Large Floor - Advice on Expansion Joints needed - Tile Advice

[Whooshman]

Hello All,
I’m looking for some advice regarding expansion joints as I am planning a large floor around 110 sqm- I have attached the layout.
The tiles will be Porcelain, 600 x 600
The sub floor will be 18mm ply in all areas except in the dining room (dining room is the 26sqm area on diagram) and conservatory which are concrete screed.
My thoughts were to put Expansion Joints in the following areas:

1. At the toilet door
2. Between the main hall and the walkway
3. At the door to the utility room
4. Between the walkway and the dining room
5. Between the walkway and the conservatory

How does this seem to you? Would I need extra in the dining/conservatory areas? Any help/advice would be greatly appreciated.
WM
(Background: I have around 8 years experience but have never tiled a floor the size I’m asking about)

 

[J Sid]

Are you really tiling straight on to 18mm ply with no uncoupling membrane?
What is under the ply?
Is there any deflection on the floor?

 

[Whooshman]

Sorry, missed that out, I've recommended he uses Ditra matting.

 

[White Room]

Sorry, missed that out, I've recommended he uses Ditra matting, not sure what you mean by deflection though?

Bounce on the floor...

 

[Whooshman]

Bounce on the floor...

thanks....tried to edit that comment when I realised what it meant

 

[m3fitter]

insist on ditra.. not recommend.. as you guarantee the install. you'll need decoupling across the different substrates and then you've raised it all by 6mm in that area, so insist on ditra'ing the lot, it makes sense... and good practice, remember to prime the wood, and use correct adhesive on ditra and tiles

 

[Whooshman]

insist on ditra.. not recommend.. as you guarantee the install.

willdo, walked away from a job a couple of months ago - 33 sqm, customer refused decoupling or expansion.

 

[White Room]

Read the adhesive manufacturers instruction on priming...

 

[m3fitter]

willdo, walked away from a job a couple of months ago - 33 sqm, customer refused decoupling or expansion.

quite right, if we all do it, in the end, they will all know, that's it the right way to do it, for instance, look at the amount of cracked tiles / grout that float about on rated people and checkatrade leads.. I've seen tiles crack on UFH screed personally after 5 years ( 600x600 porcs )

 

[Whooshman]

where does this leave me with expansion joints though? Would de-coupling on its own be enough? I didn't think so, hence the original query

 

[White Room]

Are the walls stud work or block work....

 

[Whooshman]

Are the walls stud work or block work....

mostly stud

 

[White Room]

The only real stresses your'll get are from the block walls, the stud work will be fixed to the floor anyway....

 

[Andy Tiler]

Looks ok to me whooshman,you should be fine with that!
is the 18mm ply straight onto the joists?

 

[Andy Tiler]

My choice would be to overboard the ply with a cement backerboard glued and screwed!!