underfloor heating - tile moving dilemma

[gubbins]

Hi everyone

I'm a gutted customer looking for some professional advice on a flooring problem that's developed on my recently renovated / new build property.

I've a number or large rooms (biggest is 11m x 8m) where lafarge was poured over a water fed underfloor heating system. Flexible adhesive (think mapei) was then used to bed 600mm x 600mm porcelain tiles and subsequently litochrom starlite grouting, the work was all completed a few weeks back and looked stunning.

Ive only been in a few days and already there is a some minor tile movement, fissures along the side of the grouting on some other tiles and 'dull or sharp' popping' noises from under a couple of tiles, worse in the high stress areas, which also happens to be where the UFH pipes enter that room. In the one room without underfloor heating ,but everything else the same, there isnt any problem (yet...).

The builder/ project manager reckoned it was must have been due to the tiles being walked on in the stress area before the adhesive had completely set (a lot of trades coming and going) and was prepared to take up and relay that area but now its happening elsewhere that doesn't seem plausible as the only reason. He's not yet aware of the wider problem as i'm only just aware myself but very soon will be, hence why i want to educate myself beforehand.

So whats gone wrong and how do i go about getting it put right which I suspect its going to mean taking up the whole lot and redoing it and the thought of that makes me feel sick. I've not paid any retention fee as yet and have no intention of doing so until this is put right. The heating engineer tested the system before the lafarge went down and put it on again in the period before it was grouted (was cooled ++ before grouting). Only thing that worried this layperson is that with the second test he left it on over a weekend set at minimum on the control / manifold but 27C on the room thermostats then didnt return for about 4 days. Has he weakened the adhesive? What else could it be? Any help is most welcome.

Many thanks

 

[Daz]

Hello & welcome to TF.
I'm sorry to hear of your issues and have a few questions for you....

Did the tiler install a decoupling mat prior to tiling?
Was the UFH properly commissioned prior to tiling?
How soon was the UFH switched on post tiling?
What process was followed when switching on the UFH post tiling?

My biggest concern is that a non-gypsum based adhesive has been used so the floor should have been correctly prepared & primed prior to tiling - this could be the reason for any failure.

Hopefully we will be able to guide you to a satisfactory solution.

Daz

 

[gubbins]

Hi Daz
Thanks for your very speedy response.

Its a bit of a blurr as so much else was going on at the time but..

No, I believe he tiled straight onto the flexible adhesive.

I do know a series of test were run on the UFH prior to tiling. The heating engineer is, im told, very exprienced at building and maintaining UFH systems so ive no reason to believe he didn't carry out the necessary testing procedures at that stage.
I thing it was a min 1-2 weeks before the UFH was switched on post tiling and then i dont recall any post tiling UFH procedure other than the one I mentioned above which was me finding the thermostats set at 27C for at least 4 days (engineer wasnt on site during that period) with the manifold / control set to minimum. All 3 trades have worked a lot together and with these materials / set up in higher end projects so i'm flummoxed as to why this problem should've been allowed to develop.

Thanks again Daz

 

[Time's Ran Out]

You don't mention what type of screed has been poured but no doubt it's a Anhydrite screed (calcium sulphate) and it should have a minimum of 25mm coverage over the pipes. As Anhydrite cures a weak layer of laitance is formed on the surface and is unsuitable to tile onto and slows the drying process. How long after the screed was poured did the tiling get laid? This laitance should be removed up to 6 days after pouring leaving a dense surface to tile onto and help the drying process. If in doubt as to the type/brand of screed use the standard 1mm per day for screeds up to 40mm (over this use 2 days per mm).
You must find out the type/make of adhesive use and the primer/seal applied to the screed prior to tiling.
Are their movement joints in the larger areas? 11m is outside the expected tolerance for floor areas and can cause loss of adhesion, bulging or cracking of tiles.
After the screed had fully dried, the UFH should have been turned on at 5 degree increases to its maximum operating temperature and ran for 3 days. Then turned off and cooled to 15 degrees before any tiling is commenced.
You may find the best answers to your questions from Ajax - the forum screed advisor.
But I expect your own assumption to be correct!

 

[gubbins]

Thanks John, i'm going try to find out the missing information.

