underfloor heating - tile moving dilemma

[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

 

[gubbins]

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

Oh I have the feeling given the cost of remedying the problem this one is going to run and run so I will do, thanks Jay

 

[Ajax123]

Hi gubbins.

This may be nothing whatever to do with the heating even thouh technically it hould b switched off, there are different schools of thought ref this. One is that the screed shold be unheated. The problem with this is that th screed will naturally expand anc contrct with ambient changes. The counter argument is that if the s creed is heated to a constant temperature of about 20 degrees c during tling this is not only the optimum temp for tile aheives and primers it also holds the screed at a constant temp therefor expansion and contraction is eliminated.

Now then. Question for you....with what was the screed primed and how was this applied

 

[Daz]

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.

What sort of noise is it?
I may be way off track here, but I do have that niggling feeling that a decoupling mat has been used &, unfortunately, failed.

Daz

 

[Time's Ran Out]

I'am of the view it's a dusty surface and they are all loose.
No preparation of an anhydrite screed, UFH left on when tiled and floor adhesive dried too fast.

 

[tommyzooom]

I'm not a plumber, but re the heating controls, In my opinion, the way yours was controlled is the way I would do it, The mixing stat set to minimum, won't allow water higher than (for an example)10 degrees past this point into your floors,
Room stats are little more than an On/Off switch, setting these at 27 degrees will mean that , as the floor/room will probably never reach this temp, they will remain open and "calling" for heat all the time. You could then raise the temp gradually at the mixer stat.

However the heating should remain off during tiling and grouting, and remain off for up to 14 days after completion of grouting,