Regrouting and removal of corner grout

[johncwright82]

I resiliconed the bath/shower a few days ago as I noticed there was some leakage between the bath and the wall at the tap end. I *think* I did a good job of the seal (thanks Fugi kit!).

Checked the seal after leaving it to dry and could still see water ingress under the bath...but not from the bath/wall seal. It's coming down behind the tiles (the tiles are laid on to a boxed out section). Closer inspection revealed this...

IMG_20150331_183501 (Medium).jpg (108.45 KiB) Viewed 1944 times

And here's what I mean by boxed section. Noticed this flexes when you push on it.

The black arrow is pointing to the grout line shown in the previous picture.

IMG_20150331_191012 (Medium).jpg (133.1 KiB) Viewed 1944 times

The horizontal grout has a split running through it. I can only imagine the water is making its way through there. That begs the question about what the state of the adhesive is behind the tile. I am hoping it is not too bad and I can leave it to dry out before regrouting. I've also noticed that the corner joints are all grout whereas I saw on here they should be silicone.

I'm planning on removing the grout around this tile (and other tiles affected by the same problem) and regrouting. Would it be a good idea to remove the grout from all the corners too and replace with silicon or am I making work for myself?

So the plan is...

Remove the grout around the affected tiles.
Leave to dry for as long as possible.
(Possibly remove grout from corners).
Replace grout.
Silicone corners.

Does that sound plausible? Any tips?

[wine~o]

Depends...

If there is plasterboard behind the tiles and has been wet/damp for a while it could well have degraded....


Do you know what addy was used and whether there is plasterboard back there ???

The movement would suggest that it's just the tiles and addy holding everything together......

[johncwright82]

Unfortunately this bathroom was new when I moved in four years ago so I don't know what adhesive was used. I'd say it might have been cracked for, and I'm guessing here, about a year.

I've attached a picture taken from under the bath looking up towards the taps.

IMG_20150330_160531 (Medium).jpg (104.22 KiB) Viewed 1937 times

On the left is plasterboard which is against the wall. Apologies you can't see it here because of the lack of light. Then there's the air gap and then the, I don't know, ply wood? Then there's the piece of wood that the bath sits on (the piece with what looks like silicone/glue on it), and then there's the underside of the tap.

That black layer in the plywood can only mean rot, right?

[Chris Skilbeck]

Depends...
The movement would suggest that it's just the tiles and addy holding everything together......

Hi John C,

I'd agree with Wino here - and if this was my bathroom I wouldn't be happy until I'd removed that boxed-in section completely and re-done it (if the tiles have had water behind them for a while, they may be easier to get off intact than you'd imagine). Any stubborn adhesive can be removed from the backs of the tiles with an abrasive attachment on a multi-tool (buzzy-toy) and a lot of patience and care.

The box, before re-tiling, should be sturdy enough not to move at all. I'd go for a bit of MDF board, at least 16mm thick, on a good firm timber frame, coat the lot with diluted PVA before you re-tile, and yes, do the bottom and the corners with silicone, not grout.

[philprime]

I agree with Chris to a point, I wouldn't be using Mdf if you don't seal it properly it sucks water up like you wouldn't belive.

You would be better using ply or for a better surface I'd use a tile backer board or Aqua board

[Chris Skilbeck]

I agree with Chris to a point, I wouldn't be using Mdf if you don't seal it properly it sucks water up like you wouldn't belive.

You would be better using ply or for a better surface I'd use a tile backer board or Aqua board

Well, I can't argue with that - I'm just a bit behind the times! I've never used purpose-made tile-backer board - is it as easy to cut and fit as MDF?