To decouple or not decouple - that is my question?

[Daz]

I have an area of 42sqm to tile with 20mm thick limestone (4 colours of varying lengths upto 700mm, with and without fossils).

The substrate is wet UFH which has ben down for 7 years. There are Norfolk quarries stuck on top. That lot is to be covered with slc by a screed / latex specialist.

I told the customer that I would insist on a decoupling membrane as there is too much opportunity for thermal movement IMO and failure with the limestone. The stone supplier has said that there is no need for a decoupler as the UFH has been down for 7 years, so the customer is now questioning my advice .

Is the stone supplier just assuming I am using it as a vapour equalisation barrier, or is there really no need for it?

What would you do, please?

Cheers,

Daz

[whitebeam]

Limestone and decoupling are team made in heaven, thats a yes from me

[Pebbs]

Slow, you are a 100% right, stick to your guns. The amount of times I have had this questioned is numerous, at the end of the day everyone wants peace of mind, and no call backs six months down the line. Who is this dodgy stone supplier saying otherwise?


Lynn

[SandyFloor]

Slow, you are a 100% right, stick to your guns. The amount of times I have had this questioned is numerous, at the end of the day everyone wants peace of mind, and no call backs six months down the line. Who is this dodgy stone supplier saying otherwise?


Lynn

You need to appreciate Slow's predicament here. The customer doesn't know either way and it's Slow's opinion against the supplier which to the customer possibly carries equal weight and the supplier's option is the cheaper.My suggestion is to email the customer the Schluter Youtube link YouTube - Ceramic Tile Installation with Schluter Ditra

This worked for me recently however the concrete was already showing signs of cracking so not too much convincing required.

I think it would be worth pointing out to the customer the implications should the floor fail. I'm also guessing that the cost of decoupling relative to the price of the stone plus the installation isn't that much.

[doug boardley]

deffo a de-coupler Daz, sounds like the stone supplier is trying to keep the customers costs down at no expense to himself. Probably thinking that the extra cost may push the client away from using the limestone.

[Sir Ramic]

Decoupler every time for me.

[Dave]

Think about it.. Smaller tiles like what is already installed... this already produces a layer that moves independently to the substrate and then to add another layer that will again move independently to the quarries and the substrate.. this is really a must here for an uncoupler..

Who is the stone supplier to give advice on substrate issues.. deffo not a tiler..

[Daz]

Question for Admin....

I told the customer that i was going to seek a second opinion on here, but chose to post in the Arms as I wanted the opinion of pro tilers.

Is it possible to move this into a public viewable forum so that I can send the customer the link to prove the point please?

[Dave]

Done......

[Phil Hobson]

Ufh de-coupling every time for me