To decouple or not to decouple...

[Perfect Tiling]

Hi all...hope you all well. Got a job booked in for next week laying 30 sq mtrs of modular tiles onto a concrete floor with piped UFH. Floor been down for a year and all UFH tested out OK. I feel that it would be best to put down a decoupling membrane but customer not happy with that as he says tiles in his last house were straight onto the concrete and never had a problem in 15 years. Whats your opinions please? Thanks in advance.

[kilty55]

hi,yes id be wanting to lay a membrane

i hate it when these things come up....a customers had a job done with less spec on it and its lasted but in reality sometimes you wonder how they never failed and they think all jobs will be the same

its difficult to make the customer see your point of veiw

are the tiles stone or porc sorry

[nybor62]

in is last house did he have ufh

[Perfect Tiling]

Tiles are porcelain slate effect (cost cutting again) and yes his last house had UFH. I agreed with him that they could go onto the concrete but only on a much smaller floor that would have a lot less expansion. He seems to think that by not sticking straight to the concrete and using a membrane there will be a loss of heat.

[mowzer]

Hi there - I've just posted some pics our our screed on piped UFH in another thread:

Tiling Over Cracked Screed

You could show the customer those - that might convince him. We didnt' know about de-coupling, but wish we did. All screed will crack eventually, and we have hairline fractures in at least 10 tiles in our kitchen (24 foot by 12 foot). Really annoying and in our new extention we have used Ditra and it has been down for 18 months and we have no problems at all. I know it is spendy, but in the end it is a whole lot less hassle.

I suppose you tell them that if they don't want to use a de-coupling product - that they would need to sign something to say that any cracking wouldn't be your responsibility.

[Stewart]

Decoupler all the way and there is no loss of heat using it......

[Perfect Tiling]

Thanks for the advice...will put down the membrane or walk away from the job. Next question...what is the best method to use it as I have never put it down before. Most of my jobs seem to be walls and small floors up to about 6 sq mtrs.

[aphilp]

You want to use Schluter ditra matting fixed with Ardex AF200 using a mosaic trowel

[Daz]

You want to use Schluter ditra matting fixed with Ardex AF200 using a mosaic trowel

My personal preference is for Dural, rather than Schluter. I have never fixed it with AF200 but have been informed of this method many times, however, surely you would use an "A2" trowel as a mosaic trowel will leave too thick an adhesive bed??

[Alan.P]

I've just been back to a job we completed over a year ago, 75 m2 in a basement kitchen diner, nobody informed us about the wet underfloor heating, we had no idea. The result, tiles lifting etc, ufh = de-coupler in my opinion.

[deankyall]

I did 4 houses 18 months ago, straight onto screen with underfloor heating and haven't had a problem at all, I in fact talked to mapei this week and they said de coupling mat wasn't necessary at all, so who's right, I also have started to suggest it to customers,the uptake so far is zero, not helped by my local tile wholesaler who when I sent a customer in to get more info ,told them they could use mapei s2 straight onto green faced chipboard,backed up by mapei, I just want to know who is correct, after all been done for years without de coupling.!!!

[TF Ed]

id go with a de-coupling membrane. its a gamble if you dont with ufh. some will fail, some wont but if it does, then at least you've covered yourself...unfortunately we are living in a blame and claim society now so you have to cover yourself or you could regret it..