One question tho, none of the 3 trades are likely to want to take on any responsibility for the situation whereas it's looking like each one shares some. Just reading some of this forum it became obvious to me that there are lots of different opinions over products and methodology, so are there such things as independent specialists within this field who could be commissioned to look into my problem and produce a report as to what went wrong, and who is at fault, which would carry any weight?

 

[doug boardley]

I agree totally with Daz and John, although my main suspicion is the cement based adhesive onto a gypsum screed that has not been properly primed.

 

[Tabby Cranks]

What I find so frustrating is all the time things like this happen, it damages the image of tiling. When in reality, the excellent advice given above are not trade secrets, all good adhesive manufactureres have this info in their fixing guides, or on their websites.
Check out this link broken link removed
P12 shows you what to do with anhydrite, and P15 for heated screeds.
So sorry this has happended, but if what has heppened is what we all think, then you likely will have to have all done again.

 

[gubbins]

Thanks everyone. Im going to get more information regarding the screed and if any primer was used. I strongly suspect not or i wouldve been charged for that as i was the adhesives as the tiling labour was included as part of the overall project cost. Ditto any matting.

I've just looked at left overs and the adhesive used was mapei keraquick.

Now given none of the three trades are likely to jump through hoops to accept responsibility for such the massive cost of redoing the job (although it's looking like each one may need to share some of the blame) plus just looking through this forum there seems to be so many personal views from experienced tradesmen on best practice and best products, my question is... isn't there some sort of tiling 'governing body' with established codes of practice where i could obtain a specialist opinion which would carry some weight against my tradesmen?

If not, what approach would you guys recommend I take given these three tradesmen work together very often and therefore more likely to maintain a united defence against this layperson? There is a minor works contract in place.

Thanks again

 

[gubbins]

Oh and one more thing..

Do i take it that even in the tiled area without the UFH if he hasnt used any primer or matting I may still develop future problems?

 

[gubbins]

hmmm a couple of my latest posts havent appeared (saying first needs approval) yet the last one has which confuses things. Ill wait to see if the others appear before repeating everything.

 

[Time's Ran Out]

Answer to your post No.7 - Yes.

 

[Ajax123]

Before anyone can really comment properly the missing info is needed. It may well be anhydrite but if lafarge supplied it could be any number of other products as well. As for liability not sure buthetiler wouldprobably shoulder most of the burden unless he has asked the questions he needed to ask of the builder and been given incorrect info. Always a difficult situation to deal with this one.

 

[gubbins]

Thanks ajax and John. we will be meeting over the next day or two so I will get clarification on that and other factors then come back to you experts. At least I now know which important points I need to be pressing them all on to start with, so thankyou everyone who took the time to reply.

 

[Daz]

What area of the country are you in Gubbins? There may be an experienced TF tiler local to you that could provide an initial assessment for you.

Daz

 

[gubbins]

What area of the country are you in Gubbins? There may be an experienced TF tiler local to you that could provide an initial assessment for you.

Daz

Daz, Im not far from Manchester Airport.

 

[Daz]

Wow lucky you! There's loads of top quality guys near you. If it goes slightly "pear shaped" you won't have trouble finding someone from here to assist. Phil Hobson springs to mind but I know there are quite a few established members on here that are more than capable of providing an assessment, if it comes to it.

Daz

 

[gubbins]

Wow lucky you! There's loads of top quality guys near you. If it goes slightly "pear shaped" you won't have trouble finding someone from here to assist. Phil Hobson springs to mind but I know there are quite a few established members on here that are more than capable of providing an assessment, if it comes to it.

Daz

Great! that's very reassuring to know Daz.

 

[gubbins]

Meeting later today so Im looking for further clarification on some points;

If the 'Thermomix UHFL' dial was kept on the minimum setting during the 4 days or so the tiled floor was heated do the thermostic controls on the various zones have any / much effect on the heat that is applied to the UFH? They were up at 27C for the whole 4 days with the thermomix set at minimum.
If as timeless john mentions you should increase the thermostat by 5C steps, is that the thermomix dial or the thermosatic controls on the various zones? How long should each 5C increment be maintained for? And is it then ran at 4 days once at maximum?

Does performing this incorrectly alter the nature of the adhesive and / or anything else?

Thanks again you guys.

gubbins

 

[jay]

might be bed time for me ///but what type of screed is it ,and has the tiler allowed expansion joints especially around the perimeter being a large floor it must have expansion if not this could be the problem

 

[Time's Ran Out]

If I'am allowed to quote - from a major adhesive manufacturers 'bible'.

