cracks in new travertine floor: advice needed!

[KateME13]

Thanks so much -- I'm amazed how much help we're getting from this forum. I now have the missing information that I hope will help with the diagnosis. To recap:

* the new joists are 6” x 2” C16 grade joists spanning 274cm (the width of the kitchen) spaced at ~30cm centre to centre. (Part of the floor is supported on original joists that are 4” x 2” supported at half span.)
* There is 80 mm Kingspan insulation between the joists supported by battens on top of which are laid 15mm poly pipes for the underfloor heating. The heating was tested at full heat when the chipboard was down but before the tiles were laid. It has not been tested since.
* On top of the joists is laid 600 x 2400 x 22mm engineering grade tongue and groove chipboard, screwed to the joists. This is laid in a brick pattern.
* On top of this are 6mm sheets of 900 x 1500 Hardibacker board (I presume this is the stuff). These were laid with min 1mm gaps between the boards (up to 2-3 mm) in a brick pattern, with the gaps filled with flexible sealant. They were screwed at 200mm centres (but not glued) to the chipboard.
* The surface is modular filled and honed Travertine from Topps tiles (see link)
* This is stuck with 'dotted and dabbed' Mapei Kerabond adhesive (this is white - I did them a disservice in an earlier post by saying I thought it was brown).
* Liquid ‘Fire and Earth’ sandstone grout was then allowed to run between and under the tiles to take up any void under the tiles.
* The tiles were then sealed.

The problem: there are several cracks in the tiles, each running across several tiles and all, as far as we can tell, running along the joints between the Hardibacker boards (or linking them). There are about 14m of cracks in all and they have lengthened progressively over a period of a few weeks since the floor was laid. The kitchen units have been fitted, so taking up the whole floor would be a substantial job.

I think this is pretty much all the information that is available. Does this help to confirm or change the diagnosis? What should we do? The builder is as puzzled as we are but has been very good so far about saying that he will fix the problem but obviously we want to understand the cause so that we can ensure that when he does it won't happen again.

Thanks so much for any help you can give.

 

[Gazzer]

* this is stuck with 'dotted and dabbed' mapei kerabond adhesive (this is white - i did them a disservice in an earlier post by saying i thought it was brown).

bingo !!!!!!

 

[DHTiling]

Sorry to say this but not only a bad fixing method but that adhesive is not suitable for timber floors with or without isolastic admixture.

It is suitable for UFH on solid substrates but deffo not timber.. this is fixer installation error.

 

[White Room]

The hardie board should have been laid onto a single part flexible adhesive before they were screwed..

The dot and dab is a major issue and the flowing grout is'nt good either...you will have more cracking later because of the fixing issue..time to consult your tiler.

 

[KateME13]

Hi--

But can you explain why the cracks follow such long lines if the d&d'ing is to blame for the problem?

Thanks again for the supportive and constructive posts on this.

K

 

[DHTiling]

Info is stated here>>> http://www.mapei.it/public/COM/products/78_kerabond t_gb.pdf


click back in previous page.. Wrong adhesive also used.. not suitable.

 

[hillhead]

Not acceptable this 'dot and dabbing' method of fixing now a days.
Oceans of space beneath your tiles, even the grout would not fill that.
Tap your tiles to see how many hollow areas you find, take your pillow too probably.
The builder should not have done this, sorry to hear all this yet again.

 

[KateME13]

Hi--

As some of you can tell, I've only just worked out how to thank you all for your replies...) Any suggestions you may have about moving forward on this (bearing in mind the kitchen has been installed...) gratefully received...

 

[Gazzer]

Sorry only one way Its gotta come up and start again.

 

[One Day]

Hi--

But can you explain why the cracks follow such long lines if the d&d'ing is to blame for the problem?

Thanks again for the supportive and constructive posts on this.

