Issue with Granfix Flexible Fastset - Tile Advice

[Old School]

Hi,

This is my first post! Just a question to see if anyone has any experience using Granfix?

I have used Granfix Flexible Fastset for a job in which the tile shop supplied this adhesive. I have never used this adhesive before but the bag was labelled as fast set suitable for underfloor heating, wood, porcelain and waterproof.

The customer layer 18mm of marine ply and then laid Wediboard. He then fixed the underfloor heating and I came into screed the floor with the Granfix. I then tiled the floor the day after. When I tile I always apply my adhesive to the whole tile and then fix to floor.

However, one month later the customer explains to me the tiles are lifting off the floor. When I go to see what has happened I see the tiles have lifted and once the tile is removed it is clean, as if no adhesive has been applied. All the adhesive has large cracks in it.

The underfloor heating was put on 3 weeks after the job was complete. So I can't see this being the explanation.

Has anyone experienced this problem with this adhesive?

I have never seen this before and always use the same method that I have used in the past 26 years with my preferred adhesive, and think it is strange this happens on an adhesive I have never used before.

Thanks

 

[White Room]

Not an adhesive I use nowadays but never had any problems with it, did the customer turn the ufh up gradually....

 

[Old School]

The job was complete in February and the customer messaged me in May to say the tiles felt loose and grout was coming away. I did notice the under floor heating was on 19 degrees!

I think you may be right in thinking they didn't turn it up gradually and stuck it on full wack.

I have never seen this before!

Perhaps the customer was trying to use the underfloor heating to heat the whole house!

thanks!

 

[AliGage]

Can't say I've ever used it before either. But would ask the same question as whitebeam.
Customer wasn't tempted to turn it on beforehand or crank it right up after 3 weeks did they?

 

[AliGage]

Also what tiles were they?

 

[Old School]

The tiles were 300 x 600 porcelain.

I can't say if the customer did do that as they didn't say anything to me, but the tiles were quite warm to touch and the house was really warm.

 

[Brian the Tile]

Hi Old School i use granfix adhesives all the time and never had problems ,thats not my way of fixing tiles (one at a time) but i cant see that being the problem,i would take a guess at the underfloor heating being put on to soon and not gradually,the problem you have now is are they going to tell you that they did everything as they should have,and to be honest ill bet they couldnt wait to put it on full blast when you had gone ,but im sure they wont tell you that,good luck and as i say i have used granfix for a long time now without problems i find it good to use

 

[Ceramico tiling]

Yes I have had issues with Granfix. It doesn't work with porcelain tiles.

 

[thompsonbrown]

If its the granfix in green bags I only use it on walls. I often use granfix ultimate on floors and always back butter the tiles.

 

[The Legend; Phil Hobson RIP]

Sounds like thermal shock to me.:sofahide:

 

[Rookery]

Sounds like thermal shock to me.:sofahide:

Me too. Does the cracking in the adhesive follow the run of the cable?

 

[SJPurdy]

I'd go back to the shop and ask them to get the granfix rep to come out and look at it. If they won't help then contact granfix direct and ask them. I would think that they will be able to tell from a sample of the failed adhesive what the likely cause of failure was -although will they admit it if they've forgot to add the flex bit to the mix!

 

[m3fitter]

you say the client fixed the ply and wedi board, was it screwed down properly, was the wedi board adhered down, and with what.. sounds like could be a prep problem ???? rather than an ufh problem

 

[AliGage]

My guess would be thermal shock. If you spread the adhesive direct to the back of your tile and there is none on the tiles now that have popped. To me that screams thermal shock.
As rookery said. Do the cracks follow the cable runs? Might be worth a call to the tech support of the UFH Manufacturers. Ask the question that if their technicians came out for an inspection would they be able to high light thermal shock from that inspection.

 

[Brian the Tile]

whatever is the case i dont think you can blame the adhesive just because you dont like it or prefer not to use it