Stone Floor Lifting

[Michael Coughlan]

Hi all, I would really appreciate any opinions on the following scenario. Thanks in advance for any help.

House was 20 years old. It had a large hall with carpet on floor (50M2). Carpet was removed and concrete slab was exposed. It was dust free and dry but and reasonably level. Devi underfloor heating cable was installed and a 2 part latex screed poured over it. 2 days later large format marble tiles were installed using ardex flex 5000 white. Tiles were buttered, and fully bedded. 2 and 1/2 years on and several of the tiles are lifting. Hollow sound etc under them. I removed one today very easily using suction cups (after removing any remaining grout). Tile decoupled from adhesive bed easily. Adhesive bed was full ( no voids). The middle of the bed was swollen up in a slight curve which would explain why the tile was rocking on it. I used a kango hammer and removed the adhesive. It was rock hard. 90% of it was still bonded to the levelling compound. However when the compound was removed there was drips of water on the underside and the concrete floor itself was wet.

[Dave]

Hi and welcome.

Are there any central heating pipes within the floor. ?

[Michael Coughlan]

Yes there are central heating pipes in there. And hot water supply pipes I believe.

[Dave]

Are you losing pressure on your heating system( boiler).. i take it , it is a combi system..?

[Michael Coughlan]

It's an older self filling system from a little tank in the attic so not so easy to guage water loss. i could tie up the ball cock I suppose and observe it for a bit. I thought of a heating leak before but there are several tiles lifting in different locations. Even ones in the utility room very far away from the particularly bad ones in the hall.

[Dave]

If you have water under the tiles then you have either a heating pipe leak or water pipe leak or... some form of damp..

You need to determine what is happening.. BUT a leak would not always blow tiles, so IMO i would eliminate these first..

[Dave]

You could run the heating as well and see if the wetting is warm water..?.. hard to tell though as we cannot see what you do.

[Michael Coughlan]

Moisture content under latex screed is only like a dew. Could it be rising damp? Would that lift the tiles off? If the problem was confined to a single area I would agree with the leaking pipe theory but it is too dispersed for that to make sense.

[Ajax123]

20 years old......is there a dpm under the concrete. I think damness explains the failure but you need to explain the dampness before moving forward.

[Dave]

That is my thoughts with what you have said since OP..

If the damp is blowing the SLC, then this will explain the tiles heaving..

What was the substrate primed with before SLC'ng..?

[Michael Coughlan]

I don't know whether there is a dpm installed (I assume there is) and if there is whether it is fully in tact etc. I have studied the areas of the house that are not tiled and there is no obvious dampness apparent. Would a very low level of dampness only become an issue when it's trapped in with the latex and waterproof adhesive?

[Michael Coughlan]

No priming was done before the evostik 2 part latex SLC

[Dave]

The slc and adhesive are water resistant, not water proof, so should allow moisture to rise/escape..through the tile joints but also areas will sweat with rising damp if it is that... hence what you have

It is time to get someone in and get this checked..

[Michael Coughlan]

Get someone in to measure moisture content in the concrete slab to confirm the rising damp theory? Are there other things that could be assessed? Should the entire floor have been "tanked" like they did in all of the bathrooms and "seal the dampness down"? Entire ground floor of the house has over 200 meters of marble

[CJ]

It does sound like rising damp condensing on the underside of the self levelling compound, causing it to de-bond from the screed.

[Daz]

I may be well off the mark here, but Ardex Flex 5000 is not specified as a "stone' adhesive. The adhesive is suitable for UFH and porcelain but it does not state stone.

Just a thought, but full scale water ingress many not be the issue here....

Daz

[doug boardley]

I don't think so Daz, what I'm thinking is OP, (btw, a name would be helpful) has had a screed layed upon a green concrete base and everything has shifted and heaved.

