Gap appearing between floor and wall tiles of new bathroom

[J_3926]

Hello,

Our bathroom was installed 9 months ago by what we know were tradespeople who did not have the skill or experience to do so. Several revisits to fix leaks, poor siliconing and retile whole wall and reinstall shower tray were needed and in the end we just accepted it, even though it’s clearly a bad job (and still wasn’t completely leak free).

9 months on and a gap is appearing between the floor and wall tiles. It’s only on one side of the bathroom, which is the external wall of the house. It an old Victorian terrace. They laid plywood on top of original floorboards then tiled on top of this. We also heard a loud bang in shower one day that suggests something has come loose below the shower tray.

Has anyone seen this before, know what is causing it or what they have (I assume) done incorrectly in laying the floor/tiles?

Thank you in advance for any advice.

 

[Timmy D]

Pics? Perhaps the old bathroom had a lon slow leak and has rotted the joist.

 

[J_3926]

Hi, thanks for the reply. We had the ceiling below re plastered and joists visible and the very experienced builders who did that said the joists were fine. Clearly there must be movement and it’s a old property but shouldn’t a professional bathroom fitter prepare the floor accordingly?

 

[Chuck]

A photo showing the gap would be helpful. How wide is the gap and is it changing?

A relatively common problem with Victorian terraces is owners modernise on the cheap by knocking out ground floor chimney breast without replacing the support they provided. Has anything like this been done?

 

[J_3926]

A photo showing the gap would be helpful. How wide is the gap and is it changing?

A relatively common problem with Victorian terraces is owners modernise on the cheap by knocking out ground floor chimney breast without replacing the support they provided. Has anything like this been done?

Not on this side of the house. One of the three chimney breasts has been removed downstairs but on the other side of the house.

Some photos attached.

Gap is around 5mm and growing. First noticed the silicone tearing around Oct/Nov but thought it was just poor silicone. Gap is growing by the week it seems.

I know we’re likely facing ripping the floor up and a probably a total refit. Main things I’m trying to establish are

A) were the tradesmen at fault (their materials and workmanship failed a number of times and I know they only put down 6mm plywood, no other substrate)

B) how can I make sure this doesn’t happen next time around.

If it is the joist then the builders who replastered kitchen and specifically checked the joists while it was open have also failed imo

 

[SimonG]

6mm ply is no good for tiling onto. I would fit 6mm ply if I was putting down lvt or customer wanted cushion floor.

Depending on floor then it would be 6mm hardiebacker or no more ply, glued and screwed. I also like to look under the floor to see if it needs any extra cross bracing.

Needs to come up and be re done correctly.
Preferably by somebody who comes recommended or you've seen previous works.

 

[J_3926]

6mm ply is no good for tiling onto. I would fit 6mm ply if I was putting down lvt or customer wanted cushion floor.

Depending on floor then it would be 6mm hardiebacker or no more ply, glued and screwed. I also like to look under the floor to see if it needs any extra cross bracing.

Needs to come up and be re done correctly.
Preferably by somebody who comes recommended or you've seen previous works.

6mm ply is no good for tiling onto. I would fit 6mm ply if I was putting down lvt or customer wanted cushion floor.

Depending on floor then it would be 6mm hardiebacker or no more ply, glued and screwed. I also like to look under the floor to see if it needs any extra cross bracing.

Needs to come up and be re done correctly.
Preferably by somebody who comes recommended or you've seen previous works.

thanks for the reply. Figured as much but good to have it confirmed.

Fitter that came round yesterday he would also use hardiebacker. Didn’t seem shocked by the 6mm ply so not sure if it’s actually negligence on the original fitters part.

Someone else has also suggested an uncoupling membrane such as Ditra Matt.

 

[SimonG]

Don't need the ditra mat.

 

[Ric2013]

Two layers of ply at right angles was the standard for years. First layer 18mm, 2nd layer used to be 6mm. That said, even if this has been skimped on, it should not result in the floor dropping. More likely is flexing and resultant failure of silicone, not permanent deformation.

Could be seasonal movement of the walls, or due to seaonal humidity: timber reacts to all this. Hopefully not the result of another leak.

A Victorian house: sometimes the build quality is good; in other houses, it is all a bit flimsy and bouncy; in my own Victorian house, I would hesitate to fit a tiled floor at all, as it's a very poor man's cottage and has been chopped about badly an awful lot, and now everything moves all the time. I have come to accept that skirting boards, while somewhat old-fashioned, work well with such a structure; although I am sure more 'technical' solutions are possible; necessary even, if you want a waterproof edge.

 

[J_3926]

Two layers of ply at right angles was the standard for years. First layer 18mm, 2nd layer used to be 6mm. That said, even if this has been skimped on, it should not result in the floor dropping. More likely is flexing and resultant failure of silicone, not permanent deformation.

Could be seasonal movement of the walls, or due to seaonal humidity: timber reacts to all this. Hopefully not the result of another leak.

A Victorian house: sometimes the build quality is good; in other houses, it is all a bit flimsy and bouncy; in my own Victorian house, I would hesitate to fit a tiled floor at all, as it's a very poor man's cottage and has been chopped about badly an awful lot, and now everything moves all the time. I have come to accept that skirting boards, while somewhat old-fashioned, work well with such a structure; although I am sure more 'technical' solutions are possible; necessary even, if you want a waterproof edge.

Thanks. But then I’m assuming the floor wouldn’t be flexing quite so much if the correct amount of plywood or hardiebacker had been used, right?

We certainly won’t be putting tiles down again that’s for sure.

Would such movement not cause this type of gap if vinyl or LVT were used then?