I am a an ex joiner so this might be a stupid question Isn't possible to do some sort of compromise and machine out 50mm from some joists(wher the tray goes) and lower the shower tray into the floor? Not completely flush..something between normal and wet room layout?
I wouldnt as it weakens the joists also i always try to think " what if" if the tray is damaged its hard enough to replace. Mind you i did have to do this once to fit a wet room former ( a preformed tray with waste you tile over to give the proper grading for water flow ) it involved reinforcing the existing joists and flooring but was ok.
Google wet room former to see what i mean. The former needs bedded in something like dunlop large formate adhesive over its entire area then properly tanked then tiled professionally....its dearer than a shower tray and must be done right...preperation is the key along with adequate support as any movememt is failure.
if I'm asked to do one I just pass the job along to the Internet.....really not interested too much hassle
You can get some pretty cool shower trays these days https://merlynshowering.com/range/truestone-trays/ About to start our upstairs bathroom to - in the eaves of a 200 year old hovel Here’s a before pic -
