Wet room loose tiles and grout failure

[Kitth1]

Advice needed, noticed some grout that was cracked and tiles becoming loose in our en suite wet room (water came up at edges when pressed after use). Was installed around 3-4 years ago at best guess by previous owners. Planned to clear out the grout and re set the loose tiles with new grouting where it had failed.

When I have done this and lifted one out seems to have taken some substrate out as well that I can't identify. Is the black stuff with mesh in the tanking layer? Doesn't look like any of the membranes I have seen on instruction videos. The blueish stuff feels a bit rubbery so wonder if this is the tanking?

Any ideas or have seen this type of system before?

 

[Tiler87]

The dark grey mesh is cement board, it could be a pre sloped cement board shower floor. Is the floor underneath timber or solid screed?

 

[Kitth1]

The dark grey mesh is cement board, it could be a pre sloped cement board shower floor. Is the floor underneath timber or solid screed?

Thanks. It's upstairs so is over a timber floor.

 

[Tiler87]

Thanks. It's upstairs so is over a timber floor.

The grout cracking is usually a sign of movement underneath, unfortunately its hard to pin point the exact problem without removing everything back to the original timber flooring. It could be incorrect installation of the cement board base, inadequate prep of the timber floor before the cement board was installed or just a combination of things. I can't make out clearly from the pictures but is the floor tile cut into the wall tile?

 

[Ben-gee]

The black with mesh is RIW Tilesafe membrane, aka “The Devil’s flypaper “.
This is indeed the waterproofing membrane, which you have now f***ked, it is a bitumen based membrane that has fallen out of favour. It is very effective but quite tricky to work with and therefore outside a lot of tradesmen’s skill level!
You will need to repair the membrane.

But as usual with these things - the wetroom was probably poorly installed and you will be looking at a substantial re-do.

 

[Kitth1]

Thanks for the comments. Just seen that the RIW stuff has been withdrawn from the market so no chance of getting a repair kit. As the tile was loose and pretty firm with the adhesive I think it had probably come a bit loose anyway and I've just made it worse.

I'd actually reset the tile with a good layer of flexible wall and floor adhesive over the full footprint this weekend and was going to re-grout with some decent flexible grout and see if it cracks again. Annoying I have no idea how the installation was done or by whom! Can't see which way the tiles are cut in either as a layer of sealant in reasonable condition around the outside I don't want to remove.

Guessing the best fix is to rip out and start again but might get away with it for a while if the top surface is in good condition as the tanking is the insurance? Aware of risk to joists/floors etc.

What are the thoughts on the pre-waterproofed formers? Might put them in and retile the section it is in with a screen rather than re do the entire room.