Removed last bit of grout and tile popped off, pb wall behind is gubbed

[Colliwobbles]

Hello all. Due to water staining to the wall in my bedroom adjacent to the shower in my en suite, I removed the defective grout (and a lot more, basically to head height). As I was chasing the grout out the very last bit one of the bottom tiles popped off, revealing the (what I assume to be) plasterboard that is pretty gubbed, presumably due to the previously defective grout.

What's the best way to prepare the wall to refix the tile? The gypsum is cracked and crumbling. A mate suggested using expanding foam then levelling and refixing using Stixall or similar. Is there a better way? or could I fix a wet wall panel to one surface only?

Upper floor flat in 2007 timber framed building.

 

[Burnerman]

Looking at that I'd be very surprised if most of those tiles in that area were ready to pop off.....The tiles really need to come off until dry material is found, the plasterboard replaced with aquapanel (cement board) and the tiles replaced. Sadly you don't want to cover that lot up - it'll come back to haunt.
John

 

[Colliwobbles]

Thanks Burnerman. That was my fear . So remove all tiles, remove plasterboard, install aquapanel in its place? Presumably I could then fix shower panels/wet wall sheets on to the aquapanel? I never want to see another grout line in my life....

 

[Burnerman]

Yep, to make a good job that's about it I'm afraid....maybe more work than you wanted
Wickes aquapanel does not resist water of course but it doesn't deteriorate like plasterboard - which is a ridiculous medium for use in showers!
A great surface for showers is MultiPanel, and worth looking at - but either way you'll need access to the shower valve.
John

 

[Colliwobbles]

Thanks again Burnerman

So:

- remove all tiles
- cut out any plaster board that is rotten (or is it worthwhile just removing it all - aquapanel not that expensive?)
- replace rotten plasterboard with aquapanel
- fit multipanel or similar

Presumably I need a joiner to fit the aquapanel and a tiler to fit the multipanel (or similar)?

 

[Burnerman]

Yes, that's about it really - aquapanel is cheap enough and is a good backing to fix the multipanel to.
Due to the hideous cost of MultiPanel, only bash on yourself if you feel competent - the corners fix with anodised aluminium both internally and externally but you do have to get it right - it sits on to the shower tray with a silicone bead.
The instructions are thorough and must be followed to the letter.
Other alternatives are cheaper - someone mentioned Mermaid board but multipanel is the only one I've used.
John