Tiling shower wall

Hi Im about to tile a shower wall .. I have used Aqua board from Wicks, The adhesive I have is Bal Ctf3 do I need to use an additive? I will also do some tiling in the dry area of the bathroom but only as a splashback same question. The tiles are ceramic 500x250. lastly I have set out the tiles horizontally and the boarder is 40mmx 500 Passes through the center of the shower valve and the joint is also in-line with the windowsill so should look good, and help with cutting out the correct shape for the valve as it can be from 2 tiles .. the only problem is I have a small cut tile at the ceiling height 20mm ish will this look silly? the shower cubical is 1200w x 800d. thanks

Aqua board is very much like MR plasterboard, which I wouldn't use in a wet area unless it is tanked.

Definitely need to stick with cement based adhesive on that size tile.
Provided the boards are securely fixed, you shouldn't need the Additive, but would need to prime the walls before tiling. Use BAL Prime APD

A cut of less than an inch near the ceiling is not going to look professional, have a look at the tiling sticky for more detailed advice on how to set out your tiles to give the best finish.

K

Thanks for the advice, I bought the Aquapanel because it had a sticker on it saying for use in wet and humid areas grrr wsnt cheap or light lol ... I will get the ADP later in the week .. I think I should have just replaced the old plaster board with umm plasterboard cos I think the cement board was about £18 ish for 1200x900.. but its done now.

I will replan the tiling .. shame though as the boarder would have gone through the valve trim.

Mike