I have installed cable systems on plywood and covered them with mapai ultra contact before setting the ditra mat. Should I approach the nu heat mat insallation in the same way or can I lay down the mat and the ditra in one go?

Thanks everyone, Sahara.

You will still need to skim coat before the Ditra goes down.

This kind of relates to this topic. I just looked at a job where the installer used Ditra UNDER the heating cables. Obviously this isnt right but is there any harm to the job itself with it being under the cables?

Hi Bill
The whole idea with the isolation membrane (Ditra) is to reduce expansion and contraction directly under the tile. If the cable is between the tile and substrate it defeats the purpose by creating a layer of material which may have movement. The material under the tile will most certainly expand and contract at a more noticable rate because of the temperature changes.
Hope this helps.