The heating pipes should be installed according to manufacturers instructions, fixed down and tested prior to being encapsulated in a screed or levelling compound.
If the pipes have been laid in a reinforced sand/cement screed, this must be allowed to dry fully prior to tiling.
A sand/cement screed should be left for 3 weeks with the underfloor heating off, to dry.
After this period the heating system should be turned on and the temperature raised by a maximum of 5degrees/day until the maximum recommended operating temperature is achieved.
This temperature should be maintained for 3 days and then the system turned off and the screed allowed to cool to 15degrees before tiling commences.

If a suitable polymer-modified levelling compound is used to cover the pipes instead of a sand/cement screed, the drying time will be considerably shorter.

Ensure that the cured surface of the floor is rigid, sound, clean, dry and free from any contaminating barrier. Porous or dense substrates must be primed and also impervious surfaces with the relevant manufacturers primers.

Fix the tiles.

Allow to cure. Keep the warming system turned off for at least 5 days to allow the cement to cure. Bring the system up to its operating temperature gradually in stages of 5degrees/day.



I hope this is of help.
You need to obtain the exact type of screed laid and the preparation prior to tiling it received

 

[gubbins]

If I'am allowed to quote - from a major adhesive manufacturers 'bible'.

The heating pipes should be installed according to manufacturers instructions, fixed down and tested prior to being encapsulated in a screed or levelling compound.
If the pipes have been laid in a reinforced sand/cement screed, this must be allowed to dry fully prior to tiling.
A sand/cement screed should be left for 3 weeks with the underfloor heating off, to dry.
After this period the heating system should be turned on and the temperature raised by a maximum of 5degrees/day until the maximum recommended operating temperature is achieved.
This temperature should be maintained for 3 days and then the system turned off and the screed allowed to cool to 15degrees before tiling commences.

If a suitable polymer-modified levelling compound is used to cover the pipes instead of a sand/cement screed, the drying time will be considerably shorter.

Ensure that the cured surface of the floor is rigid, sound, clean, dry and free from any contaminating barrier. Porous or dense substrates must be primed and also impervious surfaces with the relevant manufacturers primers.

Fix the tiles.

Allow to cure. Keep the warming system turned off for at least 5 days to allow the cement to cure. Bring the system up to its operating temperature gradually in stages of 5degrees/day.



I hope this is of help.
You need to obtain the exact type of screed laid and the preparation prior to tiling it received

The screed was lafarge gyvlon : Lafarge Gyvlon Anhydrite based Calcium Sulphate Flowing Screed i'll find out more when we meet in a few days (last one was postponed as one crucial person was held up ) what i'm still needing clarification on is when they are talking about increasing the temperature in 5C increments is that the control (miramix) near to the mainifold that has min- 40-45-50 etc on it or the thermostatic controls dials on on each zone? Like ive mentioned already a couple of times the miramix was set on 'minimum' for 4 days (post tiling but not grouted) but the thermostat dials were put immediately and left on 27C. Was this wrong or does only the miramix setting matter in this case? Is there another section of the forum more suitable for me to post this UFH question as id really like the answer before we meet after the weekend?
Thanks again. Gubbins

 

[gubbins]

might be bed time for me ///but what type of screed is it ,and has the tiler allowed expansion joints especially around the perimeter being a large floor it must have expansion if not this could be the problem

Thanks Jay, im sure i recall seeing the expansion materials around the perimeter as recommended on the lafarge gyvlon downloads; the tiles themselves have expansion joints within a couple of door thresholds separating sizeable rooms. Thanks

 

[jay]

And the sizeable rooms have expansion joints in them separate to the doorway ones

 

[gubbins]

And the sizeable rooms have expansion joints in them separate to the doorway ones

Not visible to me within the tiling Jay. although the same materials, tiler and UFH have been used in rooms of much smaller size/ ie <2m - <3 m in length / breadth and one of those rooms already has a tile that very occasionally makes a very slight sound when walked on.

 

[jay]

It may be a part of the problem and might be worth taking note of ,Lack of expansion joints on a large floor with heating can cause failure . With lack of good prep work and priming. Leaves a lot of room for failure . please keep us updated on this one thanks

jay