Hole in floor where wall was - now what?!?!?

[SteveyJ]

HI All

Dont know if this should be posted here but I dont know what to put it under so if it needs to be moved mods please do.

I'm tiling my open plan kitchen dinner, and I have had a window cut out and fitted a large pair of french doors. Now I want to tile all the floor but I have a big long whole the length of the doors where it now reveals the cavity which the old internal skin used to be infront which the window sat on (hope this makes sense)?

So how do I tile over this hole and tile upto the doors sill;

My thoughts are fill the whole with balast (but then this is touching the ground and also external wall below DPC so will damp then potentially enter?
Or board the whole floor with cement boards and hope it straddles the weight across a 3" hole (sounds bodgy lol)

What should I do?

Thanks Steve

 

[White Room]

I would use a bitumen paint/tanking and then use a sharp sand screed to fill the hole.....

 

[micko]

Use a cavity closer and then screed over.