Shower tiles cracked grout

Dave82

The bottom row of tiles in my shower had failed grout and was allowing water to leak into the room below.
I raked out all the grout and removed the tiles as the adhesive had failed. I then cleaned and primed the plaster, cleaned and re-fixed the tiles then re-grouted. 
All was ok for about a month the grout has failed again and the tiles move slightly if I press them and I am guessing it is only a matter of time before water starts coming through below! 

I think the issue may be that the tiling lip on the shower tray means the tiles need 8-10mm of adhesive. I am a novice to this and used a premixed BAL Greenstar adhesive that shouldn't be used to this thickness. 

Does anyone have an adhesive recommendation that is ok for a bed of 10mm? Or would I be better to get some 4mm backing board and attach this to the wall first?
Thanks
Dave

Belenus

I won't comment on the tile adhesive but you need to use silicone and not grout between the bottom of the tiles and the shower tray.

Silicone is flexible, grout isn't.

Dow silicone 785 is widely recommended but there are many alternatives.

Get one with mould resistance.

Dave82

Hi Belenus thanks I have siliconed between the tray and the tile it's a very thin white bead so is hard to see in the picture. That isn't the issue I am having. The issue is the grout between the bottom and second bottom row of tiles has cracked and the adhisive seems to have failed. I need some advice on what adhesive to use where the bed needs to be 8-10mm 

Le_Kirk

Seems like the shower tray is moving when people stand in it.  I know with a bath, one is advised to fill it with water before completing the tiling, not sure how you do it with a shower tray.

twopenny

There's quite a chunk of silicone around the base of my shower tiles and the tray. It is angled so water flows down the tiles and into the tray. This was how the builders did it.

As you'd need to be kneeling in the tray to do the silicone base that should be weight enough I'd have thought.

Good suggestion though. As I'm about to have a bathroom put in I'll be sure they stand in it to do the finishing

YellowCarBlueCar

I had the same issue above a bath which is used for showering.  The grout fhad failed and the plaster behind was wet.  In my case it had been going for a while and the plaster was crumbling away.  I  used exterior pollifiller to replace the plaster, replaced the tiles, grout, and silicone, and it's been good for at least five years.  The exterior pollifiller is waterproof, has good bonding to the existing surface, and a rough cement-like finish which gives a good key for tile cement.
A layer of exterior pollifiller before the adhesive may do the job

Dave82

Good shout on building it up a bit first with the external filler. Think I might give that a go along with loading the tray with something heavy. I am thinking some paving slabs on a towel might work.

twopenny someone just standing in the tray while doing the finishing won’t work the weight needs so be in there till it all dries in place with a bath you would leave it full with water until everything dry. 

ryan7

As above, it would help if you could weigh the shower tray down whilst a fresh sealant dries.
You could also try this...
https://www.amazon.co.uk/dp/B076FQDS3P/ref=cm_sw_r_cp_apa_fabc_TTRXJEJSERA5V91N7JEH?_encoding=UTF8&psc=1

m0t

It looks from the picture as though the bottom row of tiles are sat on the shower tray. As the tray flexes it causes the grout to crack.

I'm not an expert but when I tiled my bathroom I was told to leave a 2-3mm gap between the bottom of the last tile and the bath and shower. That gap then gets filled with sealant which flexes with the movement and stops your tiles cracking.

Can you replace the tiles with some slightly shorter ones?

Dave82

I have stripped the tiles back off 
Hopefully from these pictures it can be seen that there is enough clearance around the tiles for the shower tray 


I still think the main issue is just the depth of adhesive required to mount the tile to the plaster and keep clearance from the tray. 
Think I will go with the idea of building the plaster up first. Unless anyone can recommend a thick bed adhesive that I can use?

neilmcl

m0t said:

It looks from the picture as though the bottom row of tiles are sat on the shower tray. As the tray flexes it causes the grout to crack.

I'm not an expert but when I tiled my bathroom I was told to leave a 2-3mm gap between the bottom of the last tile and the bath and shower. That gap then gets filled with sealant which flexes with the movement and stops your tiles cracking.

Can you replace the tiles with some slightly shorter ones?

I agree, I don't think there's enough of a gap under the bottom row of tiles to allow for movement.