Some advice please on replacing part of wall

[Cosmo]

Hello, Cosmo here and have been surfing on the forum. Thanks for all your help and now I am facing another tiling problem and hope someone can advise.

When we were taking the old tiles off just above the front of the bath tub for retiling one section of the plasterboard got stuck on back of old tiles. We took it off. We now clear the damaged plasterboard area (around 1m sq) but thought we should go for something waterproof. What should we use (the original plasterboard was 12mm thick I think). Here are my questions:

1) Someone recommended hardiback. Is it the best to use? Is it very different than waterproof plasterboard? Where can I get reasonable quality at good price?

2) To cut it to fit the area (square in shape), What are best to use e.g. angle grinder etc?

3) The wall behind is made of concrete. What is the best way to fix the plasterboard on the wall?

4) Once that is done we will have to push the hard water pipe into the new wall and tile over. We will cut a channel to fix the water pipe (of the electric shower) in. Before tiling over, should I use plasterboard joint tape to seal the area?

Hope to hear from someone soon. Cheers.

Cosmo

[whitebeam]

I would just replace with 12.5mm plasterboard and dabbed on with dry wall adhesive, then tank the shower area

[aph257]

as above for me.

[timeless john]

Already PM'd you!