Diy bathroom refit

[Cjh95x]

So I’m renovating a house with next to no knowledge, I’m currently doing the bathroom how do I go about doing the joints on this tile backer board so the joints are water resistant?

 

[Topspread16]

I’d be more bothered that you’ve boarded before putting the pipe in the stud. Unless it’s a water feature.

 

[Stewie03]

I’d be more bothered that you’ve boarded before putting the pipe in the stud. Unless it’s a water feature.

It’s gunna be a very high sink instead

 

[Topspread16]

It’s gunna be a very high sink instead

I thought it was a shower just spray it into the aur and let it drip off the ceiling onto your head.