Mapei ultracolour plus is it supposed to be flexible? Disaster strikes :(

[Notts]

Firstly hello all, just joined the forum as I've had a disaster and am hoping someone can help.

I've tried googling this and searching the forum but I can't find much (maybe I'm doing it wrong?) so here goes.

About 6 months ago I tiled my sisters bathroom using large real stone (I think) tiles. The bathroom is upstairs and on a wooden floor, so she got a reputable guy to do sort the floor with plywood before I layed the tiles.

I went to the local tile wholesaler showed them an example of the tiles to be layed and explained the situation (upstairs, ply floor etc etc). For which they gave me adhesive and Mapei ultracolour plus grout.

Anyway everything was fine until after about 2 months of the tiles being layed when the grout started breaking up I was away and by the time I returned 6 months had passed and the grout in all the areas that are walked on the most is breaking up really badly.

The floor does have a very slight spring to it if you bounce your weight up and down but this is only visible to someone standing a few feet away and watching you bounce up and down (to the person bouncing it feels very solid).

Also I've removed a few chunks of the grout and it is hard and brittle and does not appear flexible at all? Nor does it say anywhere on the bag "flexible" just ultracolour plus/bioblock/drop effect etc etc.

Can anyone advise what the problem is likely to be? Is it the grout or something completely different?

Regards

David

[grumpygrouter]

The issue is the bounce in the floor. This should have been rectified before installing the tiles. Your grout is a highly modified flexible grout but it will not flex sufficiently to allow that sort of movement. Also the stone tiles will be very heavy adding extra loading to the floor. No easy fix I am afraid, sorry.

[Sir Ramic]

The substrate is the problem. If you have deflection then you need to sort that out 1st. You say the floor was plyed before you tiled but with what thickness and method.

[Notts]

Hi, huge thanks for the quick replies.

With regards to the floor question:

First he laid stips of wood on top of the old floor at 14" centres then put 12mm ply on top and then put in what seemed like about a million screws. I'd not thought to question it at all as he came recommended because he's done the same for several of my sisters friends over the years, as well as a lot of other joinery work.

[Sir Ramic]

But deflection is deflection and the most of the time the 1st thing to give will be the grout.

[Sir Ramic]

What stone have you used ? What adhesives did you use and what other preparations did you make ?
How large an area of room are we talking about ?
Its very unlike Mapei grout to exhibit the symptoms that you describe.
Was an expansion joint left around the perimeter of the room ?

So many questions due to being so many possibilities , we need to know the full story.

12mm ply is not BS should have been min 15mm to be technically correct.

[Notts]

What stone have you used ?

My mistake, Slate effect porcelin around 13" square and about 10mm thick.

Getting old, memory ain't what it used to be, what day is it again etc etc

What adhesives did you use and what other preparations did you make ??

PCI Timberflex 2 part.

Floor clean, free of dust.

How large an area of room are we talking about ?

Approximately 3m square

Was an expansion joint left around the perimeter of the room?

Yes.

12mm ply is not BS should have been min 15mm to be technically correct.

Is that likely to cause problems? Will have a look in her shed as there are quite a few scrap bits that I can measure to make sure.

Hope that helps, and thanks again for the help.

[Notts]

Got her to measure the scrap bits and yes it's 12mm.

[Sir Ramic]

The deflection will be the cause. As you said Stone I was wondering why the stone hadn't cracked 1st. Now yo say porcelain it all makes sense. Deffo deflection issues IMO.

[whitebeam]

You say that wood strips were put down then the ply laid on top, was there a gap between the ply and the floorboards due to the strips being laid..

[Notts]

Right well that clears that up looks like the floor's got to come up and be completely re-done.

Thanks for pointing me in the right direction.

"You say that wood strips were put down then the ply laid on top, was there a gap between the ply and the floorboards due to the strips being laid."

Yes, the wood strips were fitted at 14" intervals, screwed on top of the floorbords and the ply fixed on top. This was to level the floor.

It did all feel very solid when it was finished but it definately flexes now, whether it's the wood he fitted or the floor underneath I have no idea.

Could the added weight of the tiles have caused the floor to bow/bend/flex?

[Sean fsy]

Surely there will be air pockets in between the floor and ply, can't fix an uneven floor with strips. If the pipes are under any part of the floor it will be expanding and contracting the air pockets.

[Notts]

Well it's all arranged. Monday I will start taking the tiles up, once they're out it's replace the entire floor and start over.

Will be searching for a different joiner, and armed with this info I'll be able to say exactly how I want it done using much thicker ply.

Thanks to everone who has helped.

David

[RichieRich]

Sorry to hear about the problem mate. Yes at least 15mm ply and I would personally use a decoupling membrane on top of the ply to be extra safe. 2 part flexible adhesive and flexible grout. That should do the trick. Good luck.

[Notts]

Update incase anyone's interested. Revisited the job yesterday and as soon as I lifted 1 tile the problem was blatant.

Just pressing my foot lightly on the floor underneath causes it to creak and bend visibly. If I put my weight on it (I'm not a big heavy guy either) bends severely by at least 3 or 4 mm whilst the surrounding tiles remain rigid and level.

So I called the guy who layed the ply on top of the floor who says:

"There's no way it's a problem with my floor mate. If it was, you would have had problems as soon as the grout/adhesive had set, not 2 months later. It must be a problem with the original floor underneath."

There are no cracks in the ceiling below so I'm not convinced it's a problem with the joists.

Has he got a point with the 2 months thing?

[peteablard]

Just pressing my foot lightly on the floor underneath causes it to creak and bend visibly. If I put my weight on it (I'm not a big heavy guy either) bends severely by at least 3 or 4 mm whilst the surrounding tiles remain rigid and level.

There's your answer! As someone stated earlier 12mm isn't up to the job, 15mm minimum should be used and if possible i'd use 18mm. Depending on how much movement there is and how heavy the foot traffic is it can take a while for the grout to start cracking. IMO it's definately the guys fault for not prepping it correctly.

[GirlRacerRed]

David, did the ply guy advise you/your sister how he was going to prep the floor? or did he take instruction from you/your sister?

this is a crucial point. if you/your sister told him how you wanted it prepped i.e. 12mm ply etc, then you have no come back on him because he was doing what he was instructed and paid to do. however, if the ply guy told you that 12mm ply was suitable preparation because you told him in exact detail what you would be doing with the floor afterwards, then I think 2 months down the road and he needs to come back and sort out his prep work.

but remember, if your ply guy isn't a tiler, how will he know that British Standards for ply floors should be 15mm minimum?

[jay]

Deflection in the substrate is your problem you need to sort the substrate out first i would call the chippie back