Timber frame wet room

[Defense88]

I am adding an addition to my house that will be timber frame with 6x6 floor joists 1 foot apart because it is being designed as a wet room it can be designed which ever way works best my main thought was can I slope my floor joists down 1.5 inches to get my slope the shower room will be 12x5 with the linear drain at the entrance of the shower the shower room will also have a free standing tub then I wanted to slope the rest of the floor back to the shower drain does anyone see any problems I will run into