Eeeek Advice appreciated please

[benchwarmer]

Thank you so much for your advice, it's very helpful.

Yes, floor is sound and dry.

Its not plasterboard behind the tray. Thats a plaster skim over older plaster when the house was renovated about 14 years ago. I've pulled/scraped off any loose or soggy plaster. Its been exposed for a few weeks now and what is there in the pic is solid.

I'm planning on a 6mm waterproof board (like Delta), on a full adhesive bed and mechanically fixed. Joints sealed with aquaseal (or similar waterproof tape).
I thought that cement board should still be tanked as its water resistant but not water proof. Is that correct? If so, I don't see the point of putting up cement board and tanking when waterproof board is easier to cut and doesn't need tanking.
Happy to be told any flaws in my thinking though!

Thanks for the info about siliconing the tray to the board. I didn't know that and it doesn't look like it was done before. There is a 2mm gap between the tray and wall I can see up through the ceiling now I've removed the normal Silicon from around the tray.

With the extra thickness of the board on top of the plaster, the board will probably overhang the tray by 2-3mm. Some earlier poster seemed to imply that wouldn't be a problem as I have plenty of tray. If aquaseal tanked the transition between board and tray, with tiles and Silicon to go on top of that is that going to be a timebomb?

Hi - Thanks, yes I've found it was the grout.
Process of elimination over months, and removing some of the ceiling below. I can see the water is dripping down through the plaster.
Using waterproof tape and plastic sheet over the tiles on that wall stopped the leak instantly. So not water pipes, the shower itself, the waste or the Silicon seal. All these have been discounted.
No cracks in the tiles either.
Even though the grout looked ok and is really hard, once the tiles have bene removed the damp patches have correlated with the grout lines.
So by tanking the wall and fixing new tiles and grout (kerakoll fugabella) I'm counting on that fixing the issue. Unless you have any other suggestions I don't see what else there could be?

The existing wall is old horsehair plaster,covered in a skim coat which hasn't taken, because it's cracked and nackered, anything else you put over it will not be any good!

 

[DangerMouse]

hmmm ok. I see some fine cracks in the old plaster, but the new skim was about 1mm thick. I'm going to be overboarding with waterproof backerboard anyway, priming the existing wall and mechanically fixing.

I'm not an expert so am in no way arguing, but aside from those hairline cracks the only bits that are a bit messy is where the tiles have been pulled off.

Are you suggesting ripping off the old plaster too (which is solid) what if I find some light cracks in the bricks/mortar underneath? Rip that side of the house down?

I don't get how the plaster is knackered? I think the problem was whoever skimmed it didn't do a good job. Why would whatever gets put over it be no good?

Again not arguing, but I honestly cannot see why the old solid plaster is a problem here, especially if it's being overboarded. From taking of the tiles it seems like the tiling, although it looked good, was not great. (no tanking and what looks like only 40% adhesive coverage between tile and wall)

 

[benchwarmer]

hmmm ok. I see some fine cracks in the old plaster, but the new skim was about 1mm thick. I'm going to be overboarding with waterproof backerboard anyway, priming the existing wall and mechanically fixing.

I'm not an expert so am in no way arguing, but aside from those hairline cracks the only bits that are a bit messy is where the tiles have been pulled off.

Are you suggesting ripping off the old plaster too (which is solid) what if I find some light cracks in the bricks/mortar underneath? Rip that side of the house down?

I don't get how the plaster is knackered? I think the problem was whoever skimmed it didn't do a good job. Why would whatever gets put over it be no good?

Again not arguing, but I honestly cannot see why the old solid plaster is a problem here, especially if it's being overboarded. From taking of the tiles it seems like the tiling, although it looked good, was not great. (no tanking and what looks like only 40% adhesive coverage between tile and wall)

Because your old solid plaster isn't solid!? If you over board and fix into the brickwork then you should be good to go, if you over board and fix into your current "solid" plaster then you will have problems, as your "solid", plaster isn't solid because it's cracked to ****!?
If you stick a 6 mm wedi on, then drill and plug, you're fucked horse hair plaster is a half inch deep, it means you're mechanical fixing will be no where near getting a good hold?