handle the shower pan and drain for this curbless accessible shower. A couple of them have suggested the Wedi system with a linear drain. Another talked about the Schluter system, and a fourth contractor said his tile man only does a traditional mud base with a central drain. They all said that floor in the main part of the bathroom could be level and the sloping would all occur within the 4' x 4' shower (1/4" per foot). Most would put waterproofing under the whole floor, but one typically extends the waterproofing just a foot or two beyond the shower entrance. Are there reasons to go with the traditional mud base vs the Wedi (or other foam type backer)?

Well, I know how you feel there. But you will be tying up access to your closet if another person (not your partner) is using the john or taking a shower. If I read your room use correctly, you have half baths in attic and basement, but no other bathing facilities? Just in this area. IF you split this you could make a secondary toilet/vanity area which could also be entitled to use the shower. But you could still lock off their access to YOUR master bath and closet area. I think that MongoCT drew something like that. And technically, if there is no closet directly associated with the main bedroom, it technically cannot be called a bedroom. I understand what Terriks means about that. Even a small closet can keep it designated as a bedroom, but it would be hard to call it a "master suite." In my DH's house in Mass, I've been dealing with a similar problem, so I know how mind boggling it gets. On the main floor of the house, a cape, we have a full bath with a tub. It serves as a guest powder room. I am adding a master bath adjacent to it, but this bath only has room for a shower. So what I'm doing is making it possible for us to combine the two when we are at home with no guests. And when we have overnight guests upstairs, we can also lock the door from the living room which gives access via a tiny hall to this full bath. OR, conversely, I have a door further down the hall which is really the bedroom back door(another one exists)---it blocks off access to our bedroom from this direction, as well as to the 3/4 master bath. By making all the flooring the same in the full bath, the tiny hall, and the 3/4 master bath, it will I'm thinking look cohesive. I'll have to try to put this drawing up for you. It is much simpler than your plans, because our walkin closet access is separate from the bath areas. I'll have to go back and view your current setup for the plumbing etc, to see if your dream of a big bath can be achieved while keeping the walkin closet dedicated to your bedroom.

Is your father in a wheel chair or are you anticipating the need? I ask because I have some experience dealing with elderly parents, their friends as well as some very senior neighbors. In my experience most seniors are not in wheelchairs except when they need to go a long distance. In other words, as long as they have a 24/7 caretaker by their side, they are using a walker to get around inside their homes. Also they are capable of stepping over a low curb with assistance for balance. As others have posted, it might make more sense for you to use your master bath for bathing your parents and turn the powder room into a toilet and sink area since accessibility to the toilet is far more important than a shower - e.g. when my father was in the last year of his life with a 24/7 caretaker, he had to urinate frequently versus taking a shower. While a senior can't easily walk over a tub/shower combination, there are actually seats that swivel and so a caretaker can get a person into a tub and then shower him/her with a hand held attachment. The other alternative is to turn the tub/shower in your master into a nice shower which you will then enjoy. I recently remodeled my condo with an eye to aging in place. There was certain stuff I couldn't do but such as enlarge the bathroom but I swapped out the tub/shower for a larger shower with a lower curb and grab bars at the entrance and along the long side. I also had a bench installed with its own hand held next to the shower so either I or my caretaker can hose me down while I am sitting if it comes to that LOL. Although my bathroom is relatively narrow, I can use a walker to get to the toilet and swing the walker around once I am at the toilet. I tested that with a neighbor's walker. I did also install a grab bar by the toilet and also a Toto washlet. The washlet is actually an aging in place accessory as I have friends who became unable to wipe themselves easily because of hip or shoulder issues or even arthritic hands.

Adding Warmboard is a big deetail as its nearly 1" in elevation it can change run and rise and effect other details, so im sure your architect and builder have educated you on that vs wired radiant? Weve used radiant and hydronic both in this scenario, If you are having a whole floor hydronic and you have a properly recessed pan area it can be done. W either approach id need to have the whole build spec to make these decisions in my approach. I prefer concrete pans w a thermal break, topical waterproofing and radiant heat just below tile in a shower build to make my decisions on how id do it would require more details. Lean on and trust in the professionals youve hired, surely youve made smart hiring decisions if your concerned about these type details.