Cracking grout

[Craig66]

Hello I am new to this site and I joined with the hope that someone will be able to give me some good advice?
I have recently had a loft extension with an en-suite. In the en-suite i have a shower cubicle which is tiled with flexible adhesive and grout straight onto ply and I have suffered the grout cracking twice in pretty much the same place from tray to ceiling.Was using ply correct? obviously the loft will suffer from movement is this why it is cracking? I would be very grateful if anyone could offer any suggestions.
Craig

 

[nuno bruno]

Hi Craig! Try to use flexi grout :8:

 

[brian c]

:welcome:TO TF.

Why did you use plywood in a shower area?did you use a water membrane to protect(tank)the ply?

One reason could be that it is on a joint between two pieces of ply but i think the main reason is that the ply is getting wet and expanding and contracting this causing the grout to crack.The grout might ton be drying out at all if the ply is soaking wet.What was the ply fixed to?timber?

 

[Craig66]

The builder put up the ply and i pva sealed it before tiling it.

 

[nuno bruno]

:welcome:TO TF.

Why did you use plywood in a shower area?did you use a water membrane to protect(tank)the ply?


Always use the membrane in wet room if the walls,floor is are other then cement

 

[brian c]

pva..well thats a no no for starters.

http://www.tilersforums.com/tile-ad...-p-v-versus-primers.html?highlight=pva+primer

 

[kilty55]

hi craig,there was another post yesterday where tiles had crackes on ply in a showerroom and i have also seen this personally,,really ply has no place in shower areas imo and sounds like brian says that movement/expansion of the ply is breaking your grout mate

 

[Craig66]

Thanks to you both for your input on this matter.
It looks like I have committed the cardinal sin by using both ply and pva.
Would you suggest that the ply is removed and replaced and if so with what?
or can I salvage what I have got ?

 

[nuno bruno]

In france we use to fix wall tiles in "green placo" (plasterboard water proof) but anyway I apply a primer and then a painting membrane,once dry is like rubber and it work's!
Here we have mapei too but i prefer weber & broutin!:8:

 

[faithhealer]

The news you don't want to hear Craig is that it wants starting again but if you can't afford it then you are going to have to limp along regrouting every month or so. Sorry