UFH and decoupling membrane which way round

[wetdec]

so do you stick the heating mat direct to the top of the ci and then flood with slc so as it fills the cavitys in the ci and then goes over the top of the matt? if you wern't using slc and decided to just tile direct onto the heating mat then wouldn't it be very difficult to force the adhesive threw the heating mat and being able to fill the cavitys in the ci? ensuring the cavitys are full? or would you suggest filling the cavitys in the ci first with tile adhesive allow to dry then heating matt then slc or just tile? I have done it the other way matt slc decoupler then tile and never had any issues. I have always thought that by doing it this way that any expansion caused by the heating matt will not affect the tiles due to the decoupler being between them. But it seems i could be wroung..

We use a pourable adhesive over the cable (just cable not meshed) and bring it flush ready to tile. To fill the voids and leave to dry I supose is a possibility but would draw out your working time.

The heat from an underfloor cable doesnt have the capacity to crack the tiles. An uncoupling membrane used over a heated floor isolates the tiles from the screed movement during expansion and contraction which involves huge tensions and will crack your tiles.

The ci pdf doesnt cover this aspect so what I posted was written as a suppliment to the pdf.

The most importand bond when using an uncoupling membrane is the one to the actual floor the less fiddling in that area the better.

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[wetdec]

Your welcome.........

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[DHTiling]

IMO an Uncoupling membrane works more efficiently over the top and just the tiles on it..

They can be used either way but on top makes the uncoupling work better, as in uncoupled from ALL stress.

Ditra do point this issue out, so i wonder why Dural don't..??

 

[wetdec]

Cant answer that one Dave you better ask them probably involves maths. Would say tho if your cable is under the membrane and the screed tears so does your cable as there is no give there............

By uncoupling you are isolating a problem should it occur the problem originating in this instance at the screed they are designed primarily to counter screed difficulties

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[Dumbo]

just thinking if it was a wetroom wouldnt it be better to lay wp over the whole floor and tray and not underneath?

ted

 

[wetdec]

Ye dead right Neil

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[Dan]

Just bumping some of the older popular (sometimes not so popular) threads. Probably wont be current discussion these days but I just need to do it. So just ignore the thread if it's not current for you.