Decoupling mat needed?

[opps]

Hi all

My customer is going to have his hallway floor tiled with small diagonally orientated square porcelain tiles.

The base is floorboards with 6 or 9mm ply over the top.

The tiler started laying them last week end but didn't leave any grout lines so the customer came in on Monday and lifted them back up (and cleaned them).

The client is happy to let the tiler have a second go but I have some concerns- the tiler didn't use SBR etc on the ply. I am wondering if the floor needs a decoupling mat or not.

I appreciate that the response might be to find a new tiler. I have seen other work that he, the tiler, has done and considered it to be OK. The customer, a mate of mine cannot move in until the floor is done.

Here is an image of the layout (not showing grout lines though).



Thanks in advance.

 

[Swwils]

The installation will fail. Get a new tiler.

 

[opps]

Sorry, to clarify, are you saying that a decoupling matt is needed? I have sent the customer a link to this thread. The more info that you can provide, hopefully the fewer problems further down the line.

 

[Swwils]

Overboard with T+G floor panels or at least 12mm WBP ply fixed at 300mm centers.

The ply must be SBRed on the reverse and sides before laying and have an expansion gap thats filled to stop the flexible thinset penetrating. You can then do a few simple tests to see if the prep is suitable.

All tile jobs look good until they fail early, for the sake of a few £'s in basic prep.