K

I expect it to be because the dot and dab method combined with the wrong adhesive, all makes for a weak bond.
Any movement along the lines will easily transfer through to the travertine.
Travertine, depending on quality and thickness, doesn't really have a great "pull" (shear?) strength, unlike stone such as granite, so it will happily (or sadly) crack along the movement lines.
The fixing method was very wrong - contrary to BS.
The adhesive choice was wrong.
The grouting method was wrong. "flooded to take up voids" sounds like excuses to me! There should be ZERO voids beneath your stone in any case.
You would easily win your case with this.
Bad job, start to finish and 100% unsalvageable I'm sorry to say.

 

[White Room]

Do you have any pics of the full kitchen concerned

 

[DavieA]

I cant beleive what ive been reading with regards to this floor from start to finish, Ive only been tiling 4 years and not done alot of natural work and am always learning from this site but id also say its a must for UFH and a natural tile to use a decoupler membrane and also correct adhesive and fixing mehod is a good start to. I regularly use keraflex only becase of its thick bed properties as in it can go upto 15mm thick and long pot life meaning im under no pressure.

Dont know if anyone would agree but maybe plying the floor over chipboard for additional strength (provent bounce) may have helped and then applying the membrane ontop of that (for lateral movement)therefore doing away with the cementboard as it provides no strengh properties and is only ther to gce a good tiling surface but you already will have an excellent surface to fix to with the decoupler and by fixing using a full bed method and ensuring 100% coverage, possibly even backbuttering tiles.

 

[One Day]

id also say its a must for UFH and a natural tile to use a decoupler membrane

I believe it's recommended now by the British Stone Federation to be used in all instances, but the jury is still out on it being a necessity.
Certainly, if budget allows - it can't do any harm!

 

[jwatson]

sorry to read about your problem with the instalation. i have read every post in this very interesting read and every tiling profesional on here will give you the same advice; that it is a rip up and start again. before going back into battle, read back through this post and arm yourself with all the correct info.

To get the result that you want, a pro is needed for this job. stone is specialist work. someone on here will live close too you and would be happy to help. check credentials.

hope you get this sorted


"dot and dab" is a bread and butter NO NO to any TILER.
A de-coupling membrane will give so much piece of mind.
Use correct adhesive.

Next time get a tiler to do the tiling. there is a part of the forum that you can post jobs and pros of here are always happy for the work in these testing times

 

[Rich]

I will never understand why these builders are always so confused that their master pieces have fallen to pieces, did he say "Iv done this loads of times and never had a problem"?

Unfortunately the guys are right above, this is a rip out and start again job but this is ALL down to your builder, he should be paying for this not you. The installation was wrong from start to finish

• The cement boards MUST be bedded down into a solid bed of adhesive before being screwed down, this fills any voids under the boards, I would expect any floor that has been put down onto cement boards without glue to fail.
• The Wrong adhesive was used therefore it will not hold regardless of anything else. I would expect any floor that was laid with an unsuitable adhesive to fail.
• The tiles were laid on blobs of adhesive, this is wrong wrong wrong. This leaves yet more voids under the tiles and every adhesive has a max depth, I would expect any floor that has been laid dot &dab to fail.
• I have not come across a grout that would be suitable for this. All grout and adhesive has a max depth/joint width. Grout is not designed to take the weight of a tiled floor, you need a solid bed of adhesive not grout. I would expect any floor laid in this way to fail.

It is so upsetting when we get threads like this (and we get soooo many). It seems to me that this is all down to the builder and he should be taking the kitchen out, ripping up the tiles, floor and cement boards. Then he should be paying for a tiler to redo the work correctly. This is down to you but I wouldn't want him doing it all over again, he clearly has not idea what he is doing.

 

[Rich]

I cant beleive what ive been reading with regards to this floor from start to finish, Ive only been tiling 4 years and not done alot of natural work and am always learning from this site but id also say its a must for UFH and a natural tile to use a decoupler membrane and also correct adhesive and fixing mehod is a good start to. I regularly use keraflex only becase of its thick bed properties as in it can go upto 15mm thick and long pot life meaning im under no pressure.

