Cracked leaky grout in shower - replace with silicon?

[Johnking]

I've got hairline cracks opening up between tiles in my shower, and it's leaking enough to show on the paintwork below. This is due to the tiler tiling direct onto marine ply, lesson learned but I'm not in a position to rip it all out and start again.

Can I use silicone to seal more effectively? The grout is Mapei silver grey and I can get identical coloured silicon. My instinct is to rake it out where there are cracks, put silicone in the channel, then grout again on top to make it all look consistent. Will this work, or will the grout fail to bond because of the silicone? In which case, can this be done well with silicone alone?

 

[Paul C.]

sorry to say, sounds like a disaster starting to happen! and if it is, you will only be able to bodge the repairs for so long.

Chances are the ply is swelling. Just because its marine ply, its not fully waterproof. So because it is only water resistant, it will take in water, and if it sits for too long (which in a shower, it will), it will start to blow. Got a few questions:

How long ago was the job done?
Are the tiles Ceramic, Porcelain or Natural Stone, and what size are they?
Was the plywood primed?
Was the shower area tanked and if so what with?
What adhesive was used? Readymixed or Powder? Flexi or no-flexi?
How was the adhesive applied? Notched trowel or Dot'n'Dabbed? If you don't know, you can rake out some grout and see if the adhesive is visble underneath. If it isn't, its been dot'n'dabbed.
How big are the grout joints you need to fill? (not saying there is a solution, but you never know)

 

[Johnking]

Thanks for responding. It sounds like a massive pain in the arse.

It's been done about a year.

Tiles are 600x300mm ceramic, laid in landscape.

I don't think it was primed and it wasn't tanked. I don't know what the adhesive was but I suspect it's been applied D'n'D as the guilty tile can be slightly pushed back.

The joints are narrow, about 3mm. The crack is only around one tile in the bottom row, the upper side not the side next to the tray.

There is zero chance of getting the tiler back. I'm a bit surprised he sounds to have done a bad job as he also laid marble on the floor which has been problem free, and he came well-recommended. The finish is good.

 

[foxhole]

With narrow grout lines there is a good chance the grout has not filled the space, you could re-grout, make sure you use a appropriate grout, standard grout is porous.

 

[Paul C.]

Whoever did that is not a tiler. He needs tracking down and shooting. Then you can take his wallet and reclaim what is rightfully yours; The money you paid him and the compensation he would owe you for doing such a s*** and frankly, dangerous job. When those tiles come down, don't be in the shower. You may lose "Little John" in a split second

Temporary fix..... Silicone or epoxy grout might work for that little bit, but you don't know where else water might be getting in behind it. If none of the other grout is cracked, you could consider putting a sealer over it, which wouldn't be perfect, but would help a little bit.

The trouble is, the water may already be in there, and all you will do is seal it in, which in the long run is causing further damage. People are under an illusion that grout is waterproof and repels all moisture. Wrong. Its water resistance and can withstand intermittent splashing. The Mapei is actually on of the best grouts as it has a repellent built in. But it will only repel splashes

Professional fix will be to rip it all down and start again. At the very least that wall. If the tiles have been that badly fixed and they are dotted and dabbed, you may be able to save them. Replace the ply with a waterproof shower board like Marmox or Wedi. Tank it, tile it (properly.... I promise, you could do a better job than that muppet did), grout it. John and "little John" can shower happily ever after.

 

[Johnking]

Thanks Paul for your warning about safety, it's not a risk I've ever thought of before. I think the tiles will stay in place, even if the adhesive were to fail, which I can see is a real possibility. All of the full size tiles are held to the wall by the edge of the enclosure, and all but the bottom two are also held by the shower controls and the shower-head rail. There are some 1/3 size in the corner, but I'm going to go up the corner with a bead of silicone I think, which should hold them if they came loose, which I think I would notice. That's going to have to do for now, I don't have the time or cash to rip it all out, clean the silicone off everything, fit a backing board, tank, re-tile, grout and seal. Hell, I don't even know how to do some of that! But I will be keeping a careful eye on it and hoping any water in there dries out into the surrounding wall and ceiling below.

I have raked out and re-grouted the dodgy tile, and now it's dried there is no sign of new cracks following a few uses. I'm interested in applying a sealer to help. I don't know how it works though, would I be right in thinking it would not prevent any future hairline grout cracks from letting water through? Can you recommend a brand and application method?

Thanks for your help, it's really appreciated, I will know what to expect in future.

 

[joe-90]

Obviously replacing the whole lot is a big job and big expense. Probably the best bet to repair the grout lines is an acrylic bath/shower sealant. It's tough and flexible and holds the tiles together. It does tend to go mouldy though so get a decent mould resistant one. It's not a perfect cure - but worth a try before you spend big money on a new shower cubicle.