Anhydrite screed with UFH - Help please - TilersForums.com

[creulworld]

Hi,

I am after some advice on my recent project of self build house.

I have recently tiled my kitchen floor which was a anhydrite screed with wet type UFH fitted. The floor has been down for over 12 months or more now and fully dried out.

I have used the following for my floor after seeking advice and using Mapei technical.

10mm Porcelain tiles
Mapei Primer G to prime the floor firstly
Mapei Mapeker adhesive using 10mm half moon trowel applied to the floor only and not to tile back. All tiles were twisted when appling to ensure good bond. This was mixed with water and not Mapei latex plus.
Mapei Grout

The floor has been down for a couple of weeks now and UFH system on.
I have noticed the odd couple of very small cracks in the grout and after tapping tiles near these cracks I can hear that part of the tile is not bonded either to the floor or the adhesive.

I had hoped I had covered all bases with this and the floor looks great. However I fear that the problem could get worse and any advise would be helpful.

 

[DHTiling]

Hello and welcome..

What make of screed is it..?

Did you remove laitence..?

How did you prime.. method..?

Was the heating commissioned first .?

What was the process of turning the UFH on after tiling ..?

 

[Richard Edwards]

Interesting post and welcome to TF

I will await your ans to Dave's Questions and see what transpires

Thanks

 

[Rich]

Im afraid it will only get worse if it is not sorted. Dave has listed all the things we need to know before any advice can be given...

 

[White Room]

Hi and welcome

 

[The Legend; Phil Hobson RIP]

Sounds a bit like thermal shock to me, hope I'm wrong:yikes:

Sorry welcome.

 

[creulworld]

Hi guys thanks for the replies,
Further to Daves questions

What make of screed is it..?

Screed was Lafarge Agilia

Did you remove laitence..?

Not sure exactly what this means guys.

How did you prime.. method..?

Primed floor with Mapei Primer G via brush and left overnight to dry.

Was the heating commissioned first .?

Yes heating had been commissioned for 12 months or so and has been in use ok. Its just that I have got round to Tiling now.

What was the process of turning the UFH on after tiling ..?

UFH was used again approx 2 days after Tiling..

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Just to note also after an inspection tonight I think the Tile has come away possibly from the adhesive rather than the adhesive from the screed.

Also its not all tiles but say 5-10% I am not happy with.

 

[DHTiling]

The laitence is a milky residue left on the surface of the screeds and needs to be sanded off prior to tiling.

And you need more than 1 coat of primer..

When you turned the UFH on , did you do it in stages or just turn it on..?

 

[creulworld]

Any residue has been removed with general traffic in last 12 months, there was none visable.

I gave it 1 coat of primer and then again within a couple of hours.

The UFH was switched on as normal which runs at about 40 to 48 degreesC

 

[DHTiling]

The residue will not just walk off with foot traffic i'm afraid.

So you just turned the heating straight on to required temp..?

You are supposed to turn it on low and then increase in small increments so you do not shock the adhesive and cause a failure.