Dont know if anyone would agree but maybe plying the floor over chipboard for additional strength (provent bounce) may have helped and then applying the membrane ontop of that (for lateral movement)therefore doing away with the cementboard as it provides no strengh properties and is only ther to gce a good tiling surface but you already will have an excellent surface to fix to with the decoupler and by fixing using a full bed method and ensuring 100% coverage, possibly even backbuttering tiles.

I would agree that a decoupler would have been a very good idea but the problem with using a membrane over ply or chipboard is that adhesive really doesnt bond well to these, a cement board is mechanically fixed. In an ideal world a cement board and then a decoupling membrane would be belt and braces but its getting people to pay for it. With regards to the fixing method, you have just raised another point. Trav MUST be back buttered and the voids in the back of the tiles filled with adhesive, I back butter all floor tiles to ensure a good coverage.

Dont think it is worth asking if the builder back filled/buttered the tiles.

 

[bugs183]

I know its going over old ground but it appears that there are two major problems here, the floor is flexing thus causing the straight line cracks, and the method of dot and dab as everyone says is a total no no, and even more so on travertine.
It was never going to work, if the builder becomes troublesome, just call the adhesive manufacturer in, they'll condem it and give you a full spec to fix the new floor with. Everyone has pice of mind then.
Sorry but does look like the kitchen and the floor needs to come up. If the builder plys and retiles from the feet of the kitchen this won't help either as any stress or flexing from under the units could still upset the whole floor, 14m of cracks is alot of movement, something is moving.

 

[KateME13]

Hi all--

First of all--thanks so much to everyone who has contributed to this thread--we really appreciate the advice which has been given. I have been back through the posts, and would like to sum up the advice as to where we go from here. I have highlighted areas where I'm note sure of myself--grateful for any comments--this is what we'll go back to the builder with.

1. The whole floor will need to come up, down to the chipboard.
2. On top of the chipboard--should we lay backer board AND decoupler, or just decoupler? I understand that if we do use backer board, it needs gluing AND screwing to the joists. DavieA suggested doing away with backer board, and replacing with ply (what thickness?), then decoupler. If we did that, I presume the ply should also be glued and screwed. What's best?
3. On top of the decoupler--travertine tiles need 'back-buttering' with the right adhesive--keraflex was mentioned (again by DavieA--thanks very much), and definitely no dotting and dabbing to be used. Adhesive must be pale coloured or it will seep through and look as though the floor has measles.:smilewinkgrin:
4. Grout--any special tips here?
5. Clean and seal the tiles.
6. 2 weeks after the tiles have been laid, the UFH needs testing at 5 degree intervals up to maximum heat.
7. Cross fingers.:lol:

Thanks again for your help so far.

 

[Rich]

Hi Kate, a decoupling membrane and backer boards is belt and braces but not many people will pay for both as it will add a lot of money to the job. I really do not believe that it was a lack of a decoupling membrane that has caused the floor to fail, a combination of not gluing the cement boards down and the dot and dab adhesive is much more likely. If the chipboard was correctly screwed down so there was no deflection, then the cement boards fitted correctly and the tiles fixed with a solid bed of adhesive, I think that the floor would still be intact. This would be my advice, rip the floor up back to the chipboard and carry out each stage as above.

 

[KateME13]

Dear everyone who has contributed/been reading this thread--
I wanted to follow up all your advice etc. with an update: our builder has agreed to pull up the whole floor (including taking out the units), pay for new tiles, and contribute towards the cost of a tiler to redo the floor. He will then put the units back, at no cost to us. So we are really happy with this, and wanted to thank this forum for the advice and support which allowed us to take a constructive approach to dealing with this problem. Now--all we need is a good tiler who knows about water u.floor heating and travertine tiles! Thanks again, everyone.

 

[Del W]

Got your pm Kate.Will be in touch.

 

[Bathfix Bob]

I'm glad he did the right thing and hopefuly learnt by his very expensive mistake.

 

[Del W]

Looked at this floor tonight.A nice couple with a problem that can be sorted.They are so glad of the info/support provided on here. Well done TF.

 

[Ken Bruty]

Great to see a happy ending

 

[kilty55]

minted result