> A plumber isn’t going to refuse adding another bathroom to your house, they’re going to tell you how it can be done and tell you the cost
Let me know how the plumber reacts when you then tell him said bathroom needs to be freestanding 300m in the air, and the plumbing needs to be made out painted twigs and twine (because your housemate thinks they look pretty), and you also want heated stone floors and you have a budget of $250 and an ice-cream wrapper.
In the miraculous case said plumber accepts the job, make sure to change specs halfway through.