[bobbynz]

marble tiles were installed using ardex flex 5000 white. Tiles were buttered, and fully bedded. 2 and 1/2 years on and several of the tiles are lifting. Hollow sound etc under them. I removed one today very easily using suction cups (after removing any remaining grout). Tile decoupled from adhesive bed easily. Adhesive bed was full ( no voids).
might be a couple of problems including Hydrostatic pressure or rising damp affected the slc. Did the slc come away reasonably clean from the concrete?
the other question should be asked is why did the marble come away easily from the adhesive? The adhesive used here is ideal for damp areas so no problem there but has the moisture finally affected the marble itself. Now that you have this moisture has it and will it continue to affect the marble/adhesive bond? Some marbles do not like moisture at all and thats why the need for special adhesives for marble of which ardex flex 5000 is not.
Like Dave said you need to find out where the moisture is coming from. This can be achieved with the right equipment and expertise.
I would remove a few more of the affected tiles check for moisture and take some photos. Clean and dry the exposed concrete then get a professional in with the correct moisture meter to check the slab for moisture. They might even take up an unaffected tile to check for any pattern in the moisture affected area or perhaps even use thermal imaging equipment to check the extent of the moisture affected slab.
one other question, is there any white powdery substance in the joints and are there any unusual stains appearing through the marble? thats two sorry.
I hate to be the bearer of bad news but when you solve the problem of where the moisture is coming from , it will take some time for the whole slab to dry out if it ever does. If the slc has blown now it may continue to for sometime. This is not just some bathroom floor that you could rip up and fix the problem, so i would strongly advise you to hire an expert in problems like this and can provide you with a comprehensive service. You dont want to go through and have to pay several "experts" when you only need one.
Perhaps one of the guys on TF has some experience with these issues or can recommend someone.
I live just a wee bit too far away to have a look for you as i've done a lot of insurance assessments and find these issues very interesting.
In the meantime as well as the others i'm sure, i will give your problem some more thought.

[garythetiler]

is it stone tiles or slabs,some marble has fibre glass resin on the back this can sometimes cause problem such as you describe

[Michael Coughlan]

Did the slc come away reasonably clean from the concrete? In general Yes but not totally. Bond between the adhesive and slc was fully intact though.

s it stone tiles or slabs,some marble has fibre glass resin on the back this can sometimes cause problem such as you describe . 60 by 60 by 20mm tiles and yes most of them had a plastic type backing with a square mesh design. I thought these are standard on marbles that are prone to breakage.

is there any white powdery substance in the joints and are there any unusual stains appearing through the marble? No, none

(btw, a name would be helpful) Sorry, Michael Coughlan. I just set up my account here recently in a quick mode to view posts. Now that I have posted myself a name would indeed be suitable. To that end I have contacted the admin of the site and they are going to change my user ID.

[Rich]

Hmmm... This is an odd one. Have you contacted the tilers? They might well be able to shed a little more light on what is going on here, even if it is a break down of the materials used and the order in which they did things.

[bobbynz]

It appears that reinforced resin on the back of marble or any stone and tile requires an appropriate adhesive to ensure a good bond to the substrate.
Their does not appear to be any standards for the application of the resin backing so it is the responsibility of the installer to ensure that the correct adhesive is used.
The marble should have been fixed with an adhesive that is not only compatible with the substrate but also with the resin reinforced backing to the back of the marble tiles.
The adhesive required will depend upon what type of material has been attached to the back of the tile.
here is a link for a report on the subject of resin backed marble and stone http://www.laticrete.com/portals/0/tds/tds150.pdf

The problem you face now is twofold. A moisture problem that has reacted with the slc which has caused a dominoe affect by creating a secondary problem with the possible inadequatly adherred marble tiles.
Once you solve the moisture problem, hopefully the secondary problem will resolve itself seeing that the marble has already been down for two and half years.
Has anyone seen this or heard of problems with the resin reinforcement on marble tiles? Apparently the backing is normally used on thin natural stone and marble. Also i know that the extra large format tiles between 3 - 5mm thick have this backing.
Is going to be a problem?
And will the industry require the more expensive adhesives be used to ensure adequate adhesion of the tiles?
What do you know and what are your thoughts on this guys?

[Dave]

User ID changed

[garythetiler]

the resin backing should have been removed from the stone prior to laying them, there have been a few posts on this subject, the resin is used to strengthen the tiles for transit purposes only not many cement based adhesives stick to it and it seperates from the adhesive bed after a while call the stone federation and they will give you very good free advice on the subject 01303 856123