Shower room problem

[MikeJJ]

I have an en-suite shower room on my first floor (suspended wooden floorboards)
The shower room has a 'stone' tray and is fully tiled. The problem is that it is prone to leaks. I have in the past raked out the existing grout and replaced with 'waterproof' silicone grout, resealed around the shower tray etc etc. The final straw was when the tray actually cracked around the waste outlet. Water through downstairs ceiling - lots of mess - very irate OH
I suspect that the walls were not properly tanked before the original (DIY) work was done. I plan to replace the shower tray - probably with a wet room former, tank the walls and retile floor and wall.
My question is - could I tank over the existing tiles and the retile over them? I know ideally I should strip right back and start over but the removing the existing tiles will be a time consuming and very arduous job which I'd like to avoid if possible.

 

[AdamCH]

Strip it back and do the subfloor prep properly.

 

[ree]

As above. Why did you have tile over a stone? Are you saying that the stone tray was cracked or damaged?

When you've removed all the tile, & the tray and any floor tile, post pics of what you have left, & be advised further.

Sounds like there's a chance of the floor below the tray being water damaged?
Are any of the wet walls stud walls?

 

[MikeJJ]

Thanks for the prompt responses.

The 'stone' tray is a reconstituted stone tray and it has a hairline crack.
The existing wooden floor looked in OK condition when inspected from below prior to re-plastering the downstairs ceiling. The leak was not catastrophic but had accumulated, unseen, a pool of water above the ceiling over a period until the ceiling could take no more

I am planning on removing the shower tray and redoing all the sub-floor to include a slightly raised platform to accommodate the waste. The platform would be of aguaboard or similar and I was going to put a wet room former on this platform. Then I am going to tank the former + wall to at least 6' - ensuring a tanked and watertight seal.
My question is about the walls (which are currently dry but tiled over marine-ply boarding tacked to the existing wall) - 2 of which are plastered blockwork and 2 are stud walls.
My original question was - since these walls are in good condition - is it possible to use tanking mastic over the tiles and then retile over the tanking so avoiding having to remove the tiles which will inevitably damage the walls and therefore will need to be relined? Lots of mess, time and cost which I could do without.

 

[ree]

No. You would bring yourself grief. It wont work. I'm telling you how i would prep a job for money - no risks.

Personally, i wouldn't tile over ply - only over sand & cement render or backer board.

I know next to nothing about formers , i've never used one but i believe that you can source them with upstand fins - just like some regular shower trays.

 

[AdamCH]

If you raise a wet room former above the surrounding floor level then you may get issues with water escaping from the shower area. It's usually better to fit them flush or even slightly lower with a lip to keep the water in.

Strip the tiles off the walls and throw the ply away or over board it with tile backer boards & tank the whole lot unless you use a waterproof system like Marmox or Wedi etc.

 

[MikeJJ]

Thanks for the advice, I've made a start on stripping the walls back

I'm surprised that marine ply is not recommended after all they build boats with it

I am looking at ordering a bespoke one of these:-
[/url]http://www.tilefixdirect.com/BespokeShowerTrays and using homelux matting with .... Any views on these selections? Mike J