tiling over concrete and ply - what to use - HELP!

[signalyellow]

Hi everyone
we are looking to lay travertine floor tiles over 2 substrates- a new concrete floor and the existing suspended wood floor ( 18mm ply over the floor joists) because of how the house was built we do not have a straight line where the 2 substrates meet ( along, up a bit, along, up a bit more - am sure you get the picture),.So we would have multiple expansion joints if we went that route
Hardi wallbacker was suggested but can't be laid on concrete according to the spec
So how do we best manage this situation - our tiler is stumped

all suggestions welcome

cheers

Terry

 

[Bubblecraft]

Hi & welcome to TF

 

[White Room]

Hi and welcome....any pics.

 

[Peter]

Not exactly to the letter regarding manufacturers instructions but if it were me I would lay Ditra over everything and use a rubber crumb on the tiles that bridge the substrates. Are there any height differences between the two?

 

[signalyellow]

Thanks for the welcomes. Is pretty level but flexes a little see pics ignore the dark area just fresh screed

 

[signalyellow]

Having issues loading pics from iPad but not a straight line but is on a level just flexes a little at the join. Thanks for the welcomes