Substrates, porcelain,prep - TilersForums.com

[Versatile]

Just looked at a job where they are extending the kitchen to incorporate a garden room
Existing kitchen floor is concrete
New build to be anhydrite
What are the options for prep
I understand the prep for the new screed drying time ect
But would it be wise to de couple
Or could I just put a movement joint where they meet
Tiles are porcelain
Thanks

 

[Stef]

You must put an expansion join where the two meet.
On the gypsum side i wouldn't decouple with porcelain.

 

[J Sid]

no ufh?
treat each area as a separate floor with a movement joint between the two.

 

[Versatile]

Yea new screed had water ufh
I'm doing the kitchen first because of new kitchen being booked in
Then new when dried commissioned ect
Cheers

 

[Versatile]

That should have read will have ufh

 

[J Sid]

Ditra or similar on new screed once dry and ufh commissioned. Plus expansion / movement joint between the two

 

[AndY mac]

Hi steff. Why would you not decouple gypsum for porcelain. Had a job recently where the builders joined the floors but was not a straight join up down left to right. Decoupled then laid 600x600 porcelain. No other solution.

 

[Flintstone]

Why decouple with porcelain ?

 

[Stef]

Hi steff. Why would you not decouple gypsum for porcelain. Had a job recently where the builders joined the floors but was not a straight join up down left to right. Decoupled then laid 600x600 porcelain. No other solution.

You've not got the same shrinkage as you have with a cement screed, I would still break it across doors as these are natural areas where a screed will crack.
For belt & braces then you should use a decoupler but as porcelain tiles are quite robust I wouldn't use it.
You say the builder joined the floors, in that circumstance your trying to use a decoupler for what it isn't really designed for. It really should have an expansion between floors.

 

[AndY mac]

If I used a expansion it would have looked terrible. What else could I have done?