Decoupling Mats AND Expansion Joints on Tiled Floor

[Arrenite]

Hi Folks,

 

I am tiling on a 75mm screed with underfloor heating from an ASHP. I have large windows in my kitchen / sitting / diner (high solar gain). My tiler is going to use a decoupling mat, and tells me that he has never had a problem when using decoupling mats, and that expansion joints are not required. 
 

Do you think expansion joints are needed as well as decoupling mats? Or is that overkill?
 

thanks

 

 

Arenite
 

 

[Russell griffiths]

There’s a big difference between expansion joint and a movement joint. 
what sort of area are you talking about, I have probably 50-60 m in one area with no expansion joints, but I do have 3-4 movement joints where the large area joins thin smaller areas. 
I was always told that was the place cracks would occur. 
imagine the shape of a tennis racket, it will always crack where the head joins the handle. 
I also have movement joints in every doorway. 

[Arrenite]

Russell,

 

the biggest room is 11 metres long, by 6 metres wide. 

[Temp]

Watch out at doors between rooms. Should have movement/expansion joints there. Each area of screed can shrink towards it's own centre cracking where the meet. Has happened to us.