Hi All,

we just bought a house! In the kitchen next to the door we had tiles which were broken and moving, it was really annoying every time you step on them, so we decided to replace them. As the kitchen is done in extension of the house we presumed that the floor underneath is concrete, well... it is, but the concrete finishes about 20cm outside of the door, what follows is rubber like material and there is a hollow space underneath (it could be a waterproof/damp proof membrane) I highlighted this on the picture with the yellow circle nr 1, this material is moving (bumpy) so when you press it you can make a bump in it and than it will jump out. We thought this membrane is supported on wood - so we bought plywood and wanted to screw it in to even out that bit before putting the tiles on - but the screw wouldn't go in (nr 2 on the pic), I think that the tiles broke originally because this is not a solid ground it moves and the movement makes tiles to crack and i'm worried if I will lay the tiles back on it they will crack again, what would be the best way to lay a tile on this surface?

Many thanks in advance for any suggestions.

link to the picture

https://docs.google.com/document/d/1...it?usp=sharing