New member with tiling problem

[rhgnag]

Hi Guys,

Thanks for putting together a great site it has answered many of my technical questions about the proper way to go about things. My reason for posting is I am afraid not because I have any great expertise to offer you but that I have a major problem with the tiling installation in my new bathroom and shower room.

We have been renovating our house for several months. He recommended a tiler who appears to have been very conscientious and careful about his installation. He installed tiles in our downstairs loo, kitchen floor and 1st floor bathroom and shower room. The tiler says he has used the same general approach for all the suspended floors in terms of using a mat and a high quality flexible adhesive.

The kitchen floor seems rock solid even though it is a suspended floor it is on a brand new 25mm ply with new treated joists, and the floor was reinforced so it could take the worksurfaces in the kitchen. The tiler used a ditra mat in the kitchen.

The bathrooms on the first floor which have the problem (on the floor only), on the other hand are on an existing suspended wooden floor, albeit one that was partially braced by the builders. The builders overlaid with 9mm ply as a base for the tiles. I asked them at the time if this was enough, as I have some amateur experience several years ago from our last renovation project before mats were so widely used where we used 12mm ply. I was told that in combination with a mat it would be fine, and they had also fixed any loose board before putting down the ply.

The bathroom floors were laid about 3 months ago, and due to the invasive nature of the renovation we have only been back in for about 6 weeks. A couple of weeks ago I noticed some creaking / crunching in the floor, and this seemed to be spreading. The grout was not visibly cracking and no tiles were lifting, but the floor was moving so figured they would. I then noticed a couple of hairline cracks a few days ago.

I spoke to to the builder about it as I suspected the ply was not fixed or was flexing and convinced him we needed to lift some tiles to see what the problem was. Well when we lifted a couple of tiles the crunching / flexing appears to have been coming from the mat. It appears the mat used in the bathroom which is not Ditra and looks like Genesis G-Matt, but could possibly be something else has separated into two sections. The bottom section is very firmly fixed to the ply to the point that it would be very difficult to remove at all, and the tiles seemed to be well adhered to the top of the mat.

When the installation was done in those rooms, there was no heating in the house, and the room was damp after plastering and adhesive etc. It was also quite cold, but I doubt below 5 Celsius inside.

The general consensus was that the mat had failed. However I am concerned that this is not the whole story. The ply does seem generally well fixed, although there is possibly some very small amount of vertical movement from the area exposed from lifting the tiles. The trouble is I now have a hard time to convince the builder to prepare the floor again, and TBH removing the ply is not going to be pretty. Does anyone know what could have caused this? Could it just be a manufacturing fault on the mat, or is this just a symptom of the real failure? Also what should I do from here rip all the ply out even if it is sound or could be improved by further fixings. This would probably involve tiling over the bottom half of the old mat as it is so firmly adhered.

Any help or advice on this would be very gratefully received.

Rob

 

[nybor62]

the genesis g- matt is the blue one , it does;nt sound like the matt as failed , but part of the matt not adhered properly, 12mm ply is not thick enough
im sure there will be more advice shortly

 

[White Room]

Have you been in touch with the tiler

 

[rhgnag]

Hi Guys,

Thanks for the replies.

I have contacted the tiler who concurs the mat has failed, and has contacted his supplier about it as he is not sure why it has failed. He is worried as he says he has used it on other jobs as well. He is helping us get it rectified, but he is a one man band so has limited resources to rectify the issue. His the supplier has indicated there might be problems with the mat and is coming to inspect as well so we might get some compensation if they agree.

I can just about handle doing this one more time but we need to get it right this time so want to be sure. I am just concerned that the base we have to re-tile may not be good enough and this might have been part of the original problem. I also worry about just overlaying adhesive over the bottom section of the failed mat.

The mat we have looks like the picture here:

Genesis APS International Ltd - G-mat

It is not blue it is a translucent / clear plastic with a felt , fur on one side and a mesh on the other.

The 9mm ply is overlaid on 18mm floorboards, it is not just 9mm or 12mm ply.

Thanks again

Rob

 

[White Room]

9mm ply is to thin anyway, if they come out to inspect the matting they may ask you what thickness of ply has been fixed to the floor boards which may be a get out clause..

It may then be down to who fixed the ply...

Just options to be aware of.

 

[DHTiling]

Hi..

For a mat to delaminate like this then is has been subject to lateral stress... These mats can only cope with a certain amount of stress.

If the ply is cut to tight to the walls this will cause heave , so perimeter joints are required and if the tiles are cut tight, again no perimeter joints then this all adds stress to something that is trying to hold the tiling field in-situ.

If the house was not subjected to any heat till after the tiling then again this is all stress.. so bear this in mind when seeking a cause.

 

[rhgnag]

Hi Dave,

Thanks for the response.

I guess you have seen this situation before. The heating went on pretty quickly due to cold weather, and if the floor had a high moisture content due to the wet trades, could this have caused expansion, and then subsequent contraction as it dried out? The tiler was not happy about the lack of heating at the time.

In the main bathroom a number of tiles are creaking on the longest dimension

Do you think this is more likely than any minor inadequacy in the subfloor spec / fixing preparation?

Is there any way to know for sure?

Rob

 

[DHTiling]

It is a hard to call Rob.. But lateral stress can be quite severe on timber floors that have not been subject to the temps that it will always roughly be at once moved in..

The ply could have swelled slightly from the moisture in the adhesive and as you say wet trades.. Your tiler should have known that the overlay was not sufficient for vertical stress or moisture ingress..

Do you know if a perimeter joints were left at the edges of the installation.?.. insufficient stress relief could be the cause, like i said the decoupler will only cope with so much..

Wait till Genesis have been out and take it from there.

 

[rhgnag]

Hi Dave,

Thanks for the advice again.

We will get it assessed, and let you know how we get on. I will pass on to information the tiler as well so we can check these other options. Hopefully we will get it sorted reasonably painlessly.

Rob

 

[doug boardley]

it sounds like your de-coupler has done it's job but pushed well past the limits, I'm guessing that it's contraction of the plywood that was probably damp. Hope you get it sorted Rob.

 

[Scott]

The builders overlaid with 9mm ply as a base for the tiles. I asked them at the time if this was enough, as I have some amateur experience several years ago from our last renovation project before mats were so widely used where we used 12mm ply. I was told that in combination with a mat it would be fine, and they had also fixed any loose board before putting down the ply.

They were wrong ^^

The ply is way too thin and the decoupler is being used for the wrong type of deflection. I doubt that the temperature change will be the cause as the decoupler should have taken that movement. I havent seen a floor yet that blows because of a temperature change.

Is the adhesive all cracked and is it stuck to the mat or the tiles or bits of both? Got any pics?

 

[Max@ableskills]

Hi. Hope you get this sorted as pain free as possible. Please let us all know how you get on.

 

[rhgnag]

Hi Scottley,

I have a few pictures below where we lifted a couple of tiles in the shower room. The builder was hammering to remove the tile, but the top layer of the mat literally lifted off. You can see the tile mat has separated for some reason anyway. The base of the mat is very firmly fixed to ply. The top is a bit less clear, but still seems pretty solid. It seems like the movement is from the mat separating rather than the adhesive failing, but it could possibly be a bit of both. The grout was only starting to show some hairline cracks, but the floor was moving significantly in places and making a flexing sound like the mat rubbing against itself. The main bathroom which we have left until we can get some more tiles as they are not in stock is over a much larger area (as it is a bigger room I guess).

Rob

 

[DHTiling]

Have you checked to see what the perimeter joint is for floor to wall..?

If this is too tight then lateral stress will cause the tiles to tent up and separate from the fleece.. i did ask this a few posts up..?

 

[rhgnag]

I should also add that the flexing noise stopped once the tiles were removed. There is a very small amount of movement in the ply, (I know it is not thick enough) but it is definitely not making the same amount of noise or movement as it was before the tiles were lifted.

Rob