Two different floor surfaces

[blue-roans]

Hi there everyone,
I'm new to this - not a computer buff. I am seeking advice on tiling my kitchen AND dining room floor which has two different surfaces. Kitchen is concrete, dining room is very close boarded floorboards. I can't use anything really thick because the freezer and fridge have already been built-in by the kitchen fitters so I have very little space underneath them. Is it OK to use ply on both surfaces?
Thanks for any advice.

 

[Aston]

i wouldnt use ply, i would go with a tile backer board over both surfaces on the condition that the floor board area of the floor is structurally strong enough and that there is no defelection in the wooden floor ie the joists AND boards..the tile backer boards are a more stable surface on which to tile and they can be bought in thin sheets too , to save on the height issue..

also, there should (technically) be an uninterupted expansion joint between where the 2 different substrates meet but, it the floor has been down a long time and there is no signs of movement or resent settlement, then you might get away without one but its a hard one to call accurately call without seeing the job...

theres only so far you can go with the advice on a forum without seeing the job.