this is my first property i am renovating. i have made the niche so far from stud and the back i have used 12mm plywood and sealed using ob1 sealant/adhesive. I have already purchased some aquapanels to use. would it be best screw the aquapanel in the niche and use the knauf joint adhesive, then waterproof joints/ screws with a tanking kit like mapei waterproofing kit or can anyone recommend a better installation method. tia