Tiling Anhydrite screed with wet UFH

[Blunt Tool]

This thread and others prove that there is still not a definitive code of practice regarding materials and installation onto this screeds and seems to be getting more and more confusing the more it is debated. I’ve only done a couple of them around 50 metres each and BAL came and spec”d everything and installed to the letter as he told me to. Never heard back 2 years and 3 years later so that’s good enough for me and would stick to what I know.

 

[Ajax123]

This thread and others prove that there is still not a definitive code of practice regarding materials and installation onto this screeds and seems to be getting more and more confusing the more it is debated. I’ve only done a couple of them around 50 metres each and BAL came and spec”d everything and installed to the letter as he told me to. Never heard back 2 years and 3 years later so that’s good enough for me and would stick to what I know.

My comments are nothing to do with the screed. They would be the same regardless of screed type.

 

[Ajax123]

Thanks again to everybody for their input. I'm glad my post has prompted a debate which I've found really helpful in understanding the issues.

I am hugely relieved that a decoupling layer is not required - this was going to cause me the greatest headache of all and even more costs. I am perfectly relaxed about putting in extra hard or soft expansion joints and realise now that it doesn't matter that these aren't structural joints carried through the screed. The plan is to go for two, dividing the floor into 3 x 5x5m bays, as Ajax suggested.

I am inclined to stick to 3mm grout lines for aesthetic reasons and because the tiles are rectified (10mm thick). I had a long and very helpful chat with a technical guy at Tilemaster who was happy with this provided sufficient expansion joints were provided. I might incorporate additional soft joints if I start having sleepless nights worrying about this.

Ajax, I wonder in the failure case you mentioned whether expansion joints had been provided? and who picked up the tab for the remedial work. I'm guessing it would have been a big number.

In a similar vein, I wonder whether any supplier of materials would provide a watertight guarantee provided they were happy with the specification. Of course, if the job really did go belly up, the first port of call would be the tiler who did the work but I suspect that wouldn't get me very far. In my experience, the customer always end up paying when things go wrong since it's always deemed to be his fault!



Thanks again to one and all

Cheers, Jonathan

It was several 10s of thousands of pounds. No movement joints were incorporated into the floor which was about 8mx15 from memory. The builder picked up the initial tab through insurance. He I would think then chased the timer but ultimately its the disruption to the client that was the worst. Always difficult to see things go wrong when someone sinks their heart soul and life saviings into a project.

Suppliers wont guarantee workmanship or design unless they are directly involved. My company is a supplier. We can guarantee out material and that it will perform in the way we say if it is used in the way we recommend. We provide a huge wealth of information to back up what we claim and so that people can do it right. Sadly there are so many people who "know better"...

 

[Richard Head]

Thanks Ajax and everyone else that has contributed.

I think we have nailed where the risk actually lies in this sort of job.

I'm going to have a go at laying a couple of tiles myself to see how I get on. I have just bought the materials and a shiny new notch trowel so what can possibly go wrong?!

Fortunately I am not under any time pressure and can afford to lose a few tiles if it all goes wrong and I have to rip them up.

Of course the definitive test will come when the whole floor has been laid and grouted in and its been through a few heat cycles but I'm hoping any problems will manifest themselves before then.

I have a great deal of respect for the many here who are making a living out of doing this work, doubtless under huge time and cost pressures. Hats off to them - I know I couldn't do it.

Cheers, Jonathan

 

[Flintstone]

Laying a few tiles isn’t gonna be the problem, is it dick? It’s when the whole floor is laid without the correct methods that the problems start

 

[Dumbo]

Laying a few tiles isn’t gonna be the problem, is it dick? It’s when the whole floor is laid without the correct methods that the problems start

I am so naive and gullible his user name has only just clicked

 

[Skipp3r]

In my experience, once the 'milk' (latience) was removed with a circular grinder, it was a good to then prime floor with acrylic Weber primer with two coats in a crossways fashion ( first coat up n down second coat left n right) then ditra. This has been our remedy on multi million pound houses.