95sqm onto screed with water based UFH - recommendations?

[Dave]

By expansion, I mean preformed joints within the doorway openings , the room is way too long with out them and you need to eliminate as much stress as possible.
The width is still over the standard length without a joint but uncoupling imo will suffice to give a better aesthetic look.

 

[Wuffles]

Thought I should resurrect this thread in case anyone's interested.

Still living with screed, haven't got round to doing anything yet as other things have got in the way.

Screed will be very much dry by now and we've bought some flagstones for the patio (22mm thick sandstone) which appear to be usable inside too. Took a chance on them as it was only from a picture, but having seen them in the flesh the plan is now to measure up and order enough of those to do the inside too.

Spoke to a man about the decoupling mat and he advised this will affect the performance of the UFH, which I suppose could ring true.

 

[Ajax123]

Don't assume it's dry just dos it's old. It may have had a year to dry but it's also had a year to get wet again.

 

[Wuffles]

Interesting point.

So we should wait longer or do you mean to say it's certainly dry enough to lay flooring on now but not actually totally dry.

 

[Lee@emctiles]

Spoke to a man about the decoupling mat and he advised this will affect the performance of the UFH, which I suppose could ring true.

thats the wrong information you got there. Dural matting is ideal to use as it lets the UFH through. (as does Ditra)

 

[Wuffles]

thats the wrong information you got there. Dural matting is ideal to use as it lets the UFH through. (as does Ditra)

Excellent information, thank you very much. He wasn't a tiler, but an engineer. I'm just trying to arm myself with knowledge.

 

[Ajax123]

Interesting point.

So we should wait longer or do you mean to say it's certainly dry enough to lay flooring on now but not actually totally dry.

Neither. I mean doa moisture test to determine if it is dry before you tile.As for the uncoupling membrane it is true to say, from a purely technical point of view, that every time you add an interface to the floor you reduce the efficiency of the heating system. However the mass of the uncoupling membrane is so low that from a practical perspective it will make negligible difference. It will cost a considerable amount more if the tiles fail due to not using it if using it would have saved that failure from happening. Its not a massive amount to spend in the general scheme.

 

[Wuffles]

I was hoping that wouldn't be required after 9 months of it being down. Is that normal?

 

[Ajax123]

Up to you. Expensive risk to take if its not dry though for the sake of a quick test. A tester costs maybe £30 that would do the job.

 

[Wuffles]

I meant is it normal for screed to not be dry enough after 9 months?

To be honest, it's not my risk, I'm not the one doing it (although it is as it's our floor, but hope you take my point). I would expect a professional to be checking dryness and giving advice if they're taking on the risk.

All I am trying to do is amass enough information to avoid the idiots that do seem to exist as in every industry.