Cracking grout along tub workaround?

[Mikecclark]

I tiled my sister's shower with subway tile but due to movement in the floor underneath the grout all crumbles were the tile meets the tub.
I spent quite a bit of time trying to brace up the floor and walls and she's had people in there before to Jack up the house and brace everything. At this point I don't see it getting any better and it only seems to be that bottom grout line that cracks so now I'm trying to think of a way to finish it without grout. I can't see Silicon being much better.
Anyone have any ideas? Is there anything I can try mixing with the grout ?

 

[Wayne Brown]

Silicon is the normal method of sealing around a bath

 

[On one]

Might be a bit late for Silicon.....the damage may already be done.

 

[Tony_C]

I'm trying to think of a way to finish it without grout. I can't see Silicon being much better.

One is flexible and the other isn't, of course Silicon would be better

 

[GoneGuy]

Where the bath meets the tile is a movement joint due to the bath flexing when full of water etc. So it will need to filled with Silicon

 

[Mikecclark]

Her house has no basement and wasn't built properly. It was already heaving and sinking and then a tree fell on it and made it 10 times worse. The tubs flexing is an issue but it may also be the floor. I jacked it up and braced it again but it's very difficult to fix and even harder just to get down there.
Are you guys talking about putting in grout and then Silicon over top? It's one of those situations where some spots don't have a 90 degree angle to run a bead of Silicon so I would have to leave some room and try and make a nice level bead.

Any particular kind of Silicon? I assumed it would just last a bit longer then the grout but it's worth a try.

 

[Wayne Brown]

This sounds a bit concerning surely when the tree fell on her property a survey of the damage was carried out by her insurance company ? , was a structural engineers report done ? personally I think the cause of the movement needs to be addressed if not you are only masking the problem I am sorry to say and a permanent fix is not going to be achievable. Kop

 

[Mikecclark]

Ya I think it's about as good as it's going to get now. There's just a bit of movement. Insurance paid her off and she had an engineer come in and brace everything but the bathroom either got worse or was never fixed.
After I got done there was basically just some creaking and some tub movement.
It's been several months and still only that bottom grout line thats cracked.
But that's enough to seriously detract from a renovation.

 

[Wayne Brown]

Well it's a case of raking the cracked grout out removing all the debris before using a quality sanitary Silicon even if there are different gaps and thicknesses that need filling you can still get a satisfactory finish I did some in a hotel recently where they had a similar problem with movement of the baths fill the bath with water whilst carrying out the work and leave it full until fully cured . Cheers kop

 

[moonrigger]

I was taught never to grout the area where the tub meets the wall or where the tub meets the floor. Instead leave a gap there and fill it with Silicon to allow for movement, especially with acrylic tubs, or if tiling on an older substrate that’s gone through expansion & contraction. I like using FlexSeal now. It’s more durable than Silicon, in